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Title: Identification of Damage Parameters in the commercial code LS-DYNA
Authors: Menezes, Bernardo 
Orientador: Doig, Maria
Oliveira, Marta
Keywords: Damage; Parameter identification; Optimization; Sensitivity analysis; Tensile test; Nakajima tests
Issue Date: 24-Jul-2015
Serial title, monograph or event: Tese de Mestrado
Abstract: During plastic deformation, materials can suffer damage. The rate at which this damage progresses varies significantly from one material to another. In order to improve the ability of finite element analysis for failure prediction, continuum damage models are being integrated in codes, in order to contribute for enhancing the optimization of sheet metal forming processes. An example is the integration of the enhanced Lemaitre’s damage model in the LS-DYNA. However, to explore the potentialities of this model, it is important to improve the knowledge concerning the identification of its parameters. The present work focus on the development of a strategy to perform the identification of these model parameters. In this context, sensitivity analysis and optimization tools available on LS-OPT were explored. The inverse damage parameters identification strategy is developed considering the availability of force-displacement experimental results from: uniaxial tensile and Nakajima tests. The material orthotropic behaviour and the isotropic hardening parameters are identified using the results from uniaxial tensile tests. Based on the sensitivity analysis performed to the damage parameters, the identification procedure proposed includes five damage parameters. The procedure is based on the application of the Adaptive Simulated Annealing algorithm to metamodels, built considering a Sequential Response Surface Methodology, in order to minimize the computational time. The results show that the procedure is sensitive to the user-defined starting point. In this context, it is not possible to state which of the solutions obtained corresponds to the best description of the material mechanical behaviour. A strategy to reduce the number of parameters is also proposed, based on the analytical calculation of the initial damage energy release rate. This enables the identification of the damage parameters with a similar accuracy in a lower number of iterations.
Rights: embargoedAccess
Appears in Collections:FCTUC Eng.Mecânica - Teses de Mestrado

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