1,721,149 research outputs found
On geometrical effects in micro-resonators
No full textThe paper analyzes the nonlinear dynamic response of microresonators. A simple physical model of a single span beam axially constrained at both end, possibly with elastic constraints, is considered as representative of different common layout of microresonators. An analytical model, based on the Hamilton's principle, accounting for large displacements is presented and validated thanks to numerical finite element analyses. In order to widen the linear operation range of the device an optimal geometry of the resonator is proposed
A variationally consistent generalized variable formulation of the elastoplastic rate problem.
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Chemo-mechanical modelling of the external sulfate attack in concrete
Full text linkThis paper is focused on the modelling of the mechanical consequences of external sulfate attack in concrete structures under partially or fully saturated conditions. To this purpose a weakly coupled approach is developed: first the moisture content is computed through a simplified diffusion model, then a reactivediffusionmodelallowsforthecomputationoftheexpansiveproductsofthereactionoccurringbetweenthe aluminatesofthecementpasteandtheincomingsulfateions,finallythesolutionofanonlinearmechanical problem gives the expansion, the stress state and the degradation induced by the reaction. The mechanical problem makes use of a multiphase elasto-damage model, developed in this work and accounting for both chemical and mechanical damage. The model is validated by simulating various experimental tests on concrete specimens subject to external sulfate attack and then applied to the simulation of a reduced scale structure of a tunnel lining
Extremum, convergence and stability properties of the finite-increment problem in elastic-plastic boundary element analysis.
No full textThe boundary element (BE) analysis is formulated by a symmetric (Galerkin weightedresidual, double-integration) approach, rather than by a traditional collocation or by a nonsymmetric-Galerkin approach. The internal variable associative elastoplastic material model is discretized in time by a stepwise-holonomic, backward-difference integration scheme: it is then enforced in a weighted-average sense over cells and reformulated in terms of cell generalized variables. In the above context the following results are established under suitable constitutive hypotheses; • (a) a minimum characterization of the solution to the discretized step-problem in finite increments; • (b) a convergence theorem concerning a conventional iterative algorithm for solving this problem; • (c) a proof of the stability of the marching solution method, in the sense of non-amplification of errors along a finite step sequence. An illustrative example corroborates the theoretical results
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