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Tesi etd-01232015-111424

Thesis type
Tesi di laurea magistrale
email address
Inverse analysis techniques for the identification of Chaboche's hardening model parameters
Corso di studi
relatore Prof. Bertini, Leonardo
relatore Prof. Santus, Ciro
relatore Ing. Monelli, Bernardo Disma
Parole chiave
  • Kinematic hardening
  • Calibration methods
  • Parameter determination
  • Algorithms implementation
  • Genetic Algorithm
  • Constitutive modeling and simulation
  • Ratcheting
  • Cyclic plasticity
Data inizio appello
Secretata d'ufficio
Data di rilascio
Riassunto analitico
The main goal of this work is the investigation of the procedures for material characterization aimed at Chaboche hardening model.
This will be done in order to perform stress analysis of structural components under cyclical loads. The implementation of complex material model, such as the Chaboche hardening model, allows to obtain an improvement in the accuracy of simulation’s results through FEM compared with the current state which foresees the use of simple rheology models like Hollomon’s model or Ramberg-Osgood’s model. Traditionally this lack has been faced through the use of factors of safety, which are developed and refined on the basis of the experience and historical backgrounds. For systems where efficient design is of the extreme importance like in gas turbine design, it is possible that the traditional factors of safety may be over conservative, so that optimal efficiency cannot be achieved. The implementation of complex material models allows simulating the real material behavior. The results are more accurate and allow reducing the traditional factors of safety, consequently lead to a significant improvement in the designing of structural components.
The process of material characterization has been developed through the following phases:
• Choose of the experimental data needed to characterize cyclic plastic behavior of metallic material, in particular steel.
• Choose the constitutive laws, which allows the calculations of stress and strain in plasticity.
• Choose the methodology for the identification of material’s parameters.
• Try to replicate and describe the procedures to define material’s parameters, thus, through implementation into language program like MATLAB, is performed a comparison between experimental data and simulated ones.
• Choose the best methodology for parameters identification.
• Use of FEM code (ANSYS) to validate and verify that the material’s parameters founded produce the expected results.