Rules Enquiries: Q&A


This page provides a list of questions received by the Formula SAE-Australasia Rules Committee, along with the corresponding answer.


 

Question

 

Answer

DUAL FUEL INJECTION 
Since there is no mention of dual stage injection in the rules, we were wondering if it is allowed to use engines with such capabilities. For example, our selected engine is Honda CBR 600 2009 which uses a dual stage injection system and in addition to the 4 injectors that inject the fuel into the cylinder head, another 4 inject fuel into the intake manifold.
In response to your recent enquiry regarding Fuel Injection Systems, Dual Stage, or dual injector location, systems are permitted.  If the system is wholly a Low Pressure System it must meet all of the requirements of Clause IC1.91 or, if High Pressure or Direct Injection, the requirements of Clause IC1.9.2.    If the system is a hybrid of Low and High Pressure, then all requirements of both clauses must be met.

RE01-2018  Thursday 17 August 2017
FUEL LINE CLAMPING
Attached is a picture of the OEM fuel rail on which our fuel lines are to be clamped, we were wondering whether or not this fuel rail fuel entry satisfies the condition of being barbed or not. Furthermore, are the clamps whose picture is attached in the enquiry satisfies the three conditions of required clamps per this rule or not.



With respect to your recent query relating to acceptable fittings and clamps for fuel lines, the spigot with the exterior circular beads qualify as satisfying the barbed or bulb requirement, provided the tube is clamped between the two raised beads.A wire clamp would definitely cut into a hose and therefore the double wire clamp you show is unacceptable.A flat band clamp with rolled edges is what is expected. Examples are shown on the USA FSAE website Frequently Asked Questions.

RE02-2018  Friday 8 September 2017
GRADE 8.8 BOLT REQUIREMENTS
Does an OE combination satisfy the conditions listed in rule number T11.1.1. The stud is not 8.8 grade bolt and we have difficulty understanding the extend of the mentioned rule to whether or not the bolts used to attach the wheels to the hub must be 8.8 grade. Furthermore, does the fact that they are flat head contradicts with rule number T11.1.2 or not?

The Fastener requirements in clause section T11.1 relate to the Metric Class and head type for nuts and bolts used to retain clevises, hubs, uprights, wishbones etc. They do not apply to the pressed in wheel studs and where OE wheel studs/lug nuts would be satisfactory.  The example shown would appear to be more than adequate for a Formula type vehicle.

RE03-2018  Monday 11 September 2017
Li BATTERIES FUSING IN IC CARS
In regards to the regulations on the use of Batteries based on Lithium Chemistry & specifically the Discharge current cut off switch: I have been unable to locate a battery on the market with a built in cut out for high discharge. The battery we are proposing to use has high and low voltage protection. Is the voltage cut off enough to satisfy safety concerns or is a Fuse in the line is required. The battery proposed (SSB Power Sport LH7B-4-GK) is rated to 150A discharge and has a cut of 8.2 Volts.

In response to your query regarding the protection for Lithium batteries in the rules, a fuse or other overcurrent protection is required.  The low voltage cut- off does not satisfy the requirement for which the overcurrent protection is intended and is to protect not just for thermal runaway but more to protect the wiring/personnel.  Lithium Ion batteries of all chemistries have a significantly higher short circuit current than lead acid, and are likely to be in the range of thousands of amps.

ACCUMULATOR HOLES PROTECTION
Ducts are being added to our accumulator for cooling. They are made of non-conductive material and are in contact with the cells and accumulator walls, however the smallest duct (shown) is 60mm from cell to wall. There is no opportunity for anyone to contact the Tractive Path of the system. Does the current design meet the intent of the rules?








The intention of rule EV4.5.1 is to prevent accidental contact of fingers or tools to live parts of the accumulator, either with the car assembled, or during maintenance. You should also consider the insulation on the battery pack itself. If you are able to demonstrate that the insulation on the battery pack itself is adequate for the full tractive system voltage, and a probe cannot be inserted from the exterior to contact the cells or internal HV items, then your design should be compliant. You should be able to check this for yourselves with a sample probe.  If either the insulation on the cells is not suitable for your full pack voltage, or contact can be made with the probe, you should consider adding additional insulation or an  additional means of preventing the insertion of the test probe.

RE07-2018  Monday 26 February 2018
ELECTRIC MOTORS LOCATION & PROTECTION
The team wished to apply the Wheel Mounted motor exemption for a motor mounted in an exposed position outside the main frame.







The intent of this rule EV 4.2.3 was to allow wheel embedded motors without the obvious incompatibility with frame protection. Apart from ensuring adequate electrical disconnection protection for your motor, the mounting must also fully comply with EV4.2.2 with surrounding tubular structure per T3.4.  It appears that your motor is mounted in a position subject to this rule but no surrounding structure is shown, as will be required.

RE08-2018  Thursday 5 April 2018
GROUND PROTECTION FOR WIRING & FUEL LINES
Given that the triangulated lower face of our monocoque, will not impact the ground under any circumstances. Will routing brake lines and LV wiring through this area satisfy rule T7.1.7?


The intention of rule T7.1.7 is to protect the electrical and brake hardware on the vehicle from impacts, both from the ground and from foreign bodies. As the exposed equipment will still be susceptible to damage from foreign bodies, the proposal is not acceptable.

RE09-2018  Monday 26 February 2018
HV CONNECTOR CLAMPING
On our cell stack PCB, we are using a Radlok connector. This connector is fastened to the PCB by an M6 cone lock nut, one of the material layers of the PCB is an FR-4 standard fire retardant composite material. Given the strength of this material is this considered to be compressible and therefore not meet rule EV4.5.8?



PCBs being made of fiberglass are considered to be compressible and so are not allowed to be included in a bolted high current path connection. This is because once compressed, the resin can gradually flow, causing a relaxation of the joint. Note also, nyloc nuts are not suitable for securing high current connections, as the nylon has a relatively low softening temperature, making them ineffective when the joints get hot.

