Forensic Examination

This article focuses on the collapse of an excavating machine’s seat pedestal at the TU Electric Oak Hill strip mine near Tatum, Texas. It became serious when the excavator operator reported that the accident had injured his lower back. The strip mine’s insurance company brought a faulty product lawsuit against the manufacturer of the excavator. The seat assembly was modeled in an upright position using three-dimensional beam, plate/shell, and solid brick elements. The beam and plate/shell elements were used to represent the steel base of the seat and were defined using the material properties of steel from the software’s Material Library Manager. Giesen followed the event step-by-step on his computer screen and watched the force operating at points on the body in real time. It was remarkable to see the reverberation in very high mechanical frequency rippling up and down the backbone. The report of Giesen’s destructive examination and Mechanical Event Simulation results was one of many considerations in the subsequent settlement of the lawsuit.