The Development And Testing Research Of Impact Tensile Testing Apparatus For Low Impedance Material

With the development of science and technology and people’s growing emphasis on engineering guard safety,Low impedance material is widely used in the field of aerospace,architecture,car crash absorbing and many other safe guard engineering,such as PMMA and foams.So it is very important to study the dynamic mechanical properties of low impedance material.To modify a Effective testing device is a leading issue.Due to the limitations of experimental devices and testing techniques,the currency testing device have different degrees of impairment.Semiconductor strain test technology and incident pulse shaping technique were adopted to make an aluminum split Hopkinson Tensile bar apparatus for low impedance material.The compact tension specimens were tested and the dynamic fracture toughness of PMMA was calculated.The main contents of this paper are as follows:1.The current research dynamic test method were briefly introduced in this paper.then,the current research on the dynamic experimental device for low impedance material were briefly introduced as well.And the research of wave shaping method for the Hopkinson bar device by domestic and foreign scholars has been summarized,an overview research of wave shaping problem and dynamic experimental device for low impedance material has been done.2.The shaping feature of metal rod for Hopkinson tension bar apparatus was studied with the different size.With the method we can get the get the ideal amplitude and wavelength of incident wave.The effects of different materials and different thickness gaskets on the incident waveform has been discussed as well.3.In the LSHTB experiment,In order to reduce the influence of connecting sleeve on incident wave of SHTB.Optimal design of connecting sleeve’s geometry dimension has been dong with numerical simulation method,the influence of several important factors such as the rise time,duration time,fall time and the pulse amplitude to compare the before and after wave form were studied through the method of control variables with 4 kinds of length and 5 kinds of diameter.The simulation results has been compared with the experimental results as well.4.Semiconductor strain test technology and incident pulse shaping technique were adopted to make an aluminum split Hopkinson Tensile bar apparatus suitable for low impedance materials.The compact tension specimens were tested and the dynamic fracture toughness of PMMA was calculated.Simulation has been done on the dynamic fracture with the finite element method fpr calculating the dynamic fracture toughness value verifying the accuracy of the simulation through comparing test results.