RE10-2018  Monday 26 February 2018
ACCUMULATOR MOUNTING DESIGN
The mounting point makes use of an 8mm Metric Grade 8.8 stud to fasten the accumulator to the car. Due to the inherently unserviceable nature of studs, the use of a slot in plate has been conceptualised. The plate must be located with other fasteners to both react the torque of the stud and to locate the plate longitudinally during the fastening of the accompanying M8 nut.The smaller fasteners serve only for locating and torque reacting purposes. They are not intended to carry any impact load.  Does the use of smaller-than M8 fasteners to locate this bracket contravene EV3.4.8 c ii?
The proposed arrangement as shown in your component drawing appears not to be acceptable as a replacement for the required M8 mounting bolts. Per Clause 3.4.8 c The mounting must “Be able to withstand 20kN in any direction” and thus are intended to secure the battery box in 3 dimensions against forces generated during an impact or possible rollover event. As presented, the pins indicated in your design would provide adequate restraint in 1 or 2 dimensions only so are not an adequate replacement for the required bolts.

RE12-2018  Monday 12 March 2018
ACCUMULATOR COOLING LIQUIDS
For accumulator cooling is silicone oil permitted given it is defined as an oil?  We’re attempting to implement an active cooling system for our accumulator and require a dielectric heat transfer material with a viscosity similar to water. This is the safest material we have found to meet our needs.














By the Safety Data Sheet, the material is classified flammability level 2 “moderate”. Despite the rules requirements that the battery pack be operated at or below 60 degrees C, there will be insufficient margin between the operating temperature and the flash point of the fluid. There are likely to be localized hot spots within the pack, so it is possible that flammable gasses could accumulate in the air spaces within your battery pack. Due to the high energy content of the battery pack, it will not be possible to demonstrate that ignition sources are not present within the battery, so the fluid must be assumed to be unsafe for this purpose. As there are currently no rules specifically governing cooling fluids for battery packs, the rules committee suggests the following for guidance:
- The fluid should be non-flammable, or at least self-extinguishing
- The fluid should be stable at any temperatures up to at least 90 degrees C to prevent localized boiling or off gassing
- The fluid should not be listed as dangerous goods

RE14-2018  Sunday 1 April 2018
BENT TUBE SUPPORT
Per T3.5.5; If the bent tube in question is the upper side impact member, is this it required to have a support tube of the same diameter and thickness (1.375’’ x 0.047’’) as stated in the rule above or is this already accounted for in the increased diameter of the tube?




If your Upper Side Impact tube is bent, then it must have at least one tube of the same diameter and thickness running from where the furthest deviation due to the bend is located back to a node on the chassis.  If of the correct dimensions, a tube running from the centre of your USI tube back to the node at either the base of the Main Roll Hoop or Front Roll Hoop would meet this requirement.

RE19-2018  Friday 6 April 2018
EV OVERCURRENT PROTECTION - 1/3 RULE
We would like to ask clarification for the first item in rule EV6.1.5. Specifically, requiring a “three time lower” requirement on the external overcurrent protection device? If we put 7 cylindrical cells (where each cell has 2 fusible links, rated at 22.5A each) in parallel and form a battery block. Then we connect 110 of these cell blocks in series to form the accumulator pack. The sum of parallel fusible links rate will be 22.5 * 2 * 7 = 315A, does this mean we have to connect in series an external fuse with a rating lower than 105A?







You are correct in your assumption that a fuse rated at 105 Amps or less will be required to protect the battery pack in that configuration. The 3x rule (EV6.1.5.1) is an attempt to make sure that 2 scenarios don’t happen; A: If a single fusible link blows there is time for the AMS to detect it and shutdown the vehicle and we don’t have a chain reaction where as soon as one link blows the rest blow because the remaining set of fuses has an overall smaller ampacity) and B: If the entire pack is subject to an over-current the main pack fuse which is rated for full TS voltage blows before the parallel cell fuses which are not voltage rated. Given the different shapes of the time current curves, the 3x factor was adopted as a reasonable way to have a simple requirement for the teams to follow but make sure we keep adequate spacing at all points on the time current curve between the main pack fuse and the cell fuses.

RE22-2018  Friday 6 April 2018
SHUTDOWN BUTTON ELECTRIC SYMBOL
Can you provide us a close picture of the button or model name of the button mentioned in EV5.3.4? I was unable to find the button with a red spark on a white-edged blue triangle.

You appear to have misunderstood the rule. It does not require the Shut Down Button to carry the symbol but it be clearly located adjacent to the button.  You could draw and produce your own symbol or they can be located on line.

RE23-2018  Friday 6 April 2018
HEADREST PADDING DIMENSIONS
Rule T5.6.2.  Does this rule require the energy absorbing foam to be a minimum of 1.5 inches thick or is the rule only requiring the assembled thickness of the restraint to be a minimum of 1.5 inches thick?

The foam padding must be a minimum thickness of 38 mm.   If the dimension were applied to the total head restraint, inadequate thicknesses of foam could result.

RE25-2018   Friday 13 April 2018
FRONT RADII ON WING SECTIONS
Rule T9.5 & T9.5.1. 1. Does this rule assume the front radius of aerodynamic devices in a ‘normally operating’ configuration i.e. the running configuration of the vehicle?  2. How will front radii be measured given the radius of an aerofoil is constantly changing?  3. Will the secondary flap of a front wing and by extension any other forward facing aerodynamic device be measured?
All forward facing edges are potentially contactable by a pedestrian so must comply unless protected by a grille or some other guarding.  The radius could be measured in any operating position so if devices are adjustable, your design must ensure compliance throughout the range of movement.

RE26-2018  Friday 13 April 2018
SES QUERY
T3.19/T3.32
The UTSS (N)” in the FBH Support Structure fails SES. The guidance notes within the SES gives an alternate method to prove the equivalence provided that the value is >33%. Do we need to provide equivalent calculations for: 1. ONLY “UTS (N)” because that is the only criteria we fail, or  2. All the three properties “Moment of Inertia”, “Buckling Modulus”, “UTS (N)”






In response to your request regarding the completion of the SES (T3.29 T3.32) we wanted to verify the response with our SES reviewers. In providing equivalent calculations, you should provide all of the calculations as per the following;

  • Show area of monocoque skins, A
  • Calculate Moment of Inertia of skins, I, derived from the cross-section of the skins to the chassis center line, comparing to derivation of baseline tubes.
  • Show EI is greater than three baseline tubes
  • Multiply A by UTS value from panel testing to prove equivalent strength
RE27-2018  Wednesday 9 May 2018
FIRST YEAR VEHICLE DEFINITION
A6.8.  First Year Vehicles: In the 2017 competition, a car was run with a chassis that was mostly aluminium honey comb monocoque with a steel space frame rear section. For the 2018 competition, if the front monocoque section is significantly redesigned but we reuse the rear section with minor modifications of brackets, suspension mounts and engine mounts, will the vehicle be classified as a first-year car?
Provided the front monocoque is significantly different, plus there are some modifications to the rear structure and not a carryover rear suspension, the vehicle will be accepted as 1st Year Car.  You may not gain the maximum points in Design because of the lack of new design approach to the rear structure. 

