Study On Interlaminar Cracking Mechanism Of Polyurethane Elastomer Sandwich Structure

Polyurethane elastomer sandwich structure materials are better in strength,vibration and noise reduction and other mechanical properties than the single isotropic material,but also have advantages of lightweight,high specific stiffness,build more simple,more superior functions and stronger safety performance.Under the support of the existing industrial technology,polyurethane elastomer sandwich structure materials can be used in ships,bridges,stadiums,floor systems and explosion-protection walls and many other aspects.In recent years,scholars have studied the problem of interlaminar failure,but there is little research on the constitutive relation and the sandwich structure of polyurethane elastomer.This paper is aimed at polyurethane elastomer material prepared in laboratory is used as sandwich and steel plate as SPS structure,to study the constitutive relations and the panel-core's interface crack problems.The main researches are as follows:1.Design the uniaxial tensile,shear and compression experiments of the materials,and convert the compression experimental data to biaxial tensile data,in order to describe the hyperelastic properties of polyurethane elastic materials.Then using the material mechanics experimental data fitted by the ABAQUS software to error analysis,we can obtain the accurate constitutive model parameters at different strain levels.At last,the applicability of each hyperelastic constitutive model to polyurethane elastic material is reviewed.2.Analyze and compare three different kinds of viscoelastic model,using the generalized Maxwell model to describe the mechanical properties of polyurethane elastomer,getting one-dimensional relaxation constitutive equation and Prony series relaxation modulus.We can get the three dimensional integral constitutive equation of polyurethane elastomer based on the Boltzmann superposition principle.The relaxation test data were used to arrange the normalized relaxation modulus,and the viscoelastic constitutive equation was fitted to get the third-order viscoelastic Prony series model parameters.3.Experimental study on two kinds of(DCB ? SLB)interlaminar cracking of polyurethane elastomer sandwich structures under three loading rates(1mm/min ?10mm/min?100mm/min),and observe the cracking of layers.Calculating the energy releaserate of test specimens and using the virtual crack closure technique to get the critical energy release rate of type I and type II.4.ABAQUS finite element simulation software and Cohesive elements are used to simulate the DCB and SLB experiment of polyurethane elastomer sandwich structure.Compare the simulation results with the experimental phenomena,analyze the cracking situation.