scope:

Introduction

Note: Nothing in this standard supercedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose. This procedure evaluates the structural durability of a vehicle by subjecting it to real time load and displacement profiles. These profiles are designed and developed to represent a road durability test at the proving ground. This procedure describes the test development process and durability test execution.

Applicability.

This procedure can be used to develop or validate the structural durability of a vehicle and its subsystems which are sensitive to road input and driveline torque reactions. These subsystems typically include chassis, body and driveline mounting structures. Components which are not sensitive to fatigue damage from road inputs may not experience the same level of correlation.

This procedure does not provide a total vehicle durability test. No powertrain or electrical system operation is included. Degradation modes of rotating components such as wheel bearings are not accurately reproduced. Environmental factors such as elevated temperature, humidity and dust are generally not included, except for special exposures for specific components. Degradation modes related to exposure time are usually not accurately reproduced.

This procedure can be used for passenger cars, Sport Utility Vehicle (SUV) or trucks. The Gross Vehicle Mass (GVM) of the vehicle determines which road simulator can be used. For example, a road simulator the: MTS 329 Light Truck (LT) (see Appendix G, Figure G1 and Figure G2) can be used for vehicles up to 5500 kg GVM, or a MTS 329 Passenger Car (PC) road simulator (see Appendix G, Figure G3 and Figure G4) can be used for vehicles up to 2700 kg GVM. Under some conditions, certain road events still may not be fully achievable even if these mass capacities are adhered to. If another type of road simulator is used, the user must verify that the mass capacity, force capability and displacement capability is sufficient to evaluate the test vehicle.

Remarks.

This procedure is primarily intended for laboratory test engineers and technicians. It does not cover every possible aspect of road simulation testing, and is not to be used as a standalone procedure. Successful road simulation testing inherently requires engineering judgment, and the ability to recognize and solve problems which are unexpected and/or complex.

The process diagram for real time project planning is located in Appendix A, Figure A1. The process diagram for a full vehicle road simulation test is located in Appendix B, Figure B1.

This procedure simulates road induced loading. These loads induce fatigue, interference and wear on the vehicle structure and subsystems.

This procedure reproduces one test equivalent of fatigue exposure in less time than it takes to perform the equivalent road durability test (see 3.4 for test time estimates).

This procedure typically requires a Road Load Data Acquisition (RLDA) or Virtual Road Load Data Acquisition (vRLDA), drive file development and correlation evaluation. The time required can be reduced if previously developed drive files can be used or modified, but this approach may result in reduced correlation to the proving ground road durability test.

This procedure refers to other procedures which contain detailed information that is closely tied to specific equipment or software. These procedures are intended to be used with guidance from experienced personnel (see 2.2 for details).

This procedure is intended to produce a laboratory road simulation for a specific vehicle configuration. A set of drive files will closely reproduce responses from remote parameter and correlation transducers for a vehicle with a specific combination of ballast condition, ballast position, body stiffness distribution and chassis components. If any of these characteristics are changed, the laboratory to road correlation may be reduced. Experience has shown that the reduced correlation is minimized under some conditions, such as a small change in shock absorber damping or body stiffness distribution. If the areas of interest are remote from the suspension to body interfaces, the risk can be further reduced.