夹心杆系统中一维弹塑性波演化精细分析(Ⅱ):弹塑性交界面与平台段反射衰减OA北大核心CSTPCD

Compared to the reflection and transmission analysis process during the incident wave loading phase,the incident wave plateau phase lasts longer,and the elastic-plastic propagation and evolution behavior are much more complex.The effects of elastic-plastic wave interactions within the specimen during this phase are very pronounced.Using the elastic-plastic incremental wave theory,combined with numerical simulation,the calculations of elastic-plastic wave's interactions inside the specimens under rectangular incident wave action and its elastic-plastic transmission and reflection behavior at the two interfaces are carried out.The attenuation characteristics of the reflected waves in the sandwich rod system are investigated.The results show that under strong incident wave action,the specimen internally forms a curve-shaped elastic-plastic interface due to the interactions of elastic-plastic waves.This causes the transmission end to reach the yield state significantly earlier.This elastic-plastic interface propagates towards the reflection end at a speed greater than the elastic sound speed.The attenuation of the reflected wave during the plastic phase is the sum of the increase in generalized wave impedance due to the increase in the specimen's cross-sectional area and the increase in the number of back-and-forth plastic waves caused by compression.Calculations also show that although the change of the specimen density significantly affects its wave speed and wave impedance,the sum of the attenuations caused by these two factors is close to zero.Hence,the effect of density changes on the transmission and reflection wave plateau phase can be ignored.An increase in the plastic modulus causes the reflection wave plateau to attenuate faster,but the effect of the specimen's diameter is not monotonous.When it increases from 4 mm to 10 mm,the reflection wave attenuation speed increases,but when it further increases to 12 mm,the attenuation amount decreases.This study has certain reference value for in-depth analysis of split Hopkinson pressure bar test for the transmission waveforms as well as for the detailed test design and data processing.