A non-iterative partitioned computational method with the energy conservation property for time-variant dynamic systems

A non-iterative partitioned computational method with the energy conservation property is proposed in this study for calculating a large class of time-variant dynamic systems comprising multiple subsystems. The velocity continuity conditions are first assumed in all interfaces of the partitioned subsystems to resolve the interface link forces. The Newmark integration scheme is subsequently employed to independently calculate the responses of each system based on the obtained link forces. The proposed method is thus divided into two computational modules: multi-partitioned structural analyzers and an interface solver, providing a modular solution for time-variant systems. The proposed method resolves the long-standing problem of iterative computation required in partitioned time-variant systems. More specifically, the proposed method eliminates the need for time-variant matrix formation and the utilization of complex iterative procedures in partitioned computations, which significantly improves computational efficiency. The derivation process and theoretical demonstration of the proposed method are thoroughly presented through a representative example, i.e., a vehicle-rail-sleeper-ballast time-variant system. The proposed method's accuracy, energy conservation property, and efficiency are systematically demonstrated in comparison with the results of the global model, highlighting its superior performance. A more general example provided in Appendix C demonstrates that the proposed method is not confined to the analysis of vehicle-rail-sleeper-ballast systems but applies to other structural dynamic systems

Decentralized bayesian substructuring damage detection approach using nonstationary response measurements

A Bayesian substructuring identification technique allowing for monitoring of some critical substructures is proposed in this study by using nonstationary response measurements only. Instead of optimizing all the unknown parameters simultaneously, a coupled iterative scheme involving the optimization of the parameters in groups is also employed so as to reduce the dimension of the numerical optimization problem involved. To exploit the decentralized data processing ability of wireless sensor networks, a distributed computing strategy is proposed for the proposed Bayesian substructuring algorithm. A 20-storey shear building model subjected to nonstationary excitation is used to verify the proposed method. © 2013 Taylor & Francis Group, London

Defect Detection and Location in Switch Rails by Acoustic Emission and Lamb Wave Analysis: A Feasibility Study

An acoustic emission (AE) based approach is proposed in this study to identify and locate newly initiated defects or the propagation of existing defects in railroad switch rails. Defect-induced AE signals are identified through frequency analysis, as frequencies of these signals are much higher than those induced by structural vibration. Continuous wavelet transform (CWT) is employed to analyze the Lamb wave dispersion of the detected signal, so that two characteristic points can be selected on the CWT contour map to locate the defect. Using this approach, defects in a damaged switch rail can be located using a single sensor