The effects of vertical and horizontal vibrations on the human body.

Vertical and horizontal vibrations of a 100 kg human have been investigated. A new mechanical model has been developed, and an analogous electric simulation has been carried out, which in turn has been analysed by using computer software (MICRO-CAP II). The vibration force comes from (a) hand, (b) seat and (c) combination of the two. The theoretical results obtained have been tabulated and are presented in a graphical manner. It has been found that the body segments (lower arm, head, torso, cervical spine and lumbar spine) are affected by horizontal vibrations when the input force (F(i)) comes from both hand and seat more than when (F(i)) comes from the seat alone. Similar results have been found also for the case of the lower arms and torso when the body is subjected to vertical vibrations. The head is affected by vertical vibrations when (F(i)) comes from the seat more than when (F(i)) comes from both hand and seat. An experimental set-up has been designed and measurements of vibrational signals from the human lower arm, head and torso have been carried out. Similar trends are shown for both theoretical results and experimental findings.