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Sitting Biomechanics Laboratory
Part of the |
Evaluating Sitting Load using the Established Buttock-Thigh Sitting FEM: Part I—Regular Sitting Posture
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Deformation of Tissues in the Sagital Plane The output of the FE analysis showed that the deformation induced by sitting pressure of 20.34 kPa was substantially different among muscle, fat, and skin. Generally, the deformation of the skin (1.87±1.77%, N = 42) was smaller than that in fat (33.79±2.17%, P<0.001, N = 42) and muscle (5.55±3.57%, P<0.001, N = 42) for the selected sagittal piece of buttock-thigh. The deformation of the fat layer was relatively uniform, while the deformation of the muscle layer varied. In muscle layer, the closer to the ischial tuberosity, the more the deformation was. The maximum deformation was seen in the regions underneath the bony prominence of ischial tuberosity (11.93±1.66%, N = 12). A typical anterior-posterior deformation (%) in the muscle layer in a sagittal section (Upper). Predicted deformation on the buttock-thigh soft tissues (Bottom) in this section. Large deformation is identified in fat and muscle in the region (circle in figure) immediately underneath the ischial tuberosity (IT). |
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FE Model Output for Stress Distribution Fig. A shows the distribution of the internal pressure predicted by FE analysis. For all layers, higher compressive pressure was found in the PM area of the buttock covering the ischial tuberosity. The range of high compressive pressure was 65~80kPa, 50~60kPa, and 55~65kPa, for skin, fat and muscle, respectively, in the area close to the bony prominence of ischial tuberosity. The pattern of the von-Mises stress distribution was, in general, similar to that of the pressure. Fig. B shows the distribution of the von-Mises stress for the entire buttock-thigh with the details of the results on the muscle close to the bony prominences. The range of high von-Mises stress was 50~80kPa, 35~45kPa, and 45~50kPa, for skin, fat and muscle, respectively. Internal pressure (A) and von Mises stress (B) distribution for the entire structure of the buttock-thigh. high pressure is identified in the fat and muscle in the region (circle in figure) immediately beneath the ischial tuberosity. |
Last updated
May 25, 2008 by Patton.
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