The Testing And Experimental Verification Of Three-Dimensional Split Hopkinson Pressure Bar Apparatus

To develop the high-speed tri-axial impact test equipment for testing the dynamic properties of materials under tri-axial impact and for verifying the relevant strength criterion and acquiring reliable materials parameters,this paper presents how to build three-dimensional SHPB apparatus based on the traditional SHPB experimental techniques and principles.Through finite element simulation and experimental verification,this paper studies the feasibility,stability and synchronization of this three-dimensional SHPB apparatus which had been set up by our research group.The main researches and conclusions in this paper are described as follow:(1)The detailed design philosophy of three dimensional SHPB is proposed and three-dimensional geometric model is set up.By the use of LS-NYDA,numerical simulation is conducted and the synchronization of incident waves and transmitted waves is analyzed with the force analysis of the specimen.(2)On the fabricated three-dimensional SHPB apparatus,PMMA is chose to be the specimen and the synchronization of incident waves and transmitted waves is verified.Through multiple repetitive testing,the repeatability of testing results and the stability of this apparatus is validated.(3)Two overall testing are conducted and through the comparison of testing results between this apparatus and traditional SHPB,the feasibility and reasonability of this device are studied.Moreover,environmental noise is analyzed to validate the reliability of testing results.Through numerical simulation and experiment,the main conclusions obtained are as follows:(1)By the use of single striking bar to un-coaxially strike three incident bars,uniform elastic wave can be produced in each incident bar.All of the incident waves are achieved in a state of synchronization and equal-amplitude.(2)Transformed heads are applied in this apparatus to achieve the smooth transition of different sections,and all of the transmitted waves are achieved in a state of synchronization and equal-amplitude.(3)It is verified that this apparatus could be used to generate equal-amplitude and tri-axial synchronized dynamic impact loads on the testing specimen.The wave features in each bar are evident and can be distinguished easily.(4)The stress wave measurement approach applied in this apparatus is applicable.Intact signal can be acquired in each bar with little error and minor environmental noises.In terms of the operability,this apparatus is stable and has favorable repeatability.