Formulation of the Relationship between Tension Loading Rate and Internal Stress for Uni-Axel Bio-Materials

D. Zhou and G. McMurray (USA)


Viscoelastic solid, loading rate and maximum stress LIST OF SYMBOLS A0 Initial section area in step load case A00 Initial section area in ramp load case E1 Youngís modulus E2 Youngís modulus F0 Initial external force in step load case Fuσ Force to generate σu in constant stress rate conditions Fuε Force to generate σu in constant strain rate conditions F∞ Force at infinite time l Length at time t l0 Initial length in step load case l00 Initial length in ramp load case t Experimental


The formulation of the relationship among the external applied force, internal stress and strain of bio-material is difficult due to its non-linear properties. Thus for simplification, bio-material relaxation and creep under certain load are mainly discussed under step stress and strain functions. The goal of this study is to show the influence of the external force loading rate on the maximum magnitude of the internal stress or strain. The change of the stress and strain is studied based on the assumption that the volume of the material remains unchanged. The results are used to explain the failure of bio-materials happens at different tensile load under different loading rate. The problem is analyzed and verified using both computer and experimental results. This study provides the basis for the description of the dynamic properties of biomaterials.

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