基于平稳小波变换的悬臂梁微小缺陷检测方法研究  

Small crack identification in cantilever beams by stationary wavelet transform

作　　者：欧芬兰 郭金泉[1] 钟剑锋[1] 钟舜聪[1,2] 

机构地区：[1]福州大学机械工程及自动化学院,福建福州350108 [2]福建省医疗器械和生物技术重点实验室,福建福州350000

出　　处：《机电工程》2015年第6期762-767,共6页Journal of Mechanical & Electrical Engineering

基　　金：国家自然科学基金资助项目(51005077);教育部高学校博士学科点科研基金资助项目(博导类;20133514110008);国家卫生和计划生育委员会科研基金资助项目(WKJ-FJ-27);福建省杰出青年基金滚动资助项目(2014J07007);福建省质量技术监督局科技项目资助项目(FJQI2013095;FJQI2012024);福建省高等学校学科带头人培养计划资助项目(闽教人〔2013〕71号);国家质检总局科技计划资助项目(2011QK216)

摘　　要：针对悬臂梁微小缺陷难以直接从模态振型进行有效识别的问题,提出了基于平稳小波变换的悬臂梁微小缺陷检测方法。通过利用有限元方法对悬臂梁进行建模和模态分析,得到了悬臂梁的模态参数。在此基础上,通过利用平稳小波变换对悬臂梁模态振型进行正交分解以得到平稳小波变换的近似系数(含模态振型的低频信号成份)和细节系数(含模态振型的高频信号成份)。最后,从平稳小波变换细节系数中提取了悬臂梁的微弱缺陷信息,实现了悬臂梁微小缺陷的有效定位和检测。从有限元模拟和平稳小波变换的结果可知,悬臂梁不同位置缺陷的前四阶细节系数都可以有效用于微小缺陷的定位。该方法具有较好的检测精度和可靠性,在结构缺陷萌生之初就可以有效识别缺陷的存在,避免结构灾难事故的发生,可推荐用于实际工程结构的检测。Aiming at the difficulty in effective determinations of the existence of the cracks/defects in cantilever beams with small cracks due to weak crack effects, a methodology was proposed for small crack identification in cantilever beams by using stationary wavelet transform （SWT）. Modal analysis of cantilever beams were modelled and analyzed by using finite element （FE） method. The obtained modal shapes of cantilever beams were orthogonally decomposed by using SWT into approximation coefficients （ which include the low-frequency components of modal shapes） and detail coefficients （ which include the high-frequency components of modal shapes）. Finally, the SWT detail coefficients were used to extract small defect features, therefore, small crack localization and identification in cantilever beams were realized. The FE and SWT results indicate that the detail coefficients for the first four modal shapes of damaged cantilever beams could be effectively used for the localization of small cracks. The SWT-based method has excellent detection precision and robustness. Small cracks in engineering structures could be identified avoiding the catastrophic failures, especially when the crack is initiated. Therefore, it could be recommended in real engineering applications.

关 键 词：振型 平稳小波变换 有限元分析 缺陷识别 

分 类 号：TH113.1[机械工程—机械设计及理论]