The Experts below are selected from a list of 591708 Experts worldwide ranked by ideXlab platform
Raouf Fathallah - One of the best experts on this subject based on the ideXlab platform.
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Prediction and comparison of High-Cycle Fatigue behavior of ultrasonic and conventional shot-peened parts
The International Journal of Advanced Manufacturing Technology, 2019Co-Authors: S. Manchoul, R. Ben Sghaier, R. Seddik, Raouf FathallahAbstract:This paper proposes an engineering approach to investigate the High-Cycle Fatigue performance of shot-peened parts. The effects of the ultrasonic and conventional shot peening treatments on the Fatigue characteristic of AISI 316 l and Waspaloy materials are investigated and compared. This approach consists in (i) developing two 3D finite element models of ultrasonic and conventional shot peening treatments, (ii) predicting initial shot peening surface modifications induced by both models (residual stresses, equivalent plastic strains, superficial damage values, and micro-geometrical irregularities), (iii) evaluating the redistribution of the initial surface modifications after few cyclic loadings, and (iv) deducing the Fatigue performance of ultrasonic and conventional shot-peened parts for tensile loadings based on the High-Cycle Fatigue indicator ISP%. This attempt shows that both treatments exhibit significant potential for increasing the High-Cycle Fatigue strength of peened targets. However, the degree of Fatigue performance improvement is more obvious for the ultrasonic shot peening treatment. The obtained results are physically coherent and in good agreement with the previous experimental investigations found in the literature.
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High Cycle Fatigue behavior prediction of shot-peened parts
International Journal of Fatigue, 2004Co-Authors: Raouf FathallahAbstract:This paper presents an approach to predict High Cycle Fatigue behavior of shot-peened parts based on the multi-axial High Cycle Fatigue criteria of Crossland and Dang Van. The induced shot peening modifications on the surface layers, which are: (i) in-depth profile of compressive residual stresses, (ii) superficial work-hardening, (iii) surface finish imperfections, (iv) superficial defects, have been taken into account. This approach has been applied to a case of a shot-peened ductile steel SAE 3415 using two conditions: (i) a standard condition of 100% coverage (ii) a severe condition of 1000% coverage (High exposure time). This approach allows to evaluate all the effects of the induced shot peening modifications at the surface and in deeper layers. Good agreement has been observed between the predicted results and those obtained from experimental investigations. A computational procedure has been proposed to predict either High Cycle Fatigue strength enhancement or degradation of shot-peened parts.
Anders Klarbring - One of the best experts on this subject based on the ideXlab platform.
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Topology optimization using a continuous-time High-Cycle Fatigue model
Structural and Multidisciplinary Optimization, 2020Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We propose a topology optimization method that includes High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach where the evolution of damage in each point of the design domain is governed by a system of ordinary differential equations, which employs the concept of a moving endurance surface being a function of the stress and back stress. Development of Fatigue damage only occurs when the stress state lies outside the endurance surface. The Fatigue damage is integrated for a general loading history that may include non-proportional loading. Thus, the model avoids the use of a Cycle-counting algorithm. For the global High-Cycle Fatigue constraint, an aggregation function is implemented, which approximates the maximum damage. We employ gradient-based optimization, and the Fatigue sensitivities are determined using adjoint sensitivity analysis. With the continuous-time Fatigue model, the damage is load history dependent and thus the adjoint variables are obtained by solving a terminal value problem. The capabilities of the presented approach are tested on several numerical examples with both proportional and non-proportional loads. The optimization problems are to minimize mass subject to a High-Cycle Fatigue constraint and to maximize the structural stiffness subject to a High-Cycle Fatigue constraint and a limited mass.
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An Evolution-Based High-Cycle Fatigue Constraint in Topology Optimization
EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization, 2018Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We develop a topology optimization method including High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach, which uses the concept of a moving endurance surface as a function of the stress history and back stress evolution. The development of damage only occurs when the stress state lies outside the endurance surface. Furthermore, an aggregation function, which approximates the maximum Fatigue damage, is implemented. As the optimization workflow is sensitivity-based, the Fatigue sensitivities are determined using an adjoint sensitivity analysis. The capabilities of the presented approach are tested on numerical models where the problem is to maximize the stiffness subject to High-Cycle Fatigue constraints.
Shyam Suresh - One of the best experts on this subject based on the ideXlab platform.
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Topology optimization using a continuous-time High-Cycle Fatigue model
Structural and Multidisciplinary Optimization, 2020Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We propose a topology optimization method that includes High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach where the evolution of damage in each point of the design domain is governed by a system of ordinary differential equations, which employs the concept of a moving endurance surface being a function of the stress and back stress. Development of Fatigue damage only occurs when the stress state lies outside the endurance surface. The Fatigue damage is integrated for a general loading history that may include non-proportional loading. Thus, the model avoids the use of a Cycle-counting algorithm. For the global High-Cycle Fatigue constraint, an aggregation function is implemented, which approximates the maximum damage. We employ gradient-based optimization, and the Fatigue sensitivities are determined using adjoint sensitivity analysis. With the continuous-time Fatigue model, the damage is load history dependent and thus the adjoint variables are obtained by solving a terminal value problem. The capabilities of the presented approach are tested on several numerical examples with both proportional and non-proportional loads. The optimization problems are to minimize mass subject to a High-Cycle Fatigue constraint and to maximize the structural stiffness subject to a High-Cycle Fatigue constraint and a limited mass.
