骨组织准静态和动态压缩试验与本构模型研究

Study on quasi-static and dynamic compression tests and constitutive model of bone tissue

为了研究骨组织在不同应变率下的力学性能并建立本构模型,使用万能试验机与分离式霍普金森压杆(Split Hopkinson Pressure Bar,SHPB)对牛股骨开展了准静态和动态压缩试验,获得了不同应变率下的应力-应变曲线,并采用损伤型ZWT非线性黏弹性本构模型对试验数据进行拟合,从而确定骨组织本构模型参数。试验结果表明,牛股骨应力-应变曲线呈非线性特征和应变率效应,动态加载的弹性模量、极限强度远大于准静态加载,破坏应变随应变率增加而有所下降,呈现冲击脆化特征。对骨的损伤型ZWT本构模型进行参数拟合,发现该模型拟合曲线与试验曲线相比较具有较好的一致性,反求获得的相关材料参数与本构模型可用于高速冲击有限元仿真中的硬骨材料与带损伤的骨折模型。

In order to study the mechanical properties of bone tissue at different strain rates and establish a constitutive model.This paper used universal testing machine and split Hopkinson pressure bar(Split Hopkinson Pressure Bar,SHPB)to carry out quasi-static and impact compression tests on bovine femur,consequently obtained the stress-strain curves at different strain rates,and then used the damage-modified ZWT nonlinear viscoelastic constitutive model to fit the test data to determine the parameters of the bone tissue constitutive model.The experimental results show that the stress-strain curves of bovine femur display nonlinear characteristics and strain rate effects.The elastic modulus and ultimate strength of dynamic loading are much larger than those of quasi-static loading,while the failure strain decreases with the increase of strain rate,showing impact embrittlement feature.The results of the study show that by parameter fitting the bone-damaged ZWT constitutive model,the fitting curve of the model has a better consistency compared with the test curve.The relevant material parameters and constitutive models obtained by the reverse calculation can be used for hard bone materials and fracture models with damage in high-speed impact finite element simulation.