Identification of structural parameters using consistent mass transfer matrix

Abstract

The stiffness parameters of structural members are identified by a novel inverse scheme based on consistent mass transfer matrix (TM), and the results are experimentally verified. The parameters are identified from the measurement of the state vector at a starting point, and displacements at few other locations. A new consistent mass-based TM is derived from the dynamic stiffness matrix of a beam element. The state vector at a location is the sum of the internal and external contributions of displacements, forces and moments at that point. When these are multiplied with the TM we obtain the state vector at the adjacent node. The identification algorithm proposed in this inverse problem involves predicting the displacements at certain locations using the TM, and comparing them with the measured displacements at those locations. The mean square deviations between the measured and predicted responses at all locations are minimized using an optimization algorithm, and the optimization variables are the unknown stiffness parameters in the TM. A non-classical heuristic particle swarm optimization algorithm (PSO) is used, since it is especially suited for global search. This TM method is particularly suited for local identification in large structures. Numerical simulations are carried out on two examples such as a cantilever, and a substructure of a nine-member frame structure. The method is also experimentally validated on a cantilever and substructure of a fixed beam. The speed and accuracy of the method are compared with existing structural identification methods, and advantages on the above are observed.