桁架结构疲劳监测的应变响应估计方法研究

传感节点数据的高效利用是结构健康监测领域的热点研究问题。由于高维护成本和恶劣服役条件，结构疲劳监测系统往往测点有限，难以覆盖易损区域。该文针对两种应变响应估计方法:增广卡尔曼滤波方法和应变传递率矩阵方法进行研究探讨，并通过典型桁架结构的数值案例和模型实验分析两种方法的影响因素和疲劳监测的适用性。结果表明:两种方法无需已知荷载信息或进行物理参数识别，能够在仅有某一子结构可测，以及一定测量噪声和建模误差干扰的条件下有效估计低频带的强迫振动响应。其中，应变传递率矩阵方法可在结构阻尼和质量未建模的情况下，利用简单的模型先验信息精确估计应变响应，该方法计算简便，因而更加适合现场的疲劳在线监测。

RESEARCH ON A STRAIN RESPONSE ESTIMATION METHOD FOR TRUSS STRUCTURE FATIGUE MONITORING

Making full use of the information from sensing nodes efficiently is an important and hot research field in structural health monitoring. Due to high maintenance costs and harsh service conditions, structural fatigue monitoring systems tend to have limited measuring points and be difficult to cover vulnerable areas. In this paper, two types of strain response estimation methods, that is, the augmented Kalman filtering and the strain transmissibility matrix are introduced and discussed. Numerical examples and demonstration tests of typical truss structures were conducted to investigate the influencing factors and the practicality of the two methods for fatigue monitoring. The results show that the two methods can effectively estimate the forced vibration responses at a low frequency band under the condition that only one substructure is measurable with a certain extent of measurement noise and modeling error, without having to know the load information or identify the physical parameters. It is noted that the strain transmissibility matrix method can accurately estimate the strain response with simple prior information of the model and fast computation capability without considering the structural damping and mass. Therefore, the strain transmissibility matrix method is more suitable for on-line fatigue monitoring.