RE29-2018  Thursday 19 April 2018
WHAT IS "BRAKING HARD"
EV5.6 Brake System Plausibility Device (BSPD). 1.Can you please give a clearer definition of “braking hard”? Is there a certain pressure value at which we consider as braking hard? 2. Regarding the following section: “The action of opening the AIRs must occur if the implausibility is persistent for more than 0.5 sec.” Does it mean we need to open the AIR within 0.5sec after the BSPD fault is detected?











The pressure required to be considered ‘braking hard’ needs to be determined by the team as it is dependent on the design of the braking system. It should be close to the point of locking the wheels. At technical scrutineering the scrutineer will select one of your drivers (usually the smallest) and ask them to demonstrate that they are strong enough to active the protection system. As such, you should seek to strike a balance between too high a braking force that the drivers cannot active the system in an actual emergency and too low where it causes nuisance trips. The action of opening the AIRs must occur if the implausibility is persistent for more than 0.5 sec.” should be taken to mean that the driver panics and depresses the brake pedal hard, the AIR must trip. It is allowable for you to have a timer which checks for a consistent brake press for up to 0.5 seconds before tripping to reduce nuisance trips.

RE30-2018  Friday 27 April 2018
EV; SUPPLY OF POWER FROM TSMS
Rule EV4.11.2 requires any pre-charge circuitry must be supplied directly from the TSMS. 1. Can AIR be supplied by 12V voltage line before the TSMS? 


It is a requirement that the actual current flowing through the AIRs passes through the TSMS, such that when the TSMS key is removed the current path to the AIRs is physically broken. As such the arrangement suggested is not acceptable.

RE31-2018  Friday 27 April 2018
LV FAN INSTALLED IN ACCUMULATOR
Rules EV 4.1.4 & EV 4.1.5:    We are designing a cooling system in the accumulator container which involves fan in the accumulator. We would like to clarify if fans are allowed in the accumulator container if they are powered by the LV battery but galvanically isolated.


LV equipment within the battery container should be avoided wherever possible. If an LV system must be installed within the battery compartment it must be galvanically isolated from the chassis and be physically protected from the tractive system by either an insulating barrier or the defined air gap.

RE33-2018  Thursday 3 May 2018
MONOCOQUE MAIN ROLL HOOP MOUNTING
Regarding Rule T3.34.2  Given the rule states the hoop must be attached at the top, and the bottom, and at an intermediate location: are three attachment points required on each side to attach a main hoop to a monocoque chassis, as shown in the following diagram?





Your interpretation of the rule T3.4.2 is a correct interpretation of the intent of the rule. A tube frame structure would usually have three welded mounts; one at the top of the body structure; another at the Upper Side Impact Tube; and one at the bottom of the  body structure.The drawing you included showing mounts at the top, bottom and adjacent to the height of the USI tube would be in full compliance. This rule will be clarified in the 2019 US FSAE Rules and/or 2019 Local Addendum.

RE34-2018  Friday 27 April 2018
SES QUERY; EV 3.4.6 ALT MAT'L EQUIVALENCY
SES. EV 3.4.6 Alt Material - Shear. Given the inherent advantage of being able to tailor the mechanical properties of a composite materials to suit an application, does the required “proof of equivalency” dictate the entire alternative material panel must meet the same shear strength as the steel baseline or is there scope to meet shear equivalency only in regions where such shear strength is required?


With regard to your question regarding equivalence of a composite material accumulator container to steel and if the equivalence requirement applied to the complete panel surface, we advise that it must be equivalent to 0.09/1.25 mm thick steel over the whole panel surface area, not just at load bearing points.  Steel also provides localised impact/penetration protection for the Li batteries over the whole panel surface, therefore the composite must be equivalent to the nominated thickness steel over the full area

RE35-2018  Thursday 10 May 2018
FASTENER EDGE DISTANCE 
Regarding Rule T11.1.3  Does the second bolt hole on the same bracket (and therefore the chassis) count as a free edge?



The edge distance is intended to be the distance from any bolt hole within the mounting plate/reinforcement to a neighbouring free edge of the monocoque. The distance to an additional bolt hole within the mounting plate/reinforcement itself may be less than this dimension.

RE32-2018  Thursday 3 May 2018
SES Query: EV3.4.6 Alt Matl – Shear 
Alternate Frame Accumulator Container Perimeter Shear Test

Given the inherent advantage of being able to tailor the mechanical properties of a composite materials to suit an application, does the required “proof of equivalency” dictate the entire alternative material panel must meet the same shear strength as the steel baseline or is there scope to meet shear equivalency only in regions where such shear strength is required?

Similar to how monocoque structures only need to show equivalent shear strength within the front bulkhead support and side impact structures, and how hard points are expected where necessary to distribute loads through the panel.

With regard to equivalence of a composite material accumulator container to steel and if the equivalence requirement applied to the complete panel surface, we advise that it must be equivalent to 0.09/1.25 mm thick steel over the whole panel surface area, not just at load bearing points.

Steel also provides localised impact/penetration protection for the Li batteries over the whole panel surface, therefore the composite must be equivalent to the nominated thickness steel over the full area.

RE35-2018  Thursday 10 May 2018

Electronic Throttle Control 
What is the meaning of “Notice of Intent to use deadline” on Electronic Throttle Control (ETC)? We are confused with the deadline for ETC on 14 Sept for IC vehicles.

