Constitutive Relationship Of Anisotropic Composites And Its Application In A FEM Simulation Of The Dynamic Response Within The X-ray Radiation In 3D Condition

With significant advantages of high strength,high modulus and designable performances,the anisotropic composite materials,like Carbon Fiber Reinforced Polymer(CFRP),have been widely used in the design and manufacture of spacecraft structural parts.Still,when the spacecraft is working in the outer space,it may encounter highenergy X-ray pulses radiation generated by nuclear explosion.The surface skin of spacecraft made by composite material may suffering the vaporization,ablation,and spallation;besides,the thermal shock wave may generate and propagate inside the material.All these phenomena mentioned above may seriously threaten the spacecraft.Therefore,it is very important to study the dynamic response of CFRP materials induced by X-ray pulse radiation.However,the anisotropic composite itself has a complex structure,and its dynamic response under X-ray pulse radiation is very complicated,as it involves not only the constitutive model and the description about the model of equation of state,but also some complicated procedure,like vaporization phase change and tensile fracture.Besides,when using numerical method such as FEM to solve this problem,the couple between energy deposition and dynamic response simulation also needs to be considered.In this work,we focused on the three-dimensional numerical simulation of the dynamic response of an anisotropic CFRP material under X-ray radiation,which located at the aerospace field of the application of anisotropic composite materials.It was aiming to solve the anti-radiation reinforcement evaluation technology of materials.Main work contributions and research conclusions in this thesis are listed as below:1.The high-altitude nuclear explosion X-ray is approximated to a certain temperature of blackbody radiation,and then the energy distribution of photons with wavelength at different blackbody spectrum temperatures is derived.Based on the photoelectric effect and Compton scattering effect of the interaction between X-ray photons and targets,the mass absorption coefficients of aluminum and CFRP materials for photons in different wavelengths are derived.After that,an algorithm for calculating the energy deposition profile via calculating the integral of the energy flux vector area under three-dimensional conditions is proposed for the first time,by taking the finite-length cylindrical shell as an example.2.A three-dimensional elastoplastic dynamic constitutive model and equation of state of anisotropic materials are established.The stress-strain relationship is described by the generalized Hook law,and the plastic strain is calculated by the plastic flow rule.The pressure is described by the Grüneisen equation of state in compression state,and the PUFF equation is used to describe it in expansion state.We modified the above equation of state by considering the anisotropic mechanical properties of the material to overcome the uncoupling between equation of state and constitutive model.So that the modified equation of state can not only represent the nonlinear relationship between pressure and volume,but also reflect the anisotropic mechanical properties of the material.3.By using the explicit finite element method described by Lagrange viewpoint,A self-coded three dimensional X-ray thermal shockwave program TSHOCK3 D is compiled.According to the characteristics of the thermal shock calculation problem and the numerical method of single point Gauss integral,the corresponding correction scheme of artificial volume viscosity and hourglass viscosity is posted.In order to make sure that this program's structure is absolutely clear,we packaged the element operation function and the node operation function separately.In addition,the correctness of program dynamics calculation and CFRP material mechanics model is verified by the impact of aluminum flyers on CFRP materials.Through the simulation of carbon fiber reinforced phenolic resin material(C/PF)planar plate impact test,the characteristics of the material mechanics model proposed in this paper are quantitatively analyzed.Furthermore,we simulated the Sandia Z-pinch experiment which the Al target irradiated by X-ray and get the blow-off impulse.The comparison between the experiment and theoretical model with our simulation results verify the accuracy and reliability of TSHOCK3 D program for the dynamic response of X-ray irradiation.4.The dynamic response of CFRP materials under several typical blackbody X-rays in three-dimensional condition is simulated by TSHOCK3 D program and the blow-off momentum and thermal shock wave propagation law are analyzed.The calculation results indicate that anisotropic properties of CFRP materials have a great effect on thermal shock wave propagation.Comparing with the aluminum material,in the same condition CFRP can reduce the blow-off impulse and the peak pressure effectively.5.Regarding to the need of large-scale numerical calculation of the anti-radiation reinforcement research,a parallel computing design scheme combining data parallel and process parallel is proposed for TSHOCK3 D program.Parallel computing of programs is implemented on a personal computer using the MPI parallel library and this algorithm has an excellent scalability.The parallel program can compress the calculation time to about 20% of the serial calculation editon,and the acceleration efficiency is maintained at about 70%.