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Stress field

About: Stress field is a research topic. Over the lifetime, 11926 publications have been published within this topic receiving 226417 citations.


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TL;DR: In this paper, a twenty-node hexahedron element is employed in each layer for the displacement field, and the equilibrium equation is enforced by the variational principle, which is derived from the Hellinger-Reissner principle.
Abstract: The variational principle of this element can be derived from the Hellinger-Reissner principle through dividing six stress components into a flexural part (σ x , σ y , τ xy , σ z ) and a transverse shear part (τ xy , τ yz ). The element stiffness matrix can be formulated by assuming a stress field only for transverse shear stresses, while all the others are obtained from an assumed displacement field. A twenty-node hexahedron element is employed in each layer for the displacement field. The equilibrium equation is enforced by the variational principle

58 citations

Journal ArticleDOI
TL;DR: A topology structural optimization framework with adaptive mesh refinement and stress-constraints that combines a volume fraction filter to impose a minimum design feature size, the RAMP penalization to generate “black-and-white designs” and a RAMP-like stress definition to resolve the "stress singularity problem".
Abstract: We present a topology structural optimization framework with adaptive mesh refinement and stress-constraints. Finite element approximation and geometry representation benefit from such refinement by enabling more accurate stress field predictions and greater resolution of the optimal structural boundaries. We combine a volume fraction filter to impose a minimum design feature size, the RAMP penalization to generate “black-and-white designs” and a RAMP-like stress definition to resolve the “stress singularity problem.” Regions with stress concentrations dominate the optimized design. As such, rigorous simulations are required to accurately approximate the stress field. To achieve this goal, we invoke a threshold operation and mesh refinement during the optimization. We do so in an optimal fashion, by applying adaptive mesh refinement techniques that use error indicators to refine and coarsen the mesh as needed. In this way, we obtain more accurate simulations and greater resolution of the design domain. We present results in two dimensions to demonstrate the efficiency of our method.

58 citