Nonlinearity Identification of a Model Structure Equipped with SMA Wires Using Vibration Measurements

Damage initiation and development in engineering structures especially under earthquakes and strong dynamic loadings are typical nonlinear processes. The development of efficient and reliable identification approaches suitable for nonlinear systems is crucial for creditable damage initiation detection and severity identification of engineering structures. Even considerable attention has been paid to the development of vibration-based identification approaches, the identification theory of nonlinearity is far less established than that for linear systems. In this paper, a nonlinearity identification approach was developed and employed to identify the nonlinear behavior of a frame model structure equipped with shape memory alloy (SMA) wire which is a typical nonlinear material using acceleration response and excitation measurement time series. The performance of the proposed methodology was verified with dynamic test measurements. In the dynamic tests, SMA wire was introduced to the model to mimic the nonlinearity. Using the excitation force and acceleration measurement of the model structure, the restoring force provided by the SMA wire was identified. No any information about the system's mass should be known. Results show that the proposed data-based approach is convenient and efficient for nonlinear behavior identification of engineering structures.