Prediction of response variability in uncertain point connected structures using component mode synthesis and characteristic constraint modes

Finite element analysis is frequently used in conjunction with Monte Carlo simulations (MCS) to predict the variability in the vibration response of assembled structures with uncertainties in the joint properties. Nonetheless this is usually computationally expensive, especially for large scale models. In this paper, component mode synthesis (CMS) is applied to point connected structures in order to reduce the size of the model. In addition, in order to spatially locate the connections anywhere in the model multipoint constraints are used. However, if the number of degrees of freedom (DOFs) involved in the connection is large, then the CMS size reduction is less effective. Characteristic constraint modes can then be used to reduce the number of interface DOFs. The application of the technique is demonstrated on a model of two simply supported plates with five point connections. A MCS is used to evaluate the variability in the vibration response of this system due to uncertainty in the location of the point connections. Results show that this procedure not only reduces the computational time by approximately 90%, but also maintains good accuracy in the estimation of responses when compared to the standard modal solution