A Comparison of Time Domain and Frequency Domain Test Methods for Automotive Components 942279

Frequency domain testing has had limited use in the past for durability evaluations of automotive components. Recent advances and new perspectives now make it a viable option. Using frequency domain testing for components, test times can be greatly reduced, resulting in considerable savings of time, money, and resources. Quality can be built into the component, thus making real-time subsystem and full vehicle testing and development more meaningful.

Time domain testing historically started with block cycle histogram tests. Improved capabilities of computers, controllers, math procedures, and algorithms have led to real time simulation in the laboratory. Real time simulation is a time domain technique for duplicating real world environments using computer controlled multi-axial load inputs. It contains all phase information as in the recorded proving ground data. However, normal equipment limitations prevent the operation at higher frequencies. For time domain testing the test times are usually optimized by removing low energy levels and high frequencies. This can potentially lead to the elimination of damage causing events for components with high resonant frequencies.

Frequency domain testing approaches the problem from a different perspective. It maintains the frequency content and applied energy levels of the real-world conditions, but the phase differences between axes are not representative of the real world. However, in frequency domain testing it is possible to greatly reduce the test time by using standard techniques, while retaining the frequency content and the low energy levels.

There is always a question as to which test is suitable for each application. The use of both techniques is presented here as a comparison evaluation to aid in the decision making process of developing an appropriate test procedure.