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This paper describes the procedure of root cause analysis and evaluation of the life of a component that is prone to fatigue failures. The durability testing of components subjected to continuous vibrations in their operating conditions tend to fail after long period of exposure. This makes it difficult and time consuming to test and analyse them in the actual operating conditions. This paper establishes a method of accelerated durability testing for failure modes and life cycle based on the results of Frequency Response Function and modal analysis. This helped in reducing the product development / improvement time.

The duration for the development of a new vehicle model is continuously decreasing. This does not permit adequate time for proving component assemblies and vehicles to be evaluated for durability by conventional measures. However, increasing competition and quality consciousness calls for an assured life with a high degree of confidence. This has forced the test engineers to look for techniques for accelerating the durability evaluation. The technique calls for concepts for compressing the evaluation time. This can be achieved by compression in both time as well as frequency domain. Further, it also calls for correct techniques for the mixing of roads, extrapolation of data acquired over a small distance to the vehicle life, evaluation and elimination of non or less damaging inputs, etc. This paper reviews some of the existing techniques and describes case studies of how accelerated testing can be applied in vehicle development.

One of the primary concern during assessment of structural integrity of vehicle bodies is the quality of joints used therein. The increased trend in vehicle weight reduction (through use of thin sheet panels) calls for more critical evaluation of the quality of such joints. The electric Resistance Spot Welding (RSW) is one of the largely used joining process for vehicle body structure. Besides the quality of sheet metal, the quality of RSW joints is largely governed by the process parameters e.g. weld current, hold time, squeeze time etc. The quality of RSW joints for durability can be assessed by mechanical strength and fatigue life. The paper presents a methodology for durability assessment of such joints using laboratory specimens and arriving at optimum values of process parameters to maximise the fatigue life. The methodology presented makes extensive use of Design of Experiment (DOE) techniques for better reliability of the results.

Road surface, payload and speed of the vehicle are important parameters, which affect the life of a vehicle. This paper discusses the relationship between road/load/speed and damage to the vehicle as a whole and automotive structure in particular. This will help the designer to understand non-linear relationship between different service conditions and damage and to arrive at realistic input spindle loads for design considerations. This will also help the evaluation engineer in the development of durability cycle by correlating different environmental conditions with actual service conditions.