The human body behavior under vehicle vibrations

The influence of vertical vibrations on the human body is analyzed on the basis of models, where the main components and their characteristic properties are made evident. As a function of position of the body, there are considered models, having concentrated masses, elastic constraints and dampers. For a few models that are presented, the matrix differential equations of motion are written and the mathematical input-stateoutput model (M-ISO-M) is specified. On the basis of the adopted mathematical models, computer block diagrams are defined. Thus, for the study of behavior of the mechanical systems, calculus diagrams are elaborated, in order to make evident the connections between the blocks and the developments with the help of Math Lab simulation of the system response to a harmonic input signal. Also with the help of the AnyBody Modeling System software, a driving simulation had been made, resulting intense muscle activities by subjecting the human body to the vehicle vibrations and external forces. The concrete cases that are studied refer to real situations for which the system parameters are deduced by a methodology, previously specified. In each case, fixed by the program running, for each mass, the amplitude-pulsation characteristics are determined, making evident the resonance possibilities.