Research On Dynamic Impact Damage Constitutive Model And Behavior Characteristics Of Viscoelastic Materials

China has a vast territory and is prone to frequent natural disasters.Developing highquality emergency rescue equipment is an important means of responding to major natural disasters.Viscoelastic buffer systems are widely used in vibration reduction mechanisms of emergency rescue equipment,often in a multi variable coupling mechanical environment of high speed,heavy load,impact,variable temperature,and frequency conversion,resulting in significant degradation of the buffer performance of the viscoelastic buffer system,seriously affecting rescue efficiency and safety.The degradation of the performance of viscoelastic cushioning systems is a macroscopic manifestation of damage to viscoelastic damping materials.Therefore,exploring the damage behavior characteristics of viscoelastic materials under heavy load impact loads has become an important issue that urgently needs to be addressed in the controllable development of new generation emergency rescue equipment.In order to explore the dynamic mechanical behavior and damage behavior characteristics of viscoelastic materials under heavy load impact conditions,this paper conducted research on constitutive modeling,dynamic damage modeling,and multiple impact characteristics of viscoelastic materials.The main research work is as follows:(1)Research on Viscoelastic Fractional Order Constitutive Model and Impact Characteristics.The viscosity coefficient was introduced to modify the viscoelastic fractional order constitutive model to describe the mechanical behavior characteristics of viscoelastic materials under impact loads.The parameter characteristics of the model were analyzed,and the mapping relationship between the stress-strain curve of the material under impact load and the order of the variable fraction in the model was determined,verifying the model’s ability to characterize the impact mechanical behavior characteristics of viscoelastic materials.The results indicate that the modified viscoelastic fractional order constitutive model can accurately describe the impact mechanical behavior characteristics of viscoelastic materials in a nondestructive state,with fewer parameters and clear physical significance.(2)Research on the Dynamic Damage Behavior Characteristics of Viscoelastic Variational Fractional Order.Based on the strain equivalence principle,a viscoelastic variable fractional order damage constitutive model was established by introducing a damage factor and combining the modified viscoelastic variable fractional order constitutive model for the whole process evolution of dynamic damage behavior of materials under impact loading.Fitting the stress-strain curves of viscoelastic materials under different impact pressures,the relative errors are all within 5%.Analyzed the damage behavior characteristics of viscoelastic materials under impact loads,and explored the influence of impact pressure on material damage behavior.We conducted an analysis of the micro impact damage characteristics of viscoelastic materials,conducted electron microscopy scanning experiments on silicone rubber and natural rubber after impact,analyzed the micro morphology characteristics of the two types of rubber under different impact pressures,and explored the influence of impact pressure on the location of the damage line area.(3)Research on the mechanical behavior and damage characteristics of viscoelastic multiple impacts.Multiple impact experiments were conducted on a specific rubber material for a shock absorber under different impact pressures.Through experimental curves,the mechanical behavior characteristics of viscoelastic materials under multiple impacts under different impact pressures were analyzed.By analyzing the changes in secant modulus after multiple impacts,the degradation trend of viscoelastic material properties was analyzed;Based on the viscoelastic variable fractional order damage constitutive model,the damage behavior characteristics and cumulative damage effects of materials during multiple impact processes were analyzed.