Study Of Impact Response Of TiNi Phase Transformation End Clamped Beam

Phase transformation material has been widely used in engineering for its peculiar mechanical properties. The study of mechanical property is relatively mature, but it is very short of the study of the mechanical property of the phase transformation structures, especially the response under impact loading. The study of the impact characteristics of phase transition structure is significant in both application and academic. In this paper, the dynamic response of end-clamped phase transformation beam is systematically investigated experimentally and numerically, and some interesting phenomena and regularity has been found.The dynamic response of the PE end-clamped beam under large mass low speed impact loading is investigated by experimental and numerical simulation methods. The dynamic response of phase transform clamped beam and the effect of the phase transform on the deformational mechanism is illustrated in detail by the analysis of evolutional regulation of phase transformation hinge, moment and axial force in the dynamic response. The early response of end-clamped beam is mainly the propagation of elastic flexural wave. The dynamic response will turn to structural response after the 3-5 reciprocate propagation of elastic flexural wave in the beam. The elastic flexural wave is gradually turn to phase transform flexural wave under the impact loading, which will lead to the formation of phase transform hinge in the mid and end of the beam. The strain and energy deposition will be localization due to the formation of phase transform hinge, which further lead to the formation of two bar hinge structure. The neutral layer of the beam will move. The deformation of the beam will turn to rotation of the phase transformation hinge and the tensional deformation of bar, meanwhile axial force will be the main factor. This process is as follows:The propagation of elastic flexural wave; elastic structural response; phase transform in location; the formation and evolution of phase transform hinge; phase transform hinge movement; the formation of bar hinged structure. The dynamic response will be localization for localized phase transform. The formation of phase transform hinge caused the beam to rotate around the hinge, which lead to the moment out of hinge area decrease rapidly and the propagation of high frequent flexural wave depressed obviously. As the material in the phase transformation hinge changed into the martinsite phase, the phase transform hinge will be separated and move separately. The phase transition disappeared under unloading and the beam turn to the initial condition. The result shows that the phase transformation hinge has greatly different characters compared with traditional ideal elastic-plasticThe experiment was conducted on the PE beam under the small mass high speed condition, using revised split Hopkinson pressure bar (SHPB) apparatus. Meanwhile, the asymmetrical impact experiment was conducted. The result shows that:the flexural wave motion response time is about lms. The flexural wave response characteristic under the high velocity impact is that the amplitude of flexural wave is of high value. The phase transition will be generated in the beam as the reflected wave superimposed with the incident flexural wave. However, it is unstable and will disappear because of the low phase transition percent. The phase transition flexural wave is formed during the dynamic structural process. The amplitude value of the flexural wave will increase as the impact velocity increasing, which will lead to distribution of the martensite is different. The higher frequency and lower value wave will be generated and propagating in the hinged beam under small mass high speed loading, which will lead to the phase transformation hinge generated time increase. Two phase transformation zone will be generated in the mid and the end in the shorter part of the beam under the asymmetrical impact loading and there is a elastic zone between the mid and the end. For the longer part of the beam there will be a phase transformation zone occur between the mid and the end. The result shows different character of dynamic response compared with symmetrical impact. Because of temperature effect, the phase transition areas increase and there is no two bar hinge structure formed. The phase transformation will lead to the temperature increase and further lead to the phase transformation harder, at the same time the phase transformation will made the material soft. The synthesis of the two effects should be studied in the next step.The dynamic response under different mass ratio of impact object and beam is studied, at the same time the dynamic response under different velocity is investigated by numerical simulation. The results show that, the impact velocity has more great effect on the wave motion process than the impact object mass. The kinetic energy of the impact object has great effect on the dynamic structural response. The axial force is the natural characteristic of the end-clamped beam under the dynamic impact, which makes energy store as tensional deformation energy.The dynamic response of infinity beam and end-clamped beam under different amplitude value step load were investigated by numerical method. The analytical solution of the elastic flexural wave of the end-clamped beam and the hinged beam under step loading were obtained by modal superposition method. The comparison was made between the analytical solution and the numerical solution. The comparison result shows there are great inaccuracy in 0.01ms, which was lead by the lack of the mode and the higher frequency are invoked in the 0.01ms. There is well agreement as time increase and the effective of the numerical simulation is tested. The effect of shear and rotary inertia was discussed and the result shows that the effect can be ignored for the beam. The dynamic response of the infinite beam was studied by a beam which length is two meters. The results of moment and martensite distribution were obtained. The effect of phase transformation on the dynamic response was studied by these results, and the results shows the phase transformation can depress the flexural wave propagating in the beam. The phase transformation will occur in the wave motion period under high amplitude value load and will occur in the structural response period under low amplitude value load. The inertia force has great effect on the dynamic response, and the final dynamic response is the vibration around the equilibrium position.