Author
K. Dang Van
Bio: K. Dang Van is an academic researcher from École Polytechnique. The author has contributed to research in topics: Shakedown & Fatigue limit. The author has an hindex of 17, co-authored 22 publications receiving 1141 citations.
Topics: Shakedown, Fatigue limit, Finite element method, Welding, Fretting
Papers
More filters
TL;DR: In this article, the authors present a global approach to the design of structures that experience thermomechanical fatigue loading, which has been applied successfully in the case of cast-iron exhaust manifolds.
Abstract: This paper presents a global approach to the design of structures that experience thermomechanical fatigue loading, which has been applied successfully in the case of cast‐iron exhaust manifolds. After a presentation of the design context in the automotive industry, the important hypotheses and choices of this approach, based on a thermal 3D computation, an elastoviscoplastic constitutive law and the dissipated energy per cycle as a damage indicator associated with a failure criterion, are first pointed out. Two particular aspects are described in more detail: the viscoplastic constitutive models, which permit a finite element analysis of complex structures and the fatigue criterion based on the dissipated energy per cycle. The FEM results associated with this damage indicator permit the construction of a design curve independent of temperature; an agreement is observed between the predicted durability and the results of isothermal as well as non isothermal tests on specimens and thermomechanical fatigue tests on real components on an engine bench. These results show that thermomechanical fatigue design of complex structures can be performed in an industrial context.
123 citations
TL;DR: In this article, a 3D mixed finite element model based on a computational fluid dynamics package is used to establish the material flow, the temperature and the pressure fields during the process, and the residual stresses of a friction stir welded assembling are evaluated.
Abstract: This paper presents a computational method for the simulation of a welding process called friction stir welding. This simulation is divided into two main steps. The first one uses an Eulerian description of the thermomechanical problem; a 3D mixed finite element model based on a computational fluid dynamics package is used to establish the material flow, the temperature and the pressure fields during the process. These results are compared with experimental data. The second step of the simulation is more original. A part of the initial geometry is extracted in order to evaluate the material flow in a local domain around the tool. A steady state algorithm is then used to calculate the residual state induced by the process. This calculation takes into account the whole mechanical history of the material because the algorithm is based on an integration along the trajectories of the particles. Finally, the residual stresses of a friction stir welded assembling are evaluated. It should be noted that only the steady state phase of the process is simulated, which leads to a substantial reduction of computational time.
99 citations
TL;DR: In this paper, a steady-state simulation of friction stir welding based on a prior computational method developed in [Bastier, A., Maitournam, M.H., Dang Van, K., Roger, F., 2006] is presented.
88 citations
TL;DR: In this article, a finite element method was developed for high cycle fatigue under periodic constant load systems, which can be used for finite element-based CAD design of structural components, and the authors described a CAD system that can be derived from this analysis.
Abstract: — We aim to develop a systematic method of designing structures, by finite element methods, for high cycle fatigue under periodic constant load systems. After having defined a precise terminology, we quickly list those multiaxial fatigue criteria which can be found in the literature. Some criteria, derived from a microscopic approach (Dang Van's, Papadopoulos' and Deperrois' criteria) are extensively presented. The criteria which can be reasonably retained for numerical analyses of structures are underlined and compared to one another. As a conclusion, we describe a high cycle fatigue CAD system which can be derived from this analysis.
87 citations
Cited by
More filters
TL;DR: In this article, the authors deal with the fundamental understanding of the process and its metallurgical consequences, focusing on heat generation, heat transfer and plastic flow during welding, elements of tool design, understanding defect formation and the structure and properties of the welded materials.
1,811 citations
TL;DR: A comprehensive body of knowledge has built up with respect to the friction stir welding (FSW) of aluminium alloys since the technique was invented in 1991 is reviewed in this article, including thermal history and metal flow, before discussing how process parameters affect the weld microstructure and the likelihood of entraining defects.
Abstract: The comprehensive body of knowledge that has built up with respect to the friction stir welding (FSW) of aluminium alloys since the technique was invented in 1991 is reviewed The basic principles of FSW are described, including thermal history and metal flow, before discussing how process parameters affect the weld microstructure and the likelihood of entraining defects After introducing the characteristic macroscopic features, the microstructural development and related distribution of hardness are reviewed in some detail for the two classes of wrought aluminium alloy (non-heat-treatable and heat-treatable) Finally, the range of mechanical properties that can be achieved is discussed, including consideration of residual stress, fracture, fatigue and corrosion It is demonstrated that FSW of aluminium is becoming an increasingly mature technology with numerous commercial applications In spite of this, much remains to be learned about the process and opportunities for further research a
956 citations
TL;DR: In this paper, the authors provide a concise assessment of some commonly used high-cycle fatigue criteria and check their predictive capabilities against synchronous out-of-phase bending and torsion experimental results.
562 citations
TL;DR: In this article, three-dimensional viscoplastic flow and heat transfer during friction stir welding of mild steel was investigated both experimentally and theoretically, and the equations of conservation of mass, momentum and energy were solved in three dimensions using spatially variable thermo-physical properties and a methodology adapted from well established previous work in fusion welding.
556 citations
TL;DR: In this paper, a range of uniquely multi-scale hierarchical structures have been successfully designed and fabricated by tailoring reinforcement distribution for discontinuous metal matrix composites in order to obtain superior performance.
537 citations