Expansion of real-time operating data from limited measurements to obtain full-field displacement data has been performed for structures in air. This approach has shown great success, and its main advantage is that the applied forces do not need to be identified. However, there are applications where structures may be immersed in water and the full-field real-time response may be needed for design and structural health assessments. This paper presents the results of a structure submersed in water to identify full-field response using only a handful of measured data. The same approach is used to extract the full-field displacements, and the results are compared to the actual full-field measured response. The advantage of this approach is that the force does not need to be identified and, most importantly, the damping and fluid–structure interaction does not need to be identified in order to perform the expansion. The results show excellent agreement with the measured data.

This paper is aimed at developing a computationally efficient approach to simulate the vertical dynamic behavior of vehicle–track coupled system. With the finite element method, the car body, bogies, and rail are modeled as Euler beams supported by springs and dashpots, which can investigate the influence of flexibility of the vehicle on structural dynamic response. By a variant of component-mode synthesis (CMS), the degrees-of-freedom (DOFs) within the substructures are condensed and the two substructures are coupled through nonlinear Hertzian theory. Although the system matrix is updated and factorized during the calculation, the total computational efficiency is significantly improved due to the much smaller size of the equations of motion and direct solution algorithm instead of iterative procedure. Compared with an existing model, the accuracy and efficiency of the method are investigated. Application of the model is shown by numerical example.