Applications of DSP to Explicit Dynamic FEA simulations of elastically-dominated impact problems

Explicit Dynamic Finite Element techniques are increasingly used for simula ting impact events of personal electronic devices such as portable phones a nd laptop computers. Unfortunately, the elastically-dominated impact behavi or of these devices greatly increases the tendency of Explicit Dynamic meth ods to calculate noisy solutions containing high-frequency ringing, especia lly for acceleration and contact-force data. For numerous reasons, transien t FEA results are often improperly recorded by the analyst, causing corrupt ion by aliasing. If aliasing is avoided, other sources of distortion can st ill occur. For example, Filtering or decimating Explicit Dynamic data typic ally requires extremely small normalized cutoff frequencies that can cause significant numerical problems for common DSP programs such as MATLAB. This paper presents techniques to combat the unique DSP-related challenges of E xplicit Dynamic data and then demonstrates them on a very challenging trans ient problem of a steel ball impacting a plastic LCD display in a portable phone, correlating simulation and experimental results.