Definition of the potential damage on automotive components and synthesis of technical specifications for vibration qualification tests through the LMS Test Lab Mission Synthesis module

摘要

The aim of this study is to establish criteria and methods to define the specification for the vibration tests of automotive components. Using the test tailoring theory and the LMS Test Lab Mission Synthesis module, it is possible to create vibration profiles to be reproduced on electro-mechanical shakers for the vibration test of the components. Their definition is based on acceleration data acquired on the engine, on the appropriate values of life time to be ensured for a reliable operation of the engine and on all possible conditions of use of the vehicle. We considered a high performance automotive multicylinder engine because it represents a very critical case for its components, due to the high vibration levels achieved during its operation life. First we deepened the knowledge of this potentially damaging environment through the analysis of the vibration levels occurring, by using experimental data acquired both from the test bench and from the car. At the same time we created a multibody virtual model, with flexible bodies, of the crank rod mechanism that provides the forces and their origin, making possible to reach a better characterization of the engine components damage causes. The characterization and the analysis of the operation environment made possible to use the mission synthesis techniques to define accurate test procedures and to synthesize suitable vibration profiles to qualify the components through single-axis tests. Using an almost-steady approach, we correlated, in terms of equivalent damage, typical vehicle transients during the road operation with full load runups or other regulated operations. This permitted to introduce a series of simplifications in the data acquisitions and in the necessary data for the profile synthesis of the test. A correlation between the on board data and the quasi-steady approach allowed us to validate the process and to define its application limits.