Research On Dynamic Mechanical Properties Of Biological Soft Tissues

In order to study the mechanical response of human body subjected to high-speed impact(vehicle,blunt,bullet,explosion shock wave,etc.),dynamic mechanical testing of biological soft tissue materials is required,but due to its very soft and partially anisotropic properties,Sample preparation is also very difficult to test mechanical properties under dynamic impact.This paper mainly focuses on experiments,and explores the feasible methods for dynamic mechanical testing of biological soft tissue materials.The mechanical properties of pig chest and abdomen muscles,skin and fat are obtained,and the corresponding constitutive model is established.To make the experimental results more scientific and reasonable,firstly,fresh pig chest and abdomen tissue was used as experimental materials,and samples were prepared by using different size microtome and stored in Krebs solution for use.The MTS material testing machine was used to perform quasi-static stretching and compression experiments on pig chest and abdomen muscles,skin and fat respectively,and the stress-strain curve at low strain rate was obtained.In order to explore the feasible method for dynamic compression testing of biological soft tissue materials,20% mass fraction of ballistic gelatin at 10 °C was used as a sample to temporarily suspend biological soft tissue materials,and three improved methods based on Hopkinson pressure bars were used respectively.The dynamic compression mechanical properties were tested to compare the advantages and disadvantages of the three methods.According to the experimental results,the test method using PVDF piezoelectric film sensor can obtain the dynamic mechanical properties of ballistic gelatin.On this basis,the PVDF piezoelectric film sensor was used to test the dynamics of the muscle,skin and fat of the pig's chest and abdomen,and the stress-strain curve under high strain was obtained.According to the theory of strain rate-dependent constitutive model,on the basis of the experimental results obtained,several hyperelastic constitutive models are firstly fitted,and the applicability of each model to the corresponding materials is summarized.Then,the strain rate related constitutive models of muscles in two directions were fitted,and the isotropic strain rate related constitutive models of fat and skin tissues were fitted,and the fitting results were basically better.The strain rate effect of each soft biomaterial is described.