Quasi-static Tensile Constitutive Model And Experimental Study Of Thermosetting Resin Materials

Resin mineral composite（RMC）is a kind of multiphase composite material,which uses resin as matrix,takes the broken stone or natural pebble as the basic skeleton,and then adds some other components,such as fiber（reinforcing component）,toughening agent,pulverized coal ash（defoamer）,etc.Resin mineral composite has the advantages of high strength,high stiffness,convenient design and processing,not easy to corrosion,good chemical stability and large area molding.It is an excellent material for manufacturing high-end machine bed.Resin system is the matrix of resin mineral composites,which mainly plays the role of bonding each component.Resin material has the advantages of low density,high specific strength,corrosion resistance,excellent viscoelasticity and large damping.It absorbs most of the energy in the vibration of RMC machine tools,and effectively reduces the vibration.It can be seen that the resin system plays an important role in the vibration reduction of RMC.The relationship between the quality ratio of the basic component of the resin system,epoxy resin（E51）and curing agent（593 curing agent）,is studied.The optimum ratio of epoxy resin to curing agent is determined by taking compressive strength as the index.In this paper,the quasi-static tensile tests of the epoxy resin with the rate of 2mm/s are carried out for the resin materials with the curing agent=3:1,3.3:1,3.5:1,3.7:1 and 4:1（mass ratio）,and the tensile strength of the resin is obtained under each proportion,and the optimal ratio of resin to curing agent is determined.The stress-strain test curve obtained by the test is analyzed in detail.Under the condition of the optimal proportion,the tensile tests of the resin materials with the strain rates of 0.000667s^-1 0.003333s^-1 and 0.00533s^-1 were carried out respectively.The viscoelastic behavior of resin materials under different strain rates was obtained by comparing the tensile stress-strain curves and the fracture section morphology.Then,the tensile stress-strain curves of three groups of different strain rates are fitted by using the generalized ZWT constitutive mode（i.e.the constitutive model of N Maxwell bodies in parallel with a nonlinear spring）.Here n is taken as 1,2,3 and 4 respectively.From the fitting effect,when n=4,the fitting effect is the best.Finally,n=4.The specific values of the constitutive parameters are obtained at the same time when n=4.One-dimensional generalized ZWT constitutive model is extended to three-dimensional form and three-dimensional incremental form.The three-dimensional incremental form of the derivation process of the constitutive equation is written into the MATLAB program,and the determined one-dimensional constitutive parameters are substituted into the matlab program for fitting and correction,and the specific values of the three-dimensional constitutive parameters are obtained.Then,the incremental form of the three-dimensional constitutive model is written into ABAQUS UMAT subroutine,and three groups of tensile experiments under different strain rates are simulated in ABAQUS software.The tensile stress contour characteristics of resin specimens under different strain rates were analyzed.