The Numerical Simulation Of Split Hopkinson Pressure Bar Experimental Technique

Split Hopkinson pressure bar(SHPB) is the basic technique that has been used to measure the dynamic mechanical property of materials.With the widen of SHPB experimental technique application area and with the improve of the request for experimental equipment and experimental accuracy ,to improve and optimize SHPB experimental technique is very important. Numerical simulation plays an important role in it.With the help of the software Ansys/Ls-dyna this article presents the three dimensional numerical simulation of SHPB, discussed the dependability of numerical simulation from the element selection, the Hourglass control, the minimum interval of time, the mesh divide, the contact control, and initial loading etc. Next, this article make a numerical analysis of several key problems about the split Hopkinson pressure bar experimental technique.1. Effects of the mesh divide on collision contact simulation. When mesh dividing , it is necessary to control element proportional relations between radial sizes and vertical sizes according to SHPB geometric model characteristics.2.The contact option between bullet and bar ,bar and specimen. Contact stiffness is an important factor in the simulation fidelity. Especially contact option between bar and specimen, Contact stiffness is very sensitive to the result of stress and strain in the contact interface3. To make it easier for us to study Effects of different wave form on the SHPB , the method, loding rectangle velocity wave form directly on one end of the press bar where come into collision with bullet, is practicable4. Effects of the the diameter, material Poisson ratio and variable cross-section of the press bar on the dispersion of wave .Come to the wave dispersion risetime , which the wave result of collision between different diameter- φ 14.5mm φ37mm φ100mm bullet, which length is 500mm ,and pressure bar, in different positions of the pressure bar.5.Effects of acoustical impedance proportion and different wave form on the specimen's stress and strain uniformity. Pull off a cycle that is from numerical simulation under a given mechanical properties of materials to properties reconfiguration of materials with the help of the numerical simulation result. Set up a standardization process about the application of numerical simulation to the split Hopkinson pressure bar experimental technique6. Effects of the diameter geometric size of pulse shaper and property parameter of material on the wave shape . The diameter of pulse shaper and Young modulus have great influence to the risetime, on the other hand, the thickness and Tang model have obvious influence to the wave curvature7.The specimen processing quality(for example The uneven degree of specimen) have great influence to the two dimensional effect of specimen. Because of defect on the specimen surface, stress concentration cause prematurely damage to the specimen...