Error Analysis of Interface Friction Effect of Metal Material in Split Hopkinson Pressure Bar Test
Stress-strain curves of 38CrMoAl high-strength steel were reconstructed by split Hopkinson pressure bar(SHPB)test and finite element simulation.The effects of end-face friction coefficient(0,0.1,0.2,0.3,0.4,0.5),bullet incident velocity(20,30,40 m·s-1),sample length-diameter ratio(0.25,0.50,1.00)and sample shape(cylinder,cube)on the test error of peak stress and peak strain induced by end-face friction effect were studied.The results show that the test errors of peak stress and peak strain increased with the increase of end-face friction coefficient,and decreased with the increase of length-diameter ratio.With the same section area,the test error difference between cylindrical and cube samples was less than 2％.When the end-face friction coefficient was large,the test error could not be effectively reduced by controlling the bullet incident velocity.If the end-face friction coefficient of the sample was reduced below 0.1,or the length-diameter ratio of the sample was larger than 1.00,the end-face friction effect error could be effectively reduced.The stress concentration occurred in the middle and the edge of the end-face of the sample.With the increase of the length-diameter ratio of the sample,the proportion of the stress concentration in the total length of the sample decreased,and the influence of the end face friction effect decreased.
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