Study The Stress State Of Concrete-like Materials In SHPB Experiment Test

Concrete is one of the most important materials in engineering. Due to the lackof study on its dynamic strength, it is necesary to study the dynamic strength ofconcrete-like materials, especially in the field of infrastructure andconstructionprotection. This thesis briefly reviews the progress of the dynamic compressionstrengthof concrete-like materials, and the empirical formulaof dynamic increasefactor (DIF) have been discussed. It is noted that the dynamic loading may affect thestress stateof the specimen.Previous studies on the DIF is limited in one-dimensionstress state of specimens, which do not consider the case of conplex stress state.Theinfluence of the stress state in SHPB of specimen should be considered for thedeterminated of the DIF of concrete materials. The model number72in LS-Dyna(Mat concrete damage rel3, K&C model) has been used in SHPB simulaton,to obtainstress and strain states of the specimen. Using this model,SHPB specimens indifferent aspect ratios and different diameters with or without friction are simulated.Details are described as follows,(1) K&C model is used to simulate specimen of different aspect ratios anddifferent diameters. By changing the coefficient of friction of the bar specimencontact,stress state in the specimen is analyzed. The results show that the frictioncoefficient, concrete specimen diameter and aspect ratio have a greater influence onstress state of specimen at high strain-rate.(2) Damage coefficients in K&C model, i.e b1compressivedamagecoefficient,tensile failure coefficient b2, triaxial tensile damage coefficientparameters b3are analyzed in order to get the appropriate parameter values, providinga reference for future experimental research. The results show that the parameterb1plays great influence on stress-strain relationship at high strain-rate, while the othertwo parameters have negligible influence on dynamic stress-strain relationship.The conclusion of this study may guide the SHPBtestdesign and theinterpretation of experimental results.