Temperature effect extraction based on variational mode decomposition

Change of the damage characteristic parameter caused by local damage of the structure is often masked by the normal fluctuation caused by the ambient temperature, which leads to the misjudgment of the structural safety state. It is necessary to separate the temperature effect from the measured response. However, the linear response separation method cannot handle the nonlinear problems of some complex structures; the common nonlinear methods have some shortcomings need to be solved, such as poor adaptability, unavoidable endpoint effects, and so on. Therefore, a separation method of temperature effect based on variational mode decomposition (VMD) is proposed. According to the multi-time scale characteristic of the measured response, the basic principle of VMD is used to correspond each response component with the intrinsic mode function; and then, based on the estimated bandwidth of the intrinsic mode function, the response separation problem is equivalent to the constrained variational optimization problem; based on the nonlinear alternating direction method of multipliers, the temperature effect is extracted by solving the optimal solution.