OPTIMIZATION OF THE CONTACT DAMPING AND STIFFNESS COEFFICIENTS TO MINIMIZE HUMAN-BODY VIBRATION

In this paper, a lumped mass human model is used to minimize the energ y absorption at the feet/hip level when the body is subjected to verti cal vibration. The contact forces are assumed unknown. By coupling the dynamic response of the body with certain objective criteria, the opt imum damping and stiffness coefficients of shoes/chairs are sought. Th e optimization technique is based on the quasi-Newton and finite-diffe rence? gradient method and is used to seek optimum coefficients of the contact forces in the solution of the body's response in the frequenc y domain. The criteria of acceleration, displacement and internal forc es response area swept for a range of 0-15 Hz form the basis of our si mulation study. In the seated/standing postures it is found that for e ach criteria the frequency response shifts the peak of resonance of ea ch body segment response from 4.5/3.67 Nz to 2.5/2.255 Hz. In addition , the tc,tal energy reduces drastically when the contact conditions ar e optimum. The method presented in this paper is useful in modeling th e medium of contacts and especially in controlling the effects of huma n body vibration.