基于提高频率灵敏度的结构损伤统计识别方法

提出了一种基于反馈控制结构动力特性的损伤统计识别方法。该方法采用基于独立模态空间的反馈控制,有目的地配置闭环系统的极点,根据损伤前后闭环系统的特征值构造损伤指标。采用假设检验判断损伤是否发生,并剔除特征量中损伤程度的影响,采用统计模式识别方法识别损伤位置。Benchmark结构的数值算例表明,本文提出的损伤识别方法能够较显著地提高模态频率对刚度变化的灵敏度,准确有效地检测在噪声环境下结构小损伤是否发生以及识别损伤位置。

Statistical damage detection based on frequencies of sensitivity-enhanced structures

A statistical method using frequencies of structures under control is proposed for detecting small damages.In the study,feedback control based on independent modal space control is first used to assign the pole of the system under detection intentionally.Then the prescribed characteristic frequencies of the structure under control,which may be more sensitive to the damage,are obtained and further employed to constitute a sensitivity-enhanced damage indicator(SEDI).The principle of sensitivity-enhancing feedback control for stiffness damage detection of multi-degree-of-freedom systems is argued in theory.To tolerate measurement noise on modal frequencies,a hypothesis test involving t-test that utilizes the SEDI to constitute the statistical quantity is employed to estimate the existence of damage while a statistical pattern recognition method that uses the feature vectors consisting of SEDI is employed to locate damage.Based on perturbation theory the feature vectors are normalized in order to eliminate the effect of damage extent on damage localization.The proposed method is verified by examples including the damage detections of the IASC-ASCE benchmark structure with self-defining single damaged brace.Simulation results show that the proposed damage indicators are more sensitive to damage by using the frequencies of the structures under control and are capable of detecting and locating small damage of structures.