MULTISCALE MODELING AND ANALYSIS OF FAILURE AND STABILITY DURING SUPERPLASTIC DEFORMATION -- UNDER DIFFERENT LOADING CONDITIONS

摘要: OF THESIS MULTISCALE MODELING AND ANALYSIS FAILURE STABILITY DURING SUPERPLASTIC DEFORMATION – UNDER DIFFERENT LOADING CONDITIONS Superplastic forming (SPF) is a valuable near net shape fabrication method, used to produce very complex, contoured and monolithic structures that are often lighter, stronger safer than the assemblies they replace. However, widespread industrial use of (SP) alloys hindered by number issues including low production rate limited predictive capabilities stability during deformation failure. Failure SPD may result from geometrical macroscopic instabilities and/or microstructural aspects. available failure criteria either based on or features do not account for both modes. The present study presents generalized multi-scale criterion SP materials, accounting aspects under various loading conditions. A combined model cavity nucleation plasticity controlled growth along with grain modified microstructure constitutive equation materials incorporated into Hart’s analysis develop proposed different Effects initial size, levels cavitation, strain, strain-rate sensitivity, grain-growth exponent optimum curves investigated,