ABSTRACT
A homogenous constitutive law was proposed for passive biomechanical behaviour of gallbladder (GB) walls based on the ellipsoid model in Chapter 5, 6 or 8. Five model constants in the law were determined inversely in finite element analysis (FEA) by using Abaqus and MATLAB optimisation program for ten GB samples in the refilling phase. A time-variable international bile pressure was specified to drive the refilling process. The anisotropic property in the passive state was identified by employing the ratio of the circumferential Young’s modulus and the longitudinal Yung’s modulus. It turns out that the constitutive law is applicable to GBs in the passive state. Most GB walls (seven of ten) exhibit circumferentially stiff anisotropic property, a few GB walls (two of ten) are nearly isotropic, one GB wall is with longitudinally stiff anisotropic property, depending on GB geometrical change during the refilling. The Young’s modulus ratio (with 60% success rate) may be an additional proper GB pain index potentially.
