brake manufacturers council - aftermarket dynamometer test. the test results, combined with...

This Brake Effectiveness Evaluation Procedure Guide for vehicles with Gross Vehicle Weight Rating below 3,500 kg uses test results from the SAE J2784 FMVSS 135 single‐ended inertia‐dynamometer test. The test results, combined with vehicle‐specific parameters and vehicle dynamics modeling, evaluate the BEEP® pass/fail criteria and predict the conformance confidence of a friction material with the Federal Motor Vehicle Safety Standard requirements for stopping distance. The computer model was validated using proving ground testing with fully‐instrumented vehicles.

Brake Effectiveness Evaluation Procedure SAE J2784 ― FMVSS 135

BRAKE MANUFACTURERS COUNCIL BMC TN–08001–S1

BMC TN 08001 ― S1 BEEP® Guide FMVSS 135 ― 5.01.09

BRAKE MANUFACTURERS COUNCIL | Friction Material Committee 2

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The BMC Friction Materials Committee resolves that replacement brake friction materials should not deteriorate vehicle braking performance below the applicable Federal Motor Vehicle Safety Standards, and recognizes that full‐vehicle or inertia‐dynamometer testing per SAE J2784 with peer‐reviewed engineering and computer analysis may be employed by manufacturers of replacement friction materials in making good‐faith efforts to determine FMVSS conformance confidence.

To implement this objective the BMC implemented the BEEP® voluntary certification program administered by SAE‐PRI. Being the only industry‐approved and peer‐reviewed program available to the industry, the BMC decided to enhance the BEEP® program with the addition of the SAE J2784 ‐ FMVSS 135 inertia dynamometer test procedure to assess the BEEP® pass/fail criteria for vehicles manufactured after 2001. These continuous efforts from the BMC align with the government’s strategic framework outlined on NHTSA Docket No. 2008‐0113.

The use of computer models, sound laboratory testing results, appropriate engineering analysis methods, and vehicle‐specific parameters, allows the brake or application engineer to predict vehicle performance and determine the level of conformance confidence for a given combination of friction materials (on the front and rear axles) relative to the requirements of the Federal Motor Vehicle Safety Standard ― FMVSS 135. Similar models are used throughout the automotive industry to expedite the development and evaluation of friction materials and brake systems while reducing the overall costs related to the testing activities and associated resources before formal release for regular production.

This Guide was developed after extensive proving ground testing per the FMVSS 135 with fully‐instrumented vehicles and laboratory testing per the SAE J2784 ― FMVSS 135 test procedure to ensure the robustness of the model.

To make certain of the coverage of different brake systems, the tests used two vehicle braking system configurations:

Crossover vehicle with Electronic Brake Proportioning; disc brake on both axles; Sedan vehicle with fixed brake proportioning; drum brake on the rear axle.

The test program included three different friction materials on each axle:

Original equipment friction material; Aftermarket high friction material; Aftermarket low friction material.

The methods presented on this technical note follow the objective of the Brake Manufacturers Council's Friction Material Committee ― BMC/FMC:

BRAKEMANUFACTURERSCOUNCILA Product Line Group ofMotor & EquipmentManufacturers Association

BRAKEMANUFACTURERSCOUNCILA Product Line Group ofMotor & EquipmentManufacturers Association

The BMC Friction Materials Committee resolves that replacement brake friction materials should not deteriorate vehicle braking performance below the applicable Federal Motor Vehicle Safety Standards, and recognizes that full-vehicle or inertia-dynamometer testing per J2784 with peer-reviewed engineering and computer analysis may be employed by manufacturers of replacement friction materials in making good-faith efforts to determine FMVSS conformance confidence.

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Figure 1 illustrates the different options for the type of brake events, test sections, and system conditions contemplated in the model.

FIGURE 1. TYPES OF BRAKE EVENTS, TEST SECTIONS, SYSTEM CONDITION, AND BRAKE SYSTEM CONFIGURATION FROM FMVSS 135

AND SAE J2784

BEEP using SAE J2784

BEEP using SAE J2784

Fully operational

Failed systems

UMTRI limitUMTRI limit

Deceleration-control at LLVW & GVWR

Deceleration-control at LLVW & GVWR

Pressure-control at GVWR

Pressure-control at GVWR

Power brake at GVWR

Power brake at GVWR

Hydraulic circuit at LLVW & GVWR

Hydraulic circuit at LLVW & GVWR

Diagonal (X) split

Front/Rear (II) split

Front brake

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The flowchart on figure 2 illustrates the main steps and inputs required to assess the different pass/fail criteria for the BEEP® model.

FIGURE 2. MAIN STEPS TO ASSESS THE BEEP® PASS/FAIL CRITERIA

2. BEEP® criteria for fully‐operational system

2.1. Ramp applications; University of Michigan Transportation Research Institute ― UMTRI limit during ramp applications to 12,000 kPa. Front brakes shall not generate a torque equivalent to a deceleration level above 1.0 g at LLVW and a brake pressure corresponding to 178 N of pedal force. This criterion applies only to vehicles without ABS or Electronic Brake Proportioning.

