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In this study, the governing equations of a rotating cantilever pipe conveying fluid are derived and the longitudinal and lateral induced vibrations are controlled. The pipe considered as an Euler Bernoulli beam with tip mass which piezoelectric layers attached both side of it as sensors and actuators. The follower force due to the fluid discharge causes both conservative and non-conservative work. For mathematical modeling, the Lagrange-Rayleigh-Ritz technique is utilized. An adaptive-robust control scheme is applied to suppress the vibration of the pipe. The adaptive-robust control method is robust against parameter uncertainties and disturbances. Finally, the system is simulated and the effects of varying parameters are studied. The simulation results show the excellent performance of the controller.

A stable technique based on the finite element method for inverse analysis of coupled nonlinear thermo-elastic problems is presented. Not only the time-domain is divided into small intervals, but also the space-domain is divided into several sub-domains. The inverse problem is solved in each sub-domain subsequently. For the inverse analysis in each sub-domain, the unknown boundary conditions are found by using an optimization method and also by employing the information obtained in the previous sub-domain. The method is sufficiently stable to be used for inverse analysis of a thermo-elastic problem under a thermal shock. Three numerical examples are provided to demonstrate the efficiency of the proposed method. The effects of the number of sub-domains are investigated in the examples.

Many problems, involving finite deformation, necessitate an accurate treatment of sliding interface boundaries and impact conditions. Examples of this are the accidental impact of radioactive waste transportation packages, crashworthiness, fluid-structure interaction and various manufacturing processes including metal forming and cutting. In terms of general use and applicability, large scale nonlinear simulations involving arbitrary contact continues to pose a number of challenging issues. Faster computing processors and parallel processing strategies have helped to mitigate the impact of some of these issues on modelling. However, there is room for overall improvement in accuracy, efficiency and user-friendliness of contact algorithms used in the modelling of multiple body impact/contact, eroding surfaces where new free contact surfaces are created, large interface motions of initially unconnected surfaces and post-buckling behaviour of structures where surfaces fold onto themselves. For example, the benefits of using a faster processor with an iterative solver on an elliptic class of problem could be quickly neutralized if the number of iterations rise due to inaccuracies in the contact algorithm. In this paper, salient features of state-of-the-art general three-dimensional contact algorithms for use in finite element software based on explicit and/or iterative solution techniques are reviewed and some of the more complex modelling issues faced by users of such algorithms are addressed.

A method has been developed to incorporate the local three-dimensional shell behavior of two concentric tubes in the two-dimensional beam modeling of the problem. The two dimensional modeling of fuel channels in CANDU pressurized heavy water nuclear reactors is used in lieu of a more accurate three dimensional finite element approach in order to reduce the on-line simulation time which greatly affects the SLAR (Spacer Location And Repositioning) maintenance operation cost during outage. However, effort must be made to include the three-dimensional shell behavior of these channels into the two-dimensional modeling. In recent studies a nonlinear force-dependent model for contact stiffness between the calandria tube and pressure tube has been developed. However, local deformation of calandria the tube at spacer locations due to in-reactor creep leads to settling of the spacer into the calandria tube that consequently reduces the gap between the two tubes. In this work, the effect of local deformation (elastic and creep) of calandria tubes on modeling of contact at spacer locations is assessed using a three dimensional finite element code. The result is incorporated into a two-dimensional beam model of the problem as a reduction in size of the spacers that separate the two tubes. It is shown that the proposed method increases the accuracy of prediction of contact time and the spacer. In general, the method described in this paper suggests a way to incorporate local shell deformation into beam models of slender shell structure.