基于模态柔度曲率的损伤检测方法

由于模态柔度对结构损伤的高灵敏性,各种基于模态柔度的检测指标在结构无损探伤NDE(Nondestructive Damage Evaluation)中应用较多,如模态柔度差、模态柔度改变率和均匀荷载面曲率差等。这些指标经应用验证都具有一定的有效性。在此基础上,采用模态柔度曲率的改变构建一种新的指标,称为模态柔度曲率差(MFC)。尽管均匀荷载面曲率差也采用曲率,但不同的是它先将模态柔度矩阵按行加起来,再求损伤前后的曲率差。而提出的模态柔度曲率差则按列计算损伤前后模态柔度矩阵的曲率差,然后挑选每列里面最大的值作为指标。采用一个简支梁和一个四跨连续梁为算例,考虑各种损伤情况,将该指标与模态柔度差、模态柔度改变率和均匀荷载面曲率差、以及振型曲率改变率等指标进行了比较,证明了模态柔度曲率差检测损伤的有效性和优越性。

NONDESTRUCTIVE DAMAGE EVALUATION INDICATOR BASED ON MODAL FLEXIBILITY CURVATURE

Due to the high sensitivity of the change in modal flexibility to structural damage, quite a few nondestructive damage evaluation indicators based on modal flexibility have been put forward. These indicators, such as the change in modal flexibility, modal flexibility index and the change in uniform load surface curvature, were used in some cases and proved to be valid to some extent. In this paper, a new indicator is constructed. Rather than using the change in modal flexibility, the change in curvature of modal flexibility is adopted and called the modal flexibility curvature (MFC). Although the change in uniform load surface curvature also uses curvature, it is different from MFC since it adds up the modal flexibility matrix rowwise and then calculates the change of curvature, while MFC computes the change of curvature columnwise in the modal flexibility matrix and chooses the maximum in each column. Two simulations, a simple beam and a four-span continuous beam, are utilized to verify the new indicator. Compared to the aforementioned indicators and modal curvature index, MFC is proved to be valid and efficient in various cases, and superior to the competitors.