Numerical simulation of breast deformation under static conditions

The finite element (FE) simulation of breast biomechanics is essentially a nonlinear analysis, not only due to the nonuniform geometry but also due to the varying material properties. Several researchers (Kruse et al. 2000; Van Houten et al. 2003; Sinkus et al. 2005) have shown a high degree of nonlinearity in elastic modulus of breast tissues. For instance, Van Houten et al. (2003) summarised some of the researchworks for themeasurement ofYoung’smodulus and indicated a large variation due to the difference in types of tissues. Samani et al. (2003), however, developed a technique for an inverse identification of elastic modulus. They obtained the force–displacement curve through indentation over small specimens and then by using FE analysis, they estimated Young’s modulus. In recent years, some authors (Azar et al. 2001; Rajagopal et al. 2006) have kept their focus on FE modelling of breast deformation. Azar et al. (2001), for example, developed a deformable FE model of the breast to predict the deformations under external perturbations. While Rajagopal et al. (2006) compared the FEmodel with silicon gel phantoms to calculate the reference state of the breast. Li et al. (2003) studied a 3D biomechanical model of a female body and performed numerical simulation of the bra and breast interactions. They showed that the FE model can be used as a tool for designing and optimising the bra structure as well as the material. With an aim of optimising the design of a sports bra, the numerical simulation of breast deformation for three different female subjects has been performed in this work. A generalised approach has been used for the first time to develop the FE mesh for the breast in a reference state, and the gravitational loads were applied later so as to capture the deformation behaviour and estimate the material properties.