Finite Element Simulation for Design Verification of a Small Size Split Hopkinson Pressure Bar

Split Hopkinson Pressure Bar is an apparatus that is used to study materials behavior under high speed deformation, where strain rate is very high. Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities or research labs. In this work, the authors designed a small size split Hopkinson pressure bar. The objectives of this project are 1) to design a well-structured Hopkinson bar by means of solid mechanics fundamentals 2) to implement finite element simulation to verify the design. The designed Split Hopkinson bar consists of two metallic bars with a specimen placing in between, a striker assembly, an air compressor, instrumentation and a data acquisition system. The solid model of the apparatus is built using CAD software SolidWorks. The design is validated by extensive finite element simulation using ABAQUS. A working prototype is physically built and tested. High speed deformation experiments are developed using the prototype fabricated. The experiments are conducted as an impact is made by the striker on one of the bars, which generates stress wave through the specimen and the other bar. During the experiments, strain in specimen is determined by measuring strains on the bars using strain gauges mounted on the bars. Preliminary tests demonstrate that the performance of the apparatus is as predicted by the FEM simulation. This work is supported by an NSF’s CMMI (Civil, Mechanical and Manufacturing Innovation) program.