M. Aghaie-khafri
Faculty of Materials Science and Engineering, K.N. Toosi University of Technology, Postal Code: 1999143344, Tehran, Iran
[ 1 ] - Optimization of thermomechanical parameters to produce an ultra-high strength compressor disk
Structural steels with very high strength levels are often referred to as ultrahigh-strength steels (UHSS). The usage of UHSS has been extensively studied in aerospace industries and offshore platforms. In this study, medium carbon low alloy steel (AMS6305) was thermomechanicaly treated to obtain an ultra-high strength bainitic steel for aircraft engine compressor disk. A novel themomechanical ...
[ 2 ] - Cold work simulation of hole expansion process and its effect on crack closure
Using cold working fastener holes is a simple life enhancement procedure that strengthens metallic components by retarding crack growth around a hole. In the present paper, the residual stress field that is induced by the hole expansion process is obtained based on different material models namely elastic perfect plastic, isotropic hardening and kinematic hardening using three-dimensional finit...
[ 3 ] - A comparison between numerical and analytical modeling of ECAP
Recent developments in nanostructured products draw considerable attention to ultrafine grained materials. These materials are normally manufactured by different severe plastic deformation (SPD) methods. In the present study, analytical models and finite element method (FEM) are used to calculate strain imposed to a specimen that was deformed by equal channel angular pressing (ECAP). In additio...
[ 4 ] - On the Magneto-Thermo-Elastic Behavior of a Functionally Graded Cylindrical Shell with Pyroelectric Layers Featuring Interlaminar Bonding Imperfections Rested in an Elastic Foundation
The behavior of an exponentially graded hybrid cylindrical shell subjected to an axisymmetric thermo-electro-mechanical loading placed in a constant magnetic field is investigated. The hybrid shell is consisted of a functionally graded host layer embedded with pyroelectric layers as sensor and/or actuator that can be imperfectly bonded to the inner and the outer surfaces of a shell. The shell...
[ 5 ] - Application of Case I and Case II of Hill’s 1979 Yield Criterion to Predict FLD
Forming limit diagrams (FLDs) are calculated based on both the Marciniak and Kuczynski (M-K) model and the analysis proposed by Jones and Gillis (J-G). J-G analysis consisted of plastic deformation approximation by three deformation phases. These phases consisted of homogeneous deformation up to the maximum load (Phase I), deformation localization under constant load (phase II) and local necki...
[ 6 ] - Effect of Compressive Residual Stress on the Corner Crack Growth
In the present study, plasticity induced crack closure (PICC) concept and three dimensional (3D) finite element methods (FEM) are used to study the effect of compressive residual stress field on the fatigue crack growth from a hole. To investigate the effect of compressive residual stress on crack opening levels and crack shape evolution, Carlson’s experiments were simulated. Crack shape evolut...
[ 7 ] - An Enhanced Viscoplastic Constitutive Model for Semi-Solid Materials to Analyze Shear Localization
Semi-solid materials undergo strain localization and shear band formation as a result of granular nature of semi-solid deformation. In the present study, to analyze the shear localization, a unified viscoplastic constitutive model was developed for the homogeneous flow. Then, a linearized analysis of the stability performed by examining the necessary condition for the perturbation growth. For t...
[ 8 ] - پیش‌بینی نمودار حد شکل‌دهی ورقها با شبیه‌سازی عددی آزمون‌های ناکازیما و مارسینیاک اصلاح شده
نمودار حد شکل‌دهی(FLD) عموما برای برآورد شکل‌پذیری ورقها مورد استفاده قرار می‌گیرد. استخراج نمودار‌های حد شکل‌دهی به صورت تجربی، مستلزم آزمایش‌های دقیق، صرف زمان و هزینه زیاد است. از این رو پژوهش‌های متعددی در استفاده از روش‌های تحلیلی و نرم‌افزارهای المان محدود برای تعیین این نمودار‌ها صورت گرفته است. در این پژوهش، منحنی‌های حد شکل‌دهی برای ورق آلومینیوم AA3105 از طریق شبیه‌سازی آزمون ناکاز...
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