This paper presented the process of implementing and developing a novel damage detection approach on beam like-structure using modal parameters. In Theoretical Modal Testing (TMT), the mode shapes, mode shape curvatures and natural frequencies were extracted by formulating differential equations of motion of un-cracked and cracked beams. In Experimental Modal Testing (EMT), the transient excitation method of modal testing is performed by using an impact hammer test. EMT involves an extraction of natural frequencies through frequency response functions at various surface cracks on the beam in a virtual instrumentation environment. Cantilever beams of Aluminum 6061 is considered for analysis with crack position at the interval of 50 mm from fixed end to free end at varying crack depths 20%, 40% and 60% of the beam total depth. The modal data from experimental modal testing was validated with theoretical modal testing data. It was observed that there was a minor change in lower modes; major change in natural frequencies for higher modes with the variation of damage location/depths. To overcome the difficulty in crack detection of structures based on mode shapes and frequencies individually, both the parameters mentioned are collectively used in this work as Frequency-Modeshape Based Damage Detection Technique (FMBDD) to evaluate the crack location as well as crack depth easily and accurately.

本文介绍了使用模态参数对梁形结构实施和开发新型损伤检测方法的过程。在理论模态测试（TMT）中，通过公式化未破裂和破裂的梁的运动微分方程，提取了振型，振型曲率和固有频率。在实验模态测试（EMT）中，模态测试的瞬态激励方法是通过使用冲击锤测试来执行的。在虚拟仪器环境中，EMT涉及通过频率响应函数在梁上各种表面裂纹处提取固有频率。考虑使用铝6061悬臂梁进行分析，其裂纹位置从固定端到自由端的间隔为50 mm，且裂纹深度变化为梁总深度的20％，40％和60％。来自实验模态测试的模态数据已用理论模态测试数据进行了验证。观察到较低模式的变化很小。对于更高模式，固有频率的主要变化随损坏位置/深度的变化而变化。为了克服分别基于模式形状和频率进行结构裂缝检测的困难，在本文中将上述两个参数共同用作基于频率-模式形状的损伤检测技术（FMBDD），以轻松评估裂缝位置和裂缝深度，并准确。