层合梁横向冲击的动力学效应

Dynamic Effect of Laminated Beam Subjected to Transverse Impact

研究了十字叠层复合材料梁横向冲击响应的动力学效应，根据冲击实验曲线用动态有限元方法计算了惯性效应和应力波效应对位移和应力响应的影响。

A study on dynamic effect of three point bending beam made of laminated composite subjected totransverse impact have been carried out. Emphasis of this investigation is focused upon the inertia effectand stress wave effect on the impact response and stress distribution of the beam. Dynamic finite elementanalysis was conducted and the famous commercial program ABACUS was utilized. The impact loadingfunction of time recorded in the experimental study of the previous paper was used in the FEM analysis andthe resulted deflection response δ(t) of FEM was compared with that of experiment, The FEM δ(t) curveexhibits some difference from that of experiment, i. e. there is small high frequence oscillation wave superposing on the main δ(t) curve of FEM, whereas the recorded δ(t) curve is simply straight. This is because of ignorance of the mass of impact hammer in FEM calculations, but in the drop weight impact testthe beam specimen combining the hammer constitutes a vibration system. The period of the oscillation isproved to be the period of free vibration of the beam for the first vibration mode.The stress wave propagation was examined. At the early period of the loading process, the stress waslocalized in small area of the vicinity of impact point and the stress values in the upper layer of the beamwas larger than those in the lower layer. At the later stage of loading process stress distribUtion tends tobe the same as static bending. For studing the effect of loading rate, three loading cases were considered.When the maximum load was reached, the stress for the drop weight loading case is nearly the same asstatic loading. On the contrary, if the loading rate is enhanced by a factor of 25, the stress was smallerthan the former two cases for the same load level.