Research On Impact Resistance Of Composite Autobody Panel Based On Shape Memory Alloy

Composite autobody panels are sensitive to impact and are prone to damage such as delamination,matrix cracking and fiber breakage,resulting in reduced strength.Superelastic nickel-titanium shape memory alloy(Ni-Ti SMA)has hysteretic damping,impact resistance,superelasticity and other characteristics.In the loading process,when the strain reaches a certain level,the phenomenon of phase change,lattice shear,etc.will occur,thereby absorbing the impact energy.During the unloading process,reverse phase transformation will occur.Part of the internal energy is converted into heat loss,and thus part of the impact energy is dissipated,and without residual strain.The above characteristics of Ni-Ti SMA provide new ideas for improving the low-speed impact resistance of composite materials.In this paper,the super-elastic Ni-Ti SMA wires are laid as an additional reinforcing fiber in the glass fiber composite plate.The impact response of the composite plate is studied through the combination of simulation and experiment.The main contents are as follows:(1)The quasi-static tensile experiments of super-elastic Ni-Ti SMA wires were performed to obtain the basic mechanical parameters of Ni-Ti SMA wires,which provide material properties for the finite element model of Ni-Ti SMA wires.According to the stress-strain curve of Ni-Ti SMA wires,a piecewise linear model was constructed to derive the energy density and energy density formulas,which provides a theoretical basis for the calculation of Ni-Ti SMA energy density.The effects of strain amplitude,strain rate,and cyclic loading-unloading on the energy density of Ni-Ti SMA filaments were analyzed.The quasi-static tensile finite element simulation of Ni-Ti SMA wires was performed.The energy density and energy density were compared with the experimental results.The error was less than 10%.The validity of the simulation results was verified.(2)Using the contact molding method,the glass fiber composite material plate was prepared,and the material modulus,shear modulus,Poisson ratio and other material parameters of the composite material plate were measured by tensile test,shear test,and electrical test.Provide material properties for the creation of finite models of composite plates in ANSYS/LS-DYNA.(3)Glass fiber composite plates with Ni-Ti SMA wires and without Ni-Ti SMA wires were prepared,and impact simulation was performed on the two composite plates to analyze the impact response of the Ni-Ti SMA wires to the composite plate(center deflection of the plate and its peak,impact force and its peak,absorption energy,etc.The results show that after embedding Ni-Ti SMA wire,the hysteresis loop effect of Ni-Ti SMA wires causes some of the impact energy to dissipate,and the remaining energy of the composite plate is increased.It is verified that Ni-Ti SMA wires participate in the impact energy absorption and Dissipation,composite material plate peak deflection,impact time,impact response improved.(4)The influence of laying density and laying position of Ni-Ti SMA wires on the impact response of the composite plate was simulated.The results show that the stiffness of the composite plate increases with the increase of laying density and the position of the layup,and the absorption of Ni-Ti SMA wires increases.As the impact energy increases,the impact energy,deflection peak,and impact time of composite plates are reduced.(5)Based on the Vic-3D-v7 non-contact full-field strain measurement system and the DH5922N dynamic signal test and analysis system,the impact test bed for composite material plates was designed and constructed,and the impact test was performed on composite plates containing superelastic Ni-Ti SMA wires.The experiment and simulation results under the same impact condition show that the simulation is in good agreement with the experiment and the validity of the finite element simulation conclusion is verified.(6)Impact tests were performed on composite plates containing different metal wires.Studies have shown that,compared with ordinary wire,Ni-Ti SMA wires can more effectively improve the ability of composite materials to withstand the impact load,the peak deflection,impact time,residual deflection is reduced,inhibit the expansion of the material damage.(7)The comparative analysis of the impact responses of composite plates with Ni-Ti SMA wires and without Ni-Ti SMA wires.The experimental results show that the Ni-Ti SMA wires reduce the peak deflection of the composite plate by 37%and the impact time is reduced.For 2.92ms,the residual deflection is reduced to Omm,and the energy returned by the composite material to the punch increases by 3.18J,which reduces the energy used for damage and effectively reduces the impact damage of the composite material.(8)Composite plates with Ni-Ti SMA wires and without Ni-Ti SMA wires were subjected to two impacts respectively,and the response curves of the composite plate containing Ni-Ti SMA wires showed no significant change compared with the two impact responses.The shock curve of the composite plate without Ni-Ti SMA wires oscillates violently,the peak deflection increases further,and serious damage occurs,which proves that the Ni-Ti SMA wires improve the impact resistance of the composite plate.(9)The impact response analysis of composite plates containing Ni-Ti SMA wires with different diameters shows that with the increase of the diameter of Ni-Ti SMA wires,the peak value of the impact force can be increased,the peak deflection and impact time are reduced,and the diameter is reduced.When the thickness exceeds 0.4 mm,the effect of reducing damage is stabilized.