2.2. BEEP™ criteria for deceleration‐controlled or pressure‐controlled brake applications. The test brake shall develop a torque equivalent to the required sustained deceleration level from the corresponding section at GVWR or LLVW when using the baseline values from the OE material on the reference axle (non‐tested axle) without exceeding a pressure corresponding to 500 N of pedal force with the brake system fully operational.

3. BEEP™ criteria for failed systems

3.1. Pressure‐controlled brake applications — power brake or power assist unit failure. The test brake shall be able to develop a torque equivalent to the required sustained deceleration level from the power brake unit failure section at GVWR without exceeding a pressure corresponding to 500 N of pedal force with any brake power assist system fully depleted.

3.2. Deceleration‐controlled brake applications — hydraulic circuit failure

3.2.1. Front‐to‐rear (II) split. The test brake shall develop on the test axle (front or rear) a torque equivalent to the required sustained deceleration level from the hydraulic circuit failure sections at GVWR or LLVW without exceeding a pressure equivalent to 500 N of pedal force with the brake system fully operational.

3.2.2. Diagonal (X) split. The test brake shall be able to develop a torque equivalent to the required sustained deceleration level from the hydraulic circuit failure sections at GVWR or LLVW when using the baseline values from OE material on the reference axle without exceeding a pressure corresponding to 500 N of pedal force with the brake system fully operational.

SAE J2784 test•Brake pressure and torque behavior•Brake output torques

Vehicle design or floor‐check parameters•Weights and weight distribution•CG location, wheelbase •Brake pressure versus pedal force curves•Brake sizes (front and rear)

Vehicle dynamics•Dynamic weight transfer•G‐critical

BEEP® model calculations•Determine loading and brake system condition•Combined braking forces (front and rear) •Tire‐to‐road adhesion utilization on each axle•Determine limiting condition: brake torque output or adhesion utilization

Vehicle performance prediction•Estimate total vehicle deceleration•Determine conformance confidence to FMVSS



4. BEEP structural integrity criteria 4.1. Allowed: Detachment or fracture of any component, such as brake springs, brake lining material, other than minor cracks

that do not impair attachment of the friction material to the backing plate or shoe table; 4.2. Not allowed: Friction material tear out (complete detachment of lining from backing plate or shoe table) exceeding 10% of

any individual friction material.

5. Test report

A summary table indicating the pass/fail for each applicable BEEP® criteria. In addition, as the main report for each brake event with BEEP® criteria the test report shall indicate:

5.1. Attainable vehicle deceleration calculated for the vehicle with the OE friction material on the other axle (non‐tested axle);

5.2. Percentage margin of conformance (or non‐conformance) confidence with the applicable BEEP® criteria;

5.3. Except for the hot performance criteria #1 and #2 which are very specific on the FMVSS 135 protocol, the actual BEEP® conformance confidence is reported for the brake application with the highest calculated deceleration value for that specific section. This follows the FMVSS criteria that "at least one stop" needs to fulfill the requirement.

Tables 1 and 2 show sample summary with the applicable BEEP® pass/fail criteria for friction products meeting and not meeting all the BEEP® requirements for a vehicle with EBP and with non‐ABS fixed rear brake proportioning, respectively.

TABLE 1. SUMMARY TABLE WITH TEST RESULTS FROM A TEST MEETING ALL BEEP® CRITERIA― FMVSS 135 TEST ON FRONT BRAKE



TABLE 2. SUMMARY TABLE WITH TEST RESULTS FROM A TEST NOT MEETING ALL BEEP® CRITERIA― FMVSS 135 TEST ON FRONT BRAKE



Appendix A

Minimum performance requirements per the FMVSS 135

Table A.1 shows the test sequence during a SAE J2784 ― FMVSS 135 inertia–dynamometer laboratory test along with the maximum stopping distance allowed during the vehicle test and the corresponding sustained deceleration level.

In order to obtain the different sustained deceleration levels, the BEEP® model uses the nominal test conditions (brake force build up time and braking speed) along with the maximum stopping distance allowed for the specific section. The general calculation for the maximum allowed stopping distance in meters (and minimum stopping distance for the recovery performance section) during the vehicle test uses equation A.1.