 



The Notice of Intent is a specific form available on the US FSAE website and is as required per the rules. This is all clearly spelled out in Clauses IC1.11 through IC1.18 and their related sub-clauses. It must be agreed to by the officials in advance for you to be allowed to use an ETC. The September 14 date is for the submission of the FMEA. Very few teams attempt to use ETC and we would recommend that any new team not attempt to adopt ETC in their early years.

RE37-2018  Thursday 3 May 2018

Head Restraint Width 

Rule Reference T5.6.2 c.  Does the total head restraint width have to be greater than 15cm or can the head restraint at one point be less than this?



The width of the head restraint must be a minimum of 150 cm over the complete restraint if an adjustable restraint, or over the full minimum height of 28 cm for a fixed restraint. A fixed restraint of greater than 28 cm height could have the width reduced outside the 28 cm height.

RE36-2018  Thursday 3 May 2018
BMS Outside the Accumulator
We want to confirm if it is allowed to have the BMS outside the accumulator container. We are using a 132 cells model Orion BMS 2. It is equipped with 2.5kV isolation for every 36 cells and 100V isolation for every 12 cells.


It is the intention of the rules that when the AIRs are open, no tractive system voltage should be present outside of the accumulator enclosure. The proposed arrangement will not be acceptable as there will be live conductors at tractive system voltages outside of the battery enclosure when the AIRs are open

RE38-2018  Friday 11 May 2018
Wires in Accumulator Container
Rules Reference EV4.5.11 and EV3.3.8
Is orange GLV system wire allowed in the accumulator container?


In response to your recent question on GLV wiring colour, Per EV 4.5.1, even inside the accumulator container, orange wiring may not be used for GLV wiring which is not part of the tractive system.

RE39-2018  Friday 11 May 2018
Disconnection of BMS before Maintenance Plugs
Rules Reference EV3.3.3.2 and EV8.1.2
We are advised by our BMS manufacturer, Orion that we must disconnect the BMS voltage tap sensing connector on the BMS side before the maintenance plugs are disconnected. Otherwise, the BMS will be damaged. Our BMS will be packaged inside the accumulator container.We’d like to clarify that for maintenance of the accumulator and whenever accumulator segments are removed from the container, is it allowed to disconnect the BMS side voltage sensing connector before disconnecting the maintenance plugs
.








V

3.3.3

.

2

In response to your enquiry regarding the disconnection of your BMS before the maintenance plugs and the Clause EV3.3.3.2. The rules committee cannot provide specific design advice to teams for their vehicles. The requirements of the rules takes precedence over manufacturers recommendations and you are required to develop a solution that is in compliance with the rules. Many teams have successfully used Orion BMS systems previously without encountering this issue. You should consult with Orion and consider the Orion documentation carefully in selecting the location of maintenance disconnects within your battery pack.You may disconnect the Orion unit before disconnecting the maintenance plugs in order to achieve isolation however you should carefully consider what voltage potential the person completing the disconnection may be exposed to, and what damage may be sustained to the unit as the plugs are connected or disconnected. We would expect you to have a documented safe work method statement for any such task.

RE40-2018  Friday 11 May 2018
Rubber Hose Connecting Fuel Tank to Filler Neck
Rules Reference IC1.8 and IC2.6
Provided all rules pertaining to the Fuel system (IC section 2), particularly IC2.6 and IC1.8 are met, I would like to confirm if using fuel grade rubber hosing as an intermediate connector between the fuel tank and the filler neck would be acceptable.Note that the filler neck is solid and its position would comply with IC2.6, furthermore it will be securely mounted to the vehicle chassis and will not solely rely on the rubber hose for mounting.There appears to be no mention excluding this practice, (except for an implied diagram in Figure 14, page 96 of the rules)and I am aware it is used in commercial road worthy vehicles
In regard to your query regarding the use of appropriately rated rubber hosing as an intermediate connector between the Filler Neck and the Fuel Tank, this approach is acceptable provided that all requirements of Clauses IC1.8 and IC2.6 are met for all components and it is not positioned where it may suffer contact damage.

RE41-2018  Tuesday 5 June 2018





Motor Shield
Rules Reference EV2.1.3
Does the scatter shield surrounding the motor have to cover the side, front and back? Or just around the side of the motor.











In regards to your question on guarding for the rotating motor body per EV2.1.3 , we advise that the shielding must cover the motor circumferentially to protect for disintegration or rejection of parts and it should extend around 40mm beyond the motor at each end to provide for parts being ejected at some angle to the perpendicular. You do not show the motor mounts, nor other protection around the motor, so we cannot be more definitive but as it is mounted exterior to the main structure of the vehicle, it must of course also comply with Clause EV4.2.2. At Technical Inspection the overall installation will be checked for sound practice as to ensuring overall protection from accidental contact with the motor by personnel as well as major impact.

RE42-2018  Tuesday 5 June 2018

Monocoque Main Hoop –Definition of “Bottomof the Monocoque”
Rules Reference T3.34.1 and T3.34.2
T3.34.2 states that the main hoop must be mechanically attached at the “bottom of the monocoque”. The lowest possible attachment location on the monocoque, to avoid edge loadingand attachment bolts intersecting the monocoque floor, is located above the underside of the monocoque. T3.34.1 states that the main hoop must extend to the “bottom of the monocoque”.Given both referenced rules use identical wording, does T3.34.1 treat the lower main hoop attachment point, defined in T3.34.2 as the “bottom of the monocoque”, as “the bottom of the monocoque”? Does the roll hoop need to extend past the lower edge of the attachment location?











In regards to your questions on the definition of the bottom of the monocoque for the purposes of the Main Roll Hoop mounting, and application of the related Clauses T3.341 and T3.34.2, we advise as follows: The intent of the rules is to achieve as close as possible a correlation with a tubular vehicle structure, where the bottom of the Main Hoop will sit on top of the bottom side impact frame rail. It is appreciated that the need for mechanical fixing of the lower MRH attachment to the monocoque will result in this mounting being slightly above the top of the monocoque floor. Provided that it is mounted as low as reasonably possible and of sound engineering design, then this will be generally acceptable. Your indicated 44 mm above the bottom of the monocoque floor is satisfactory. (The cut end of the MRH will usually be 25mm above the bottom of the vehicle in a tubular structure).

