Deformation and Stress Analysis of Supported Buttock Contact

Abstract

Non-linear finite element analysis has been used to investigate the contact problem between a buttock and a cushion of varying properties. The buttock tissue has been modelled on the macroscale by assuming it to be a hyperelastic (rubber-like) material with properties that correspond to the overall buttock response. Both rigid and $exible cushions have been considered. The contact between the cushion and the buttock has been modelled assuming both friction and friction-jiree conditions. The effect of these parameters on the buttock-cushion deformation and the tissue compressive and shear stress distributions have been presented. This study forms part of work towards the development of body segment simulatorsfor use in investigations of seating and other support surfaces.

Finite Element Analysis for Evaluation of Pressure Ulcer on the Buttock: Development and Validation

“…Several such FE models have been developed [9], [11], [13], [15]- [19]. However, several intrinsic weaknesses are associated with these models.…”

Evaluation of a new sitting concept designed for prevention of pressure ulcer on the buttock using finite element analysis

“…There have been several attempts in using FE analysis to evaluate sitting induced mechanical response in deep tissue of the buttocks [5][6][7]11,19,23,24]. Chow and Odell (1978) [6], using a simple axi-symmetric buttock FE model, found that the buttock tissue experienced small deformation when using a floating support design cushion.…”

“…Chow and Odell (1978) [6], using a simple axi-symmetric buttock FE model, found that the buttock tissue experienced small deformation when using a floating support design cushion. Dabnichki et al (1994) [7], employing contact elements in a simple 2D FE buttock model, found that the maximal compressive stress and displacement generated close to the bony prominences depended on the surface conditions, with the rough compliant surface generating the least compressive stress and tissue deformation. Oomens et al (2003) [19], using a simple 2D FE model, also studied the mechanical responses of the deep tissues related to cushion properties.…”

“…This phenomenon may be the consequence of the incompressibility of the soft tissue. In this model, we used a first order polynomial elastic Moony-Rivlin model [7] with Poisson ratio ≅ 0.485 [15] to represent the nearly incompressive characteristic of biological tissue. Therefore, when some locations, such as the area beneath the ischial tuberosity, endure large compressive deformation, the soft tissue may be pushed to the neighboring locations, which results in a slight local increase of the tissue thickness.…”

“…Some studies suggested a need to establish the associations between external mechanical loads and the internal local mechanical condition of the tissue [6,7]. It is pointed out that the interface pressure measurements provide only a very small portion of the information to the overall problem [19] and help little for understanding the situation in deep tissues [4].…”