2VbVaS ⋅+⋅≤ Equation A.1 Where: a coefficient that equals 0.1 to account for the distance traveled during braking force buildup time V is the braking speed in km/h b coefficient that varies as a function of the maximum stopping distance allowed. Coefficient b is related to the sustained

vehicle deceleration 135a per equation A.2. The individual b values are specified on the FMVSS 135 protocol for each section.

ba

⋅⋅=

81.992.251

135 Equation A.2

TABLE A.1. BEEP® CRITERIA USING SAE J2784 FMVSS 135 INERTIA DYNAMOMETER TEST PROCEDURE

Section Number

FMVSS 135 Reference Braking Speed

V [km/h]

Brake Application Control

(IBT, Cycle Time, or Distance)

FMVSS 135 Required stopping

distance

S [m]

BEEP® Required deceleration level

135a [g]

10 7.1 Burnish at GVWR 80 IBT = 100 °C — —

20 7.4 (1) 3 500 kPa Adhesion Utilization Ramps at GVWR

50 IBT = 65 °C first, then 100 °C — —

30 7.4 (2) 12 000 kPa Adhesion Utilization Ramps at GVWR

100 IBT = 65 °C first, then 100 °C — —

40 7.5 Cold Effectiveness at GVWR 100 IBT = 100 °C < 70 > 0.66

50 7.6 High Speed Effectiveness at GVWR 160 IBT = 100 °C < 187.5 > 0.59

(80% Vmax for Vmax < 200 km/h)

<0.1∙V+0.0067∙V2

60 7.5 Cold Effectiveness at LLVW 100 IBT = 100 °C < 70 > 0.66

70 7.6 High Speed Effectiveness at LLVW 160 IBT = 100 °C < 187.5 > 0.59

(80% Vmax for Vmax < 200 km/h)

<0.1∙V+0.0067∙V2

80 7.8 Failed Antilock System at LLVW 100 IBT = 100 °C < 85 —

90.a 7.10 Hydraulic Circuit Failure at LLVW for front brakes

100 IBT = 100 °C < 168 > 0.25

90.b 7.10 Hydraulic Circuit Failure at LLVW for rear brakes

100 IBT = 100 °C < 168 > 0.25

100.a 7.10 Hydraulic Circuit Failure at GVWR for front brakes

100 IBT = 100 °C < 168 > 0.25

100.b

7.10 Hydraulic Circuit Failure at GVWR for rear brakes

100 IBT = 100 °C < 168 > 0.25

110 7.8 Failed Antilock System at GVWR 100 IBT = 100 °C < 85 —

120 Cool Down at GVWR 5 Until 5 °C above cooling air temp — —



Section Number

FMVSS 135 Reference Braking Speed

V [km/h]

Brake Application Control

(IBT, Cycle Time, or Distance)

FMVSS 135 Required stopping

distance

S [m]

BEEP® Required deceleration level

135a [g]

130 Warm Up at GVWR 50 Until 65° at 60 seconds cycle time — —

140 7.11 Failed Power‐Brake Unit at GVWR 100 IBT = 65 °C first, then 100 °C < 168 > 0.25

160 7.13 Heating Snubs at GVWR1 120‐60 IBT = 55 °C first, then cycle time of 45 seconds

< 151 0.31 + 0.05

170 7.14‐1 First Hot Stop at GVWR2 100 20 seconds after the end of the last snub from section 160

< 110 > 0.39

170‐180 7.14 (‐1 / ‐2) First OR Second Hot Stop at GVWR

100 20 seconds after the end of section 170

< 89 > 0.50

190 7.15 Brake Cooling Stops at GVWR 50 Cycle distance = 1.5 km after the end of section 180

— —

200 7.16 Recovery Performance at GVWR3 100 Cycle distance = 1.5 km after the start last stop of section 190

50 – 86 0.98 – 0.46

210 7.17 Final Inspection for structural integrity –Not allowed: Friction material tear out (complete detachment of lining from backing plate or shoe table) exceeding 10% of any individual friction material

Bibliography

BMC, Aftermarket Friction Product Effectiveness Characterization Guide, BMC, Research Triangle, NC, 2002

Breuer, B. and Bill, K. H. Brake Technology Handbook, SAE, Warrendale, PA, 2008

Limpert, R. Brake Design and Safety, SAE, Warrendale, PA, 1999

NHTSA, 571.135 Standard No. 135—Light Vehicle Brake Systems, DOT, Washington DC, 2005

NHTSA Docket No. 2008‐0113. Recommended Best Importer Practices To Enhance The Safety Of Imported Motor Vehicles And Motor Vehicle Equipment, DOT, Washington DC, 2008

Robert Bosch GmbH, Safety, Comfort and Convenience Systems, John Wiley & Sons Ltd., West Sussex, England, 2006

SAE Brake Dynamometer Test Code Task Force, SAE J2784 FMVSS 135 inertia dynamometer test procedure, SAE, Warrendale, PA, 2007

Additional information:

www.brakecouncil.org

http://www.pri‐network.org/PRI/

www.linkeng.com

1 BEEP criteria not actual requirement for the FMVSS 135 vehicle test. 2 Using deceleration level equivalent to the maximum stopping distance allowed during the Cold Effectiveness section at GVWR at 100 km/h; section 7.5 . 3 Ditto footnote 2.

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