If the MRH were mounted on the inside of the monocoque we would expect the bottom to sit right on top of the monocoque floor. For an externally mounted MRH, extending the MRH bottom below the bottom of the lower attachment provides no extra support, so terminating it level with the bottom of the lower attachment (at 44 mm above the bottom of the monocoque tub) is acceptable.

RE43-2018  Tuesday 5 June 2018

EV Additional Soldering on High Current Path
Rules Reference EV3.3.7
The rule specified soldering can’t be used to connect single cells. We’d like to ask, in addition to crimping/fastening, are we allowed to add additional soldering on high current path?


Soldering in the high current path is not permitted for FSAE vehicles, even when the joint has other mechanical fastening methods. Solder is a poor conductor of electricity and forms a resistive joint that under high currents can lead to excessive heating and failure of the joint.

RE45-2018  Wednesday 6 June 2018
Monitoring of Precharge and Discharge resistors
Rules Reference Addendum EV5.1 and Addendum EV5.1 (2017)
The rule states that components within the pre-charge and discharge circuits that dissipate heat must be monitored for thermal overload by PDOC, which includes power resistors. Although, the rule does not state that all components within the pre-charge and discharge circuits must be monitored by PDOC. Our Precharge and Discharge resistors are specified to continuously handle the current that they will experience. As seen in Table 2-7 and Table 2-9, continuous power rating of our resistorsis 100 Watts, whereas even at 500V the power dissipation is25Watts giving a safety factor of approximately 4.Temperature rise at 25Watts is approximately 25°C and the power resistors can handle the maximum spot temperature of 200°C.The power resistors arecompatible with 2017 rules. Our discharge resistor was under continuous load for a number of endurance runs with no issues in 2017and 2018. With these specifications, dothe power resistorsstill need to be monitored by PDOC for thermal overload?

This is a commonly asked question. While the Rules Committee cannot provide specific design advice for your vehicle, however, some general guidance is clearly needed on this point. If you elect to follow option 1 of addendum EV5.1 (2017), you will be required to demonstrate not only that the resistor itself is rated for continuous power dissipation, but also that it is appropriately installed such that the heat will be conducted away from the resistor and that the heat dissipated from the resistor will not pose a hazard to the batteries or other equipment around it. Installing the resistor in a small box with no airflow would not be acceptable. Note also that resistors of this type are usually intended to be mounted onto a heatsink to achieve their rated continuous power dissipation.

RE46-2018  Wednesday 6 June 2018
EV Firewall TS Side Thickness 
Rules Reference T4.5.4
For the layer facing the tractive system side, can we have it made out of aluminium thicker than 0.7mm? As it seems to be only safer with a higher thickness, we would like to use 1mm thickness aluminium.

The allowable thickness of the Aluminium in the EV firewall per Clause T4.5.4, your proposal to be allowed to use 1.0 mm thick material, instead of the 0.7 mm maximum referred to in the rules sub-clause a), is acceptable.

RE44-2018  Thursday 7 June 2018
Jacking Point Enquiry
The rule T9.3.1.a states that the rear mounted aerodynamic device must not be further than 250mm rearward of the tyres. However the jacking bar is not an aerodynamic device, and so can it be assumed that it is not subject to rule T9.3.1.a, and therefore allowed to sit further than 250mm rearward of the tyres?
You have not explained why you need to locate the jacking bar so far rearward but, as it is not an aerodynamic device, it is not restricted in fore and aft location. You referred to a height of 70 mm. The underside of the tube must have a clearance of 75 mm minimum to the ground as measured at Technical Inspection. Located rearwards it may also be more difficult to ensure at 200 mm height off the ground with the specified “Quickjack” that the rear wheels do not touch the ground in full rebound. It must also not represent a hazard to officials or people moving around the vehicle and must meet all other specified functional requirements and represent sound engineering practice.

RE:48-2018  Monday 25 June 2018

Front Wing Mounting Clevis
Rules T3.20.4.b defines the mounting requirements for the IA Plate to the front bulkhead. Our design meets the minimum 8 x M8 bolts requirements, as stated in this clause.

We have added a clevis to the front surface of the IA Plate and front bulkhead for mounting the front wing. These clevis will require M6 bolts passing through the anti-intrusion plate and into the bulkhead. Does this addition of the clevis cause any implications on the vehicle satisfying all rules regarding the anti-intrusion plate?

The added bolts for the clevis will be additional to the minimum bolting requirements and therefore are acceptable for Clause T3.20.4. We note that your clevis is in front of the bulkhead and non-breakaway and will be in the Impact Attenuator Crush Zone. It must therefore be included in the IA test along with any other parts attached to it, which may add to the peak deceleration observed.

RE:49-2018  Monday 25 June 2018

The Accumulator Monitoring System - Open Fusible Link
Would the following detection method satisfy the Rule 2 of EV6.1.5 which requires that “The accumulator monitoring system can detect an open fusible link, and will shut down the electrical system by opening the AIRs if a fault is detected.“

If a fusible link does open, then the corresponding battery module will drop current at a faster rate than the rest of the stack. The AMS would look for a module current 10% lower than the average module current and assume a broken fusible link and open the AIR’s if true.

In the case there is a longer period for detection in a critical failure (cell short), it is expected the current would arc across the open fuse and then fuses to the other cells in the module. This would represent a large or complete voltage drop across the module and open the AIR’s in a very short time frame. Ruling safely in the module in the case of open fusible link in both cases.

In response to your question as to acceptable methods for compliance with the sub-clause 2 of EV6.1.5, we advise as follows:

The intention of rule EV6.1.5 is that the BMS must be able to detect an open circuit in the overall current path and shut down the vehicle immediately. This is intended to avoid a situation where an open-circuit fuse element is subjected to voltages significantly above its rating.
Where a vehicle is fitted with a battery pack comprised of multiple smaller cells in series parallel and each cell fitted with a fusible link, it is permitted to continue to operate the vehicle with a cell with an open link, provided the parallel links remain intact, as this will limit the voltage rise across the blown link. In the event of a failure of all parallel fusible links, the BMS must act to shut down the vehicle by opening the AIRs to prevent sustained over-voltage conditions being present across the fusible links.
The proposed Energus modules are therefore permitted provided the BMS can detect a total failure of all fusible links within the module.
In addition to the above, teams should be able to demonstrate a process through which a single open circuit fusible link can be detected after a period of time, i.e. over a charge-discharge cycle, so that long term operation of a accumulator with a damaged element can be avoided.
This should be documented in the FMEA.

