Logarithmic rate based elasto-viscoplastic cyclic constitutive model for soft biological tissues.
Based on the logarithmic rate and piecewise linearization theory, a thermodynamically consistent elasto-viscoplastic constitutive model is developed in the framework of finite deformations to describe the nonlinear time-dependent biomechanical performances of soft biological tissues, such as nonlinear anisotropic monotonic stress-strain responses, stress relaxation, creep and ratchetting. In the proposed model, the soft biological tissue is assumed as a typical composites consisting of an isotropic matrix and anisotropic fiber aggregation. Accordingly, the free energy function and stress tensor are divided into two parts related to the matrix and fiber aggregation, respectively. The nonlinear biomechanical responses of the tissues are described by the piecewise linearization theory with hypo-elastic relations of fiber aggregation. The evolution equations of viscoplasticity are formulated from the dissipation inequalities by the co-directionality hypotheses. The anisotropy is considered in the hypo-elastic relations and viscoplastic flow rules by introducing some material parameters dependent on the loading direction. Then the capability of the proposed model to describe the nonlinear time-dependent deformation of soft biological tissues is verified by comparing the predictions with the corresponding experimental results of three tissues. It is seen that the predicted monotonic stress-strain responses, stress relaxation, creep and ratchetting of soft biological tissues are in good agreement with the corresponding experimental ones.
School of Architectural and Civil Engineering, Chengdu University, Chengdu 610106, PR China.
Yilin
Y
Zhu
State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, PR China. Electronic address: guozhengkang@126.com.
Guozheng
G
Kang
State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, PR China.
Chao
C
Yu
Department of Civil and Environmental Engineering, National University of Singapore, E1A-07-03, 1 Engineering Drive 2, Singapore 119260, Singapore.
Leong Hien
LH
Poh
D000818:Animals; D016880:Anisotropy; D001696:Biomechanical Phenomena; D002417:Cattle; D003238:Connective Tissue / Q000502:physiology; D004548:Elasticity; D008954:Models, Biological; D012879:Skin Physiological Phenomena; D013314:Stress, Mechanical; D013552:Swine; D014783:Viscosity
Anisotropy; Constitutive model; Ratchetting; Soft biological tissues; Time-dependence