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Stress concentration

About: Stress concentration is a research topic. Over the lifetime, 23250 publications have been published within this topic receiving 422911 citations.


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Proceedings ArticleDOI
TL;DR: In this paper, a 3D sequentially coupled finite element (FE) model was developed to investigate the thermomechanical responses in the selective laser melting (SLM) process, and the model was applied to test different scanning strategies and evaluate their effects on part temperature, stress and deformation.
Abstract: Selective laser melting (SLM) has emerged as one of the primary metal additive manufacturing technologies used for many applications in various industries such as medical and aerospace sectors. However, defects such as part distortion and delamination resulted from process-induced residual stresses are still one of the key challenges that hinder widespread adoptions of SLM. For process parameters, the laser beam scanning path will affect the thermomechanical behaviors of the build part, and thus, altering the scanning pattern may be a possible strategy to reduce residual stresses and deformations through influencing the heat intensity input distributions. In this study, a 3D sequentially coupled finite element (FE) model was developed to investigate the thermomechanical responses in the SLM process. The model was applied to test different scanning strategies and evaluate their effects on part temperature, stress and deformation. The major results are summarized as follows. (1) Among all cases tested, the out-in scanning pattern has the maximum stresses along the X and Y directions; while the 45° inclined line scanning may reduce residual stresses in both directions. (2) Large directional stress differences can be generated by the horizontal line scanning strategy. (3) X and Y directional stress concentrations are shown around the edge of the deposited layers and the interface between the deposited layers and the substrate for all cases. (4) The 45° inclined line scanning case also has a smaller build direction deformation than other cases.

292 citations

Journal ArticleDOI
TL;DR: In this paper, a comparison of the line tension effect with observed increases in strength in brittle matrix composites is made, showing that line tension is the major contribution to the strength increase for brittle obstacles.
Abstract: Cracks in brittle materials can be impeded by obstacles in the form of second phase dispersions. The crack tends to bow out between obstacles forming secondary semi-elliptical flaws. The strength is determined by the stress to propagate these secondary cracks. Stress calculations show that this depends on the ratios of the obstacle dimensions and the obstacle spacing and, except for large relative obstacle spacings, the stress is larger than the stress to extend the primary crack. Second phase dispersions will usually increase strength, therefore, through an effect equivalent to the ‘line tension effect’ observed for dislocation motion. A comparison of the calculated ‘line tension effect’ with observed increases in strength in brittle matrix composites shows that line tension is the major contribution to the strength increase for brittle obstacles, but only a minor contribution for fibre composites, and probably a minor contribution for ductile obstacles.

289 citations

Journal ArticleDOI
L. B. Freund1
TL;DR: In this paper, the authors determined the stress intensity of a half-plane crack extending non-uniformly in an isotropic elastic solid subjected to general loading and the Griffith fracture criterion was applied to obtain an equation of motion for the crack tip which was consistent with the assumptions of this criterion.
Abstract: The stress intensity factor of a half-plane crack extending non-uniformly in an isotropic elastic solid subjected to general loading is determined. The loading is applied in such a way that a state of plane strain exists and that crack extension takes place in Mode I. The crack tip is initially at rest and then moves in an arbitrary way in the plane of the crack. In the process of obtaining the stress intensity factor, the complete elastic field is determined for a crack which starts from some initial position, extends at a constant rate for some time, and then suddenly stops. Once the stress intensity factor is known for arbitrary motion of the crack tip, the Griffith fracture criterion is applied to obtain an equation of motion for the crack tip which is consistent with the assumptions of this criterion. Numerical results are included for the stress intensity factor and for the velocity-dependent term in the equation of motion.

288 citations

Journal ArticleDOI
TL;DR: In this paper, a statistical theory of material strength is proposed, where the strength of the elements is assumed to be a statistic a quantity, and as the material is loaded elements fracture randomly throughout the body causing localized stress concentrations.
Abstract: A Statistical theory of material strength is proposed. Materials are considered to be imperfect heterogeneous continua composed of discrete volume elements whose characteristics are related to material structure and imperfections. The strength of the elements is assumed to be a statistic a quantity, and as the material is loaded elements fracture randomly throughout the body causing localized stress concentrations. The accumulation of these breaks results in overall failure. By relating strength to material structure this theory attempts to bridge the gap between the microscopic and continuum approaches to fracture mechanics. The theory is applied to composite materials reinforced with whiskers and continuous fibers. Comparisons with experimental data show good agreement. Results for whisker-reinforced composites appear to provide a good prediction of strength and an explanation of the disparity between the strength of individual whiskers and the strength of the composites made from them.

288 citations

Book
01 Jul 1977
TL;DR: In this paper, the authors discuss the concepts of force, stress, strain, and displacement in the theory of elasticity, and propose a finite element model for stress and strain analysis.
Abstract: 1 Basic Concepts of Force, Stress, Strain, and Displacement 2 Stress and Strain. Transformations, Equilibrium, and Compatibility3 Fundamental Formulations of Stress, Strain, and Deflection4 Concepts from the Theory of Elasticity5 Topics from Advanced Mechanics of Materials6 Energy Techniques in Stress Analysis7 Strength Theories and Design Methods8 Experimental Stress Analysis9 Introduction to the Finite Element Method10 Finite Element Modeling TechniquesAppendicesA SI and USCU ConversionsB Properties of Cross SectionsC Beams in BendingD Singularity FunctionsE Principal Second-area MomentsF Stress Concentration FactorsG Strain Gage Rosette EquationsH Corrections for Transverse Sensitivity of Strain GagesI Matrix Algebra and Cartesian Tensors

287 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202373
2022220
2021628
2020642
2019608
2018581