Dynamic Properties of the Biomechanical Model of the Human Body-Influence of Posture and Direction of Vibration Stress

Abstract

Previous studies have shown that exposure to whole-body vibration can interfere with comfort, activities, and health. In analogy to materials handling it is assumed that the elevated spinal forces are a crucial component in the pathogenesis of the health impairment. To estimate the forces a biomechanical model was developed. In the model the human trunk, neck and head, the legs, and the arms are represented by 27 rigid bodies. An additional body simulates the vibrating vehicle or machinery. The bodies are connected by visco-elastic joint elements. In total 106 force elements imitate the trunk, neck, and leg muscles. The motion equations were derived by means of the dynamics of systems of rigid bodies. Motions were simulated in different standing and sitting postures and in three vibration directions. The transfer functions between the accelerations of the surface or the seat and the spinal forces were computed. By means of these functions it can be shown that under the conditions investigated the compressive forces seem to be the dominant stressor between the forces transmitted in the lumbar spine. However, it cannot be stated that under horizontal vibration the health risk is only dependent from the compressive forces. Here the relationship with the shear strength of the spine being much lower than the compressive strength must be regarded.

Development of a two-dimensional dynamic model of the foot-ankle system exposed to vibration

“…Several lumped-parameter linear models have been proposed in the literature to describe the response of the upper limb (Rakheja et al, 2002, Dong et al, 2004, Dong et al, 2007, Adewusi et al, 2012, Dong et al, 2018 and of the whole body (Wei and Griffin, 1998;Wu et al, 1999;Matsumoto and Griffin, 2003;Fritz, 2005;Kim et al, 2005) to vibration. Models can be used to estimate the effectiveness of anti-vibration devices (Dong et al, 2009) or to reproduce the interaction between the vibrating surface and the human body (Tarabini et al, 2013;Busca et al, 2014).…”

Biodynamics of the human body under whole-body vibration: Synthesis of the reported data

“…The measures are most often expressed in terms of force-motion relations at the driving-point, namely, mechanical impedance, apparent mass and absorbed power, and flow of vibration through the body, such as seat-to-head and body segments vibration transmissibility. The measured biodynamic responses have been used to identify mechanical-equivalent properties of the exposed human body and critical frequency ranges associated with resonances of different body segments (e.g., Coermann, 1962;Suggs et al, 1969;Mertens, 1978;Dupuis and Zerlett, 1986;Panjabi et al, 1986;Sandover 1988;Donati and Bonthoux, 1983;El-Khatib et al, 1998) to understand the potential injury mechanisms (e.g., Liu et al, 1998;Hinz et al, 2002;Magnusson et al, 1993) and for deriving frequency-weightings for exposure assessments (e.g., Meister et al, 1984;Mansfield and Griffin, 1998a;Holmlund, 1998a, Rakheja et al, 2008), and to help developing and validating continuum and discrete distributed-parameter models (e.g., Von Gierke and Coermann, 1963;Suggs et al, 1969;Fairley and Griffin, 1989;Mertens, 1978;Fritz, 2005;Pankoke et al, 2001). These biodynamic models can be further used to help quantify and understand the distributed joint forces, tissue stresses, and strains that may be directly related to the vibration-induced injury and disorder mechanisms (e.g., Fritz 2000;Pankoke et al, 2001;Hinz et al, 2002), to help design better seats and anti-vibration systems (e.g., Stein and Múča, 2003;Paplukopoulos and Natsivas, 2007;Kruczek and Stribrsky, 2004;Rakheja et al, 2002a;Kerr, 1998;Sachse et al, 2003;Pernica, 1990;Ippili et al, 2008;…”

Influence of the Posture of the Trunk on the Spine Forces during Whole-Body Vibration

“…The properties of the biomechanical model were described in detail by Fritz (2000Fritz ( , 2005 for the standing and sitting posture. The model was fitted to the properties of the vibration exposed humans as described in the literature or the standards in the form of the apparent mass or the seat-to-head transmissibility (ISO 5982, 2001).…”

“…From this it results that with the increase of the vibration induced motions of the trunk the forces and torques in the spine increase too. Biomechanical model in the standing and sitting posture, schematic of the skeleton of the human trunk, neck, head, and legs and of the arms and viscera (᭜), the dashed lines indicate the position of the nine cuts between the rigid bodies of the trunk and neck (adapted from Fritz 2005).…”

“…Compared with the biomechanical model described by Fritz (2000Fritz ( , 2005 or Fritz and Schäfer (2010) the present model was modified at the following points:…”