基于时变刚度模型的悬臂梁损伤识别研究

摘要

考虑呼吸裂纹引起的损伤结构的非线性效应，提出裂纹悬臂梁的指数衰减时变刚度模型，分析结构瞬时频率与损伤位置和损伤程度的关系；利用中心差分法和Teager能量算子求解自由振动响应的瞬时频率；基于瞬时频率对结构的损伤识别进行探讨，建立损伤指标，识别结构的损伤程度；考虑噪声对损伤指标的影响。研究结果表明：结构瞬时频率是损伤位置和损伤程度的二维函数，瞬时频率的波内调制验证了结构的非线性，表明时变刚度模型的合理性，损伤指标具有一定的抗噪性。%A time-varying exponential damped stiffness model was proposed by considering non-linear effect of breathing crack to damaged structure.Relationships between the structural instantaneous frequencies (IFs)and damage location as well as degree were analyzed.IFs of the free vibration displacements were obtained by using central difference and Teager energy operator (TEO)and damage detection based on IFs was studied.The dam-age indexes were established and the damage degree was identified.Meanwhile,the noise effect was considered. The results show that structural IFs are two-dimensional function of damage location and degree and the intra-wave phenomenon of IFs verifies the non-linearity of damaged structure,which shows the rationality of the time-varying stiffness model and indicates the anti-noise properties of damage indexes.