What We Do and Our Approach: Engineering Design Support, Technical Evaluations and Analysis

TR3

Technical Review 3 - Frequency Response Analysis

As part of a full structural evaluation, a component within an off-highway vehicle had been shown to be susceptible to vibration induced fatigue damage. A steady-state response of the component was carried out in the frequency domain. In-service testing showed that a single input frequency dominated and this was provided as a ground excitation to the analysis model. (The surrounding structure had been shown to have modes well above this excitation frequency and so was not included in the model.)

 Graphs are plotted below of stress vs. frequency at a critial node. This allows critical frequencies to be identified, at  which a full stress analysis can be carried out.

Pilot studies were undertaken to investigate the effect of modelling assumptions on the results. One of these was an assessment of the effect of damping values chosen. Analyses were then conducted using differing damping values to quantify the effect, as shown in the second figure.