复合材料吸能圆管在半圆凹槽触发机制下的斜向压溃失效行为

Oblique crushing failure behaviors of composite energy-absorbing circular tube under the semi-circular cavity triggering mechanism

有效的触发机制能诱导并改善复合材料吸能结构的轴向渐进压溃行为,但仍无法解决汽车吸能结构在斜向冲击载荷下的失稳问题。为了提出新的设计来改善失稳行为,对复合材料吸能圆管在半圆凹槽触发机制下的斜向压溃行为和失效机制进行研究。建立引入半圆凹槽触发机制的圆管有限元模型,采用界面和层内非线性损伤演化模型来模拟其真实的压溃失效模式。通过对比模拟和实验对应的轴向压溃载荷、吸能和失效模式来验证圆管的准静态压溃模型。进而,预测斜向压溃角度(10°~50°)对圆管在半圆凹槽触发机制下压溃行为的影响,并详细揭示其轴向和斜向压溃失效机制及其区别。结果表明,压溃载荷、吸能及失效面积随角度增大而明显减小,不稳定的压溃过程使材料失效耗能不充分。圆管在轴向压溃下表现为渐进破坏,而在斜向压溃下以“渐进破坏”向“失稳破坏”过渡为特征,导致斜向压溃载荷与吸能曲线均存在一个过渡。本研究加深了对圆管在外部触发机制下斜向压溃失效机制的理解,为改善斜向压溃失稳行为提供了一定的设计依据。

An effective triggering mechanism can induce and improve the axial progressive crushing behaviors,but the instability problem of automotive energy-absorbing structure under the oblique crushing load has not been solved.To propose new designs to improve the instability behaviors,the oblique crushing behaviors and failure mechanisms of composite energy-absorbing circular tube under the semi-circular cavity triggering mechanism were studied.The finite element model of circular tube with semi-circular cavity triggering mechanism was established,and the interface and intralaminar nonlinear damage evolution model was adopted to simulate its actual crushing failure modes.The axial crushing load,energy-absorption and failure modes corresponding to simulation and experiment were compared to validate the crushing model of circular tube.Further,the effect of oblique crushing angle on the crushing behaviors of circular tube under the semi-circular cavity triggering mechanism was predicted,and both the axial and oblique crushing failure mechanisms and their differences were revealed in detail.Results show that the crushing load,energy-absorption and failure areas obviously decrease with the increasing the angle,and the failure energy-dissipation of material is inadequate due to unstable crushing process.The circular tube under the axial crushing exhibits progressive failure,but is featured by a transition from progressive failure to instable failure for the oblique crushing,leading to a transition occurring in oblique crushing load and energy-absorption curves.This study deepens an understanding for oblique crushing failure mechanisms of circular tube under an external triggering mechanism,providing some design bases for improving instability behaviors of oblique crushing.