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An Evolution-Based High-Cycle Fatigue Constraint in Topology Optimization
EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization, 2018Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We develop a topology optimization method including High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach, which uses the concept of a moving endurance surface as a function of the stress history and back stress evolution. The development of damage only occurs when the stress state lies outside the endurance surface. Furthermore, an aggregation function, which approximates the maximum Fatigue damage, is implemented. As the optimization workflow is sensitivity-based, the Fatigue sensitivities are determined using an adjoint sensitivity analysis. The capabilities of the presented approach are tested on numerical models where the problem is to maximize the stiffness subject to High-Cycle Fatigue constraints.
Stefan B. Lindström - One of the best experts on this subject based on the ideXlab platform.
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Topology optimization using a continuous-time High-Cycle Fatigue model
Structural and Multidisciplinary Optimization, 2020Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We propose a topology optimization method that includes High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach where the evolution of damage in each point of the design domain is governed by a system of ordinary differential equations, which employs the concept of a moving endurance surface being a function of the stress and back stress. Development of Fatigue damage only occurs when the stress state lies outside the endurance surface. The Fatigue damage is integrated for a general loading history that may include non-proportional loading. Thus, the model avoids the use of a Cycle-counting algorithm. For the global High-Cycle Fatigue constraint, an aggregation function is implemented, which approximates the maximum damage. We employ gradient-based optimization, and the Fatigue sensitivities are determined using adjoint sensitivity analysis. With the continuous-time Fatigue model, the damage is load history dependent and thus the adjoint variables are obtained by solving a terminal value problem. The capabilities of the presented approach are tested on several numerical examples with both proportional and non-proportional loads. The optimization problems are to minimize mass subject to a High-Cycle Fatigue constraint and to maximize the structural stiffness subject to a High-Cycle Fatigue constraint and a limited mass.
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An Evolution-Based High-Cycle Fatigue Constraint in Topology Optimization
EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization, 2018Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We develop a topology optimization method including High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach, which uses the concept of a moving endurance surface as a function of the stress history and back stress evolution. The development of damage only occurs when the stress state lies outside the endurance surface. Furthermore, an aggregation function, which approximates the maximum Fatigue damage, is implemented. As the optimization workflow is sensitivity-based, the Fatigue sensitivities are determined using an adjoint sensitivity analysis. The capabilities of the presented approach are tested on numerical models where the problem is to maximize the stiffness subject to High-Cycle Fatigue constraints.
Carl-johan Thore - One of the best experts on this subject based on the ideXlab platform.
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Topology optimization using a continuous-time High-Cycle Fatigue model
Structural and Multidisciplinary Optimization, 2020Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We propose a topology optimization method that includes High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach where the evolution of damage in each point of the design domain is governed by a system of ordinary differential equations, which employs the concept of a moving endurance surface being a function of the stress and back stress. Development of Fatigue damage only occurs when the stress state lies outside the endurance surface. The Fatigue damage is integrated for a general loading history that may include non-proportional loading. Thus, the model avoids the use of a Cycle-counting algorithm. For the global High-Cycle Fatigue constraint, an aggregation function is implemented, which approximates the maximum damage. We employ gradient-based optimization, and the Fatigue sensitivities are determined using adjoint sensitivity analysis. With the continuous-time Fatigue model, the damage is load history dependent and thus the adjoint variables are obtained by solving a terminal value problem. The capabilities of the presented approach are tested on several numerical examples with both proportional and non-proportional loads. The optimization problems are to minimize mass subject to a High-Cycle Fatigue constraint and to maximize the structural stiffness subject to a High-Cycle Fatigue constraint and a limited mass.
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An Evolution-Based High-Cycle Fatigue Constraint in Topology Optimization
EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization, 2018Co-Authors: Shyam Suresh, Stefan B. Lindström, Carl-johan Thore, Bo Torstenfelt, Anders KlarbringAbstract:We develop a topology optimization method including High-Cycle Fatigue as a constraint. The Fatigue model is based on a continuous-time approach, which uses the concept of a moving endurance surface as a function of the stress history and back stress evolution. The development of damage only occurs when the stress state lies outside the endurance surface. Furthermore, an aggregation function, which approximates the maximum Fatigue damage, is implemented. As the optimization workflow is sensitivity-based, the Fatigue sensitivities are determined using an adjoint sensitivity analysis. The capabilities of the presented approach are tested on numerical models where the problem is to maximize the stiffness subject to High-Cycle Fatigue constraints.