Simulation of Seat Ride Performance as Influenced by the Mechanical Impedance of the test Load

The ride performance of: two off-highway operator seats was simulated on a PC using TK Solver Plus^™ and Tutsim^™*. The narrow band random input acceleration to the model conformed to the requirements of the Class 1 Agricultural Tractor spectrum per SAE J1386 JAN86.

The purpose of the study was to determine the influence of operator subject (test load) mechanical impedance on seat ride performance. Specifically is it feasible to replace human test subjects with a rigid mass or simplified impedance model?

The results indicate that a rigid mass would result in much higher weighted rms acceleration (per J1013) than would a human subject. However, a single-degree-of-freedom (SDOF) seat load produced a seat response comparable to the response for a more complex two-degree-of-freedom (2DOF) model simulating human mechanical impedance up to 10 Hz.