A semi-convex function for both constant and time-varying moving force identification. (1st January 2021)

• Record Type: Journal Article
• Authors: Liu, Huanlin; Luo, Ziwei; Yu, Ling
• Is Part Of: Mechanical systems and signal processing. Volume 146(2021)
• Publication Date: 2021-01-01
• Subjects: Moving force identification (MFI) -- Alternating iterative method (AIM) -- Semi-convex function -- Regularization technique; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2020.107062
• Languages: English
• ISSNs: 0888-3270

Abstract

Highlights: Inspired by the AIM, a semi-convex function is defined for effective MFI. Both constant and time-varying force components of moving forces are identified well. Solution ranges in MFI restricted by the semi-convex function are reasonable. Characteristics of identified results accords with the given prior knowledge. Abstract: In recent years, many moving force identification (MFI) methods have been proposed to monitor moving forces indirectly from structural responses. However, the prior knowledge about moving forces has not been reasonably considered in the existing methods, so the identified moving forces are not accurate enough. To improve the accuracy of MFI results, a novel MFI method is proposed based on a semi-convex function in this study. Firstly, a model of a simply-supported beam subjected to moving forces is taken as an example to establish the relationship between moving forces and structural responses. Then, the prior knowledge that time-varying force component of a moving force usually fluctuates around its static weight in the time domain is adopted. Thus, the moving force is decomposed into constant and time-varying force components. The constant force component is unchanged over time and the time-varying force component is changed over time. Based on this prior knowledge, a semi-convex function is defined for MFI, which is inspired by an alternating iterative method (AIM) and regularization techniques. As a result, the semi-convex function is solved by the AIM, so the constant and time-varying force components can be respectively obtained through iterations, and the moving forces are identified from structural responses. Finally, to evaluate the effectiveness of the proposed method, both numerical simulations and experimental verifications are carried out. The identified results show that the proposed method can further improve the MFI results by comparing with the L 2 regularization and the moving average Tikhonov regularization. The characteristics of the identified moving forces are consistent with that described in the given prior knowledge. Moreover, the proposed method can provide a good ability to estimate the total weight of the model car.