RE:47-2018  Thursday 28 June 2018

Jacking Point 
Rule Reference: T6.6
The rule T9.3.1.a states that the rear mounted aerodynamic device must not be further than 250mm rearward of the tyres. However the jacking bar is not an aerodynamic device, and so can it be assumed that it is not subject to rule T9.3.1.a, and therefore allowed to sit further than 250mm rearward of the tyres?
You have not explained why you need to locate the jacking bar so far rearward but, as it is not an aerodynamic device, it is not restricted in fore and aft location. You referred to a height of 70 mm. The underside of the tube must have a clearance of 75 mm minimum to the ground as measured at Technical Inspection. Located rearwards it may also be more difficult to ensure at 200 mm height off the ground with the specified “Quickjack” that the rear wheels do not touch the ground in full rebound. It must also not represent a hazard to officials or people moving around the vehicle and must meet all other specified functional requirements and represent sound engineering practice.

RE: 48-2018   Sunday 24 June 2018 

Front Wing Mounting Clevis 
Rules T3.20.4.b defines the mounting requirements for the IA Plate to the front bulkhead. Our design meets the minimum 8 x M8 bolts requirements, as stated in this clause.

We have added a clevis to the front surface of the IA Plate and front bulkhead for mounting the front wing. These clevis will require M6 bolts passing through the anti-intrusion plate and into the bulkhead. Does this addition of the clevis cause any implications on the vehicle satisfying all rules regarding the anti-intrusion plate?

The added bolts for the clevis will be additional to the minimum bolting requirements and therefore are acceptable for Clause T3.20.4. We note that your clevis is in front of the bulkhead and non-breakaway and will be in the Impact Attenuator Crush Zone. It must therefore be included in the IA test along with any other parts attached to it, which may add to the peak deceleration observed.

 RE: 49-2018   Monday 25 June 2018
Attachment of GLV Batteries

Can the batteries but securely attached to another component of the car which is in-turn securely attached to the frame?Our current intention is to mount the batteries to our inverter housing – rather than mounting the batteries directly to the frame.

Your proposed approach to mounting to the frame via other securely mounted structure is acceptable as a general concept.

In using the inverter housing you should ensure selection of appropriate battery mounts and the overall GLV/Inverter Housing system weight is adequately supported by the frame attachments under all anticipated dynamic loads. You should be prepared to discuss/explain your design at the event.

RE: 50-2018  Tuesday 10 July 2018

Validity of Driver Harness

We currently use a FIA-rated harness manufactured in 2016 and the expiry year mentioned on the label is 2022. As per the rule, will our harness expire on 31st December 2022 or 31st December 2016?


The date punched into the harness/label on an FIA approved harness is the expiry date. Therefore in your case the year of expiry is 2022, provided that the harness is in a satisfactory and serviceable condition and not been involved in a crash.

RE: 51-2018   Tuesday 10 July 2018
Discharge Requirements for Battery Packs

We would like to request a clarification on behalf of all teams regarding the discharge requirements for battery packs.

There is no required rate of discharge stated, or time to discharge. Given how much energy these packs carry it could take a significant amount of time and we are concerned about the possible cost for appropriate equipment to dump the energy at the necessary rate. We felt that this may create additional hazard/safety issues.

One questions is, provided we can confidently deliver our car to scrutineering below the 50% SoC limit, will it be acceptable to present our charger as the discharge device? It has a discharge function that can safely discharge the pack but at a rate which is safe for its electrics (100s of watts) and taking hours to drop a sizeable chunk of charge.

We presume that once technical inspection of the accumulator tech is passed, there would be no need to redo TI tech, hence no real need for very high discharge rates?


The determination of appropriate discharge time is left up to the team, as it relates to internal policy with respect to working with energy storage. FSAE-A recommends that teams discharge batteries before working on live sections to reduce safety hazards associated with potential energy release, noting that hazards remain at all states of charge.

It is acceptable that the team present a discharge device that discharges over several hours to several days. No concession will be made to event schedule requirements to accommodate discharge activities.

Teams should investigate availability of a load bank, preferably one that could bring pack SOC down in 3-4 hours. Such devices are available commercially, but would also be fairly simple to construct using resistive heating elements if required. Any such device must be inspected by a qualified Australian electrician prior to use at the competition.

RE: 52-2018  Thursday 5 July 2018

Firewall Ducting Pass Through

This year we have designed a forced air-cooled accumulator cooling system. Ducts travel from the front of the vehicle, through the cockpit under the driver’s seat and pass through the firewall to the accumulator, with reference to T4.5.4:

a) Is it acceptable to adequately seal the pass though of the accumulator duct through the fire wall or;
b) Does the duct need to be considered as an additional panel of the firewall and hence be adequately sealed AND be comprised of tractive system material requirements with reference to T4.5.4.

If option a) is acceptable, ducts will consist of an electrically insulating material.

The intention of the firewall is to protect the driver from exposure to High Voltage and burns due to high temperatures, spilled liquids or fire inside the engine or tractive system compartment of the vehicle. Because the ducting will require a substantial unprotected hole in the firewall, it is required that the entire duct be constructed as a firewall as per option b) of your enquiry. Note that there should be no openings in the firewall facing toward the driver or into the driver’s compartment.

RE: 54-2018 Tuesday 10 July 2018
Applicable Standard for Testing Composite Accumulator Panels

Neither the rules nor the SES specify testing methods for accumulator panels. Consultation with composites technical and academic staff at our university has steered us away from applying monocoque 3 point bend test methods to accumulator panels due to the comparably vast differences in size and thickness of the accumulator panels to the monocoque panels (3mm vs 20mm thick).

Particular concerns surround the test span and the radius of the loading nose.

Is testing the panels to ASTM D790 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials suitable given the lack of direction given by the rules, and the greater applicability to the thin laminate?


