This thesis describes a method of predicting transmissibility of seat cushion with human body on it from a simple mathematical model of human body and dynamic properties of the seat foam.
Dynamic characteristics of seated human body were investigated by measuring apparent masses of eight different subjects exposed to vertical vibration. Based on the measurements, a simple mathematical model of the human body was derived; three degree-of-freedom model. Also, complex stiffness of various foams was measured using indenter foot and base plate, and the results was reduced to a formula as function of preload at fixed dynamic amplitude that was equivalent to actual driving condition.
By using the dynamic stiffness and loss factor of foams, and three degree-of-freedom model of the human body, the transmissibility of the seat foam with human body on it was predicted mathematically over 1 to 30 Hz and compared with the actual measurements. It is shown that transmissibility could be predicted accurately in the frequency range of interest and, consequently, that the proposed technique is successful.
