Construction Of Adipose Tissue Material Constitutive Model And The Effect Of Obesity On Thoracic And Abdominal Injury

Motor vehicle traffic accident is an important factor causing children casualties.The existing child safety regulations and the child occupant restraint system are designed for children of standard weight.With the increasing number of obese children,it is necessary to study the injury mechanism of obese children in traffic accidents.The constitutive model and mechanical properties of adipose tissue are of great significance for the study of collision injury in obese population.In this paper,the biomechanical properties of adipose tissue are summarized from the aspect of mechanical experiments,and the adipose tissue is considered as homogenous,with symmetry in stretching and compression,non-linear mechanical response and strain rate-dependent characteristics of incompressible soft tissue.The finite element model of adipose tissue under low and medium strain rate was constructed,and four common lipid tissue materials were respectively applied to conduct unconstrained compression test simulation under different friction coefficients.The contact force output of each constitutive model of materials is positively correlated with the friction coefficient,and the effect of different constitutive models on the mechanical response is particularly significant.In the unrestrained compression test of adipose tissue,the static friction coefficient of 0.1 and the kinetic friction coefficient of 0.05 are reasonable.Under low and medium strain rate,the constitutive of Ogden hyperelastic material can adequately describe the biomechanical response of adipose tissue.The constitutive of Ogden hyperelastic material was adopted and the screening test was designed to determine the influence of various factors on the target response.By combining the finite element method with the optimization strategy,the parameters of adipose tissue materials were inversely solved by using the adaptive response surface method.The results show that the parameters of adipose tissue materials obtained by reverse estimation method are of great biofidelity.By constructing a detailed hierarchical finite element model for obese children,the effects of different degrees of obesity on the risk of chest and abdomen injuries in children were studied,and the constraint protection effect of two different types of child restraint systems on children with different levels of obesity was analyzed.The risk of chest and abdomen injury was positively correlated with BMI in the belt-positioning booster seat.With the increase of BMI,the risk of chest and abdomen injury increases first and then decreases,and the five-point restraint system has a better constraint protection effect on obese children.According to the basic model,the mass model and shape model can be obtained.The study found that obese children have a higher risk of injury to their chest,abdomen and lower limbs.Meanwhile,both quality and body shape have a certain degree of influence on the injury of obese children.Single compression ratio of chest and abdomen and chest acceleration cannot well reflect the injuries of obese children's crew.Integrated indicators such as V*C and FmaxCmax are more applicable to the evaluation of the injuries of chest and abdomen of obese children.