You asked about testing methods for composite accumulators and said that the neither the rules nor SES specify testing method.

You must have overlooked Clause EV 3.4.8 (d) (i). It requires teams to use the standard testing method per T3.30.

See below and also you will note that in the SES it has already entered the span and sample dimensions (400mm and 275mm) in line with T3.30.

d. Composite monocoque chassis and/or accumulator containers must satisfy the following requirements:

i. Data obtained from the laminate perimeter shear strength and 3-point bending tests (T3.30) must be used for any strength calculations.

ii. Each attachment point requires steel backing plates with a minimum thickness of 2 mm. Alternate materials may be used for backing plates if

equivalency is approved.

iii. The calculations and physical test results must be included in the SES or SRCF.

RE: 57-2018 Monday 6 August 2018

Height of Gear Shifter
Since rule T4.6 does not specify a maximum height, provided the Gear shifter is entirely inside the envelope would that be suffice to show the Gear Shifter’s compliancy to rule T3.10.1?

It must be placed so that the drivers hands and control are always more than 50 mm inside the following envelope.  You need to also make sure it is comfortably located for the driver to operate while wearing wrist restraints at the event. 

The envelope runs up the lateral vertical plane of the side impact structure on each side of the vehicle and then around the line joining the outer surfaces of the Front and Main Roll Hoops, up over the upper part of the vehicle (the line in Figure 1a swept around the roll hoops).  You have to also consider the Figure at the top of Page 45 of the Rules for the front view and where it must be safely placed laterally.  

RE: 58-2018   Tuesday 7 August 2018

Cockpit Internal Cross Section Clarification
This question is in regard to the 50mm vertical slot of the template. Our steering system uses a 90-degree bevel gearbox, which when mounted to the car, will exist partially within this slot. The maximum width of the gearbox is less than 50mm and so it would not impede the template as the template passes through cockpit. Also we received confirmation last year that it was acceptable for the bevel gearbox and added shielded universal joints to pass through this slot (provided it does not impede the template) and would like to confirm that this will again be acceptable.

Regarding your rules enquiry on the cockpit cross section template, your interpretation is correct and the design will be acceptable with suitable shielding on moving parts.

RE: 59-2018  Thursday 16 August 2018

EV Firewall TS Side Thickness
Is it acceptable to use 3mm thick aluminium for the metal  layer of the tractive system firewall? 

While we have allowed a minor increase in thickness to 1mm to facilitate material availability we will not allow a further increase in the metal thickness beyond that.

RE: 60-2018 Monday 13 August 2018

EV Accumulator Connector as HVD Clarification

Can you please clarify how ‘remove’ is defined in the first underlined sentence above (‘removing an unobstructed and directly accessible element, fuse or connector’)? Does ‘remove’ mean it has to be completely removed from the car or disconnected?

From the second underlined sentence above (‘Being able to quickly disconnect the accumulator(s) from the rest of the tractive system by its connector(s) will satisfy this rule’), we think disconnection instead of complete removal shall be compliant and meets the intent of the rule but would like to confirm this understanding.

The expectation with the HVD is that I can be operated by first responders in an emergency to deactivate and isolate at least one pole of the accumulator so that they can be confident that the tractive system will not operate while they are working on the vehicle.

Generally the HVD is entirely removable from the vehicle, however, it is also acceptable for the HVD to be a plug that is separated from its housing with cables that remain attached to the vehicle.

If the HVD remains attached to the vehicle when disconnected, we would expect to be able to easily see the point of disconnection so that first responders can verify its disconnection.

RE: 62-2018  Friday 31 August 2018

Maintenance Plug Unique Configuration Clarification

Our Maintenance plugs, Amphenol Radlok satisfy the Positive Locking requirement

However, we are unsure if they will satisfy EV3.3.3 rule, due to 3 of our cables between cells stack could be connected to the wrong cell stack, due to being a greater length.

For example, our Maintenance Plug between the Cell Stack 2 and 3, could potentially be connected between Cell Stack 1 and 2 due to its length.

We feel that we meet the intent of this rule, yet not the wording.

Provisions have been made to reduce the likelihood of our trained team members wiring up the accumulator in the wrong configuration; all cell segment connectors are uniquely colour coded and labelled “positive” or “negative”. Would you recommend that we still amend our design to satisfy rule EV3.3.3?

The intent of the rule EV3.3.3 is to prevent accidental connection of cells in a manner that might cause a safety issue for the operation of the vehicle. In particular, it is of concern if it is possible to reverse polarity of a segment of the pack, or to accidently create a short circuit within the pack.

You should conduct a thorough risk assessment for the design of your pack and asses what dangerous conditions might occur should the plugs be installed incorrectly as might occur with your long cables. If you can demonstrate that no safety issues can arise on incorrect connection, your current design will be acceptable.

If it is possible, however, for a dangerous condition to occur, you must redesign your battery pack or the plug connectors to ensure it is physically impossible to achieve an incorrect installation of the maintenance plugs.

Note that a document assembly procedure and trained operators are both excellent steps to take but they will not be accepted alone as an appropriate mitigation strategy.

RE: 63-2018  Friday 31 August 2018

EV Accumulator Temperature Sensor


We would like to clarify if the following approach would be rule compliant:

The cells we are using are pre-packaged 7 18650 cylindrical cells connected in parallel as shown in the picture below. There are 3 temperature sensors sitting on the negative busbar in each of the cell blocks. From top to bottom, the first sensor sits in between the 1st and 2nd cell and is within 10mm away from either negative terminals as required by EV3.6.3. The second sensor monitors the 3rd and 4th cell and the last sensor monitors the 6th and 7th cell. The sensors are Zener diode like sensors and are connected in parallel internally. Therefore, the voltage read will always be the lowest voltage among three and according to the voltage-temperature relationship attached below. The temperature read will always be the highest temperature. Hence 85.7% of the cells are monitored in each cell block.

We would like to externally connect all the temperature sensors within each segment in parallel. This is the same as how the sensors are connected inside the cell blocks and will result in one reading per segment corresponding to the highest cell temperature in that segment. This way we are still monitoring 85.7% of the cell temperatures.

FSAE has previously accepted using the inbuilt temperature monitoring devices within the cell pack provided by Energus in which three of the temperature measurement devices are connected together in parallel, as this can give a reasonable estimate of the maximum temperature within the that cell group.

When connecting these devices together in parallel in large numbers, the total leakage current of the diodes will dominate any individual sensor detecting high temperatures, and it will be impossible to detect the small variances in overall voltage needed to detect an issue.

Finally, you should consider how you would demonstrate the correct functioning of the temperature monitoring devices during scrutineering. If you have a single temperature readout, it will be difficult to show that you are appropriately monitoring the entire pack.

Your proposal to connect the cell monitoring sensors together in parallel across the entire AMS is therefore not acceptable.

RE: 64-2018  Friday 31 August 2018

Intake Manifold Mounting Enquiry

The last sentence of rule IC1.9.1 b. is an example of an OEM exception to a rule, in this case prohibiting the use of plastic fuel rails.

Would the use of an OEM unmodified mounting method for the intake manifold be an exception to the above rule (IC1.4.3) in the same way that OEM plastic fuel rails are an exception to rule (IC1.9.1 b.)? An image describing this OEM mounting method can be seen below.

If this is not the case, how many mechanical fasteners are required on both the engine and intake sides of the required bracket?

The dispensation for unmodified OE use applies only to the Fuel Rail. The loads on the manifold may be quite different to the OE design in your installation due to mechanical configuration, engine mounting and engine tuning.

We cannot give you direct design advice but you should be able to develop a sound engineering response. Many teams in this situation use metal straps bolted to both manifold and cylinder head or other clamping device.

RE: 65-2018  Thursday 30 August 2018

Alternative Material Accumulator Panel Testing

T3.30 seems an inadequate requirement for obtaining material data as required by EV3.4.8.d.i

T3.30 is specifically designed for equivalency testing of monocoque regions, as evidenced by its title “Monocoque Laminate Testing”. This testing configuration is not appropriate for equivalency for an accumulator box as the test explicitly calls for two side impact baseline steel tubes to be tested, where as baseline accumulator panels are thin steel sheet as per EV3.4.6.

Further, the testing of such thin laminates over a 400 mm span does not result in material failure due to the excessive deformation (refer Figure 1). The attached test results (refer Figure 2) show that a bending test span of 400mm, resulting in a span:thickness ratio in excess of 100:1, is not appropriate for testing thin panels. For reference, Figure 3 shows a test sample of the same material and thickness performed to ASTM D790.

Is it permissible to use an international recognised testing standard to determine material properties? Such as:

  • ASTM D790 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
  • ISO 178:2010 Plastics -- Determination of flexural properties

Alternatively, can T3.30 be used with a modified span distance to accurately capture the design span? Can 1.25 mm steel plate be used as the equivalent baseline material instead of side impact tubes? Given it is not an input in SES, is energy absorption of the steel equivalent necessary?

The rules are not clear relating to monocoque use in areas other than side impact.  The two tube comparison applies for side impact.  Per clause T3.30.1 in other areas the equivalency must be to the “primary structure regions of the chassis” in the area the laminate is used.   Therefore for the accumulator material it must be equivalent to 1.25 mm Steel.    

You should show equivalence in ultimate strength and shear strength of the laminate to 1.25 mm Steel in your submission.   As it is not a required input for the SES, energy absorption will not be required.  

With appropriate support documentation you may use either a revised span or the ASTM test method for strength testing but ensuring an accurate comparison to steel under the method used. As penetration of the accumulator is a concern, use of the punch through shear test per T3.30.5 is still required.

RE: 66-2018  Thursday 30 August 2018

Firewall T4.5 
Our monocoque chassis has an extended lip coming off the shoulder bar. As this lip is part of the chassis, is it exempt from the insulation requirements?

Further, the seatback flange is laminated to the chassis. Does this have to be constructed as firewall or is this also exempt from these requirements as it is part of the chassis?

The key question here is whether the parts are an integral part of the chassis or do they form part of the required barrier between the driver and the tractive system components?   If they are part of the chassis, then they must still comply with EV4.3, if required by their location.

If they are there to form part of the barrier/seat back, then those parts would need to comply with the barrier dual layer requirements or be covered by the seat back.

RE: 67-2018  Saturday 8 September 2018

Accelerator Pedal Position Sensor - APPS
Regarding the rule T10.3.6 (fsg rulebook), we are planning to use two similar linear potentiometer but will invert the transfer function of one of them. Our potentiometer works like a simple potential divider so if we exchange the power and ground line for one of them, its transfer function will be inverted. For example, for a 10 V supply line, our working range is 1-3V, so for the inverted sensor, the working range becomes 9-7V. Will this method be rule compliant?

It is not acceptable to have the second power supply simply using an inverted function.

The intent of this rule is to ensure no common failure mode of the power supply circuit can occur that could result in the sensors agreeing with each other at anything other than the zero position.

Generally, teams would take one supply feed from the battery, then split it in the throttle circuit so that it is supplied by two separate power regulators. GND-5V and GND-12V are popular choices. Both sensors will then agree with each other at zero volts, 50% will be 2.5 volts on one and 6V on the other and 100% will be 5V and 12V. If both sensors get tied together, to ground or to either supply, the circuitry will see them as disagreeing and put the car into a fault state and shut off the motor.

Inverting the power supplies as suggested is generally not OK as there is a risk of the sensors agreeing with each other at some mid-point. Creating the second supply as a negative reference from the +12V supply, actually gives the same transfer function as the other supply, just from a different reference.

RE: 68-2018  Friday 14 September 2018

Firewall

I wanted to ask the procedure of this test. Is it done on a sample plate of firewall with both layer in place and then applying the load condition as mentioned in the rule or is it done in some other way. Please clarify

The test is not performed at inspection unless the scrutineers have concerns with your firewall design or the sample which you are required to bring to Technical Inspection. It would be carried out with both layers in place and the penetration requirement relates to ensuring that the screwdriver will not contact the aluminium. If you follow the requirements for the firewall construction as contained in the rules you should have no problems in meeting the requirements. You can of course carry out your own tests to ensure compliance on representative two layer samples.

RE: 69-2018  Friday 14 September 2018
Standard Impact Attenuator Structural Adhesive Bonding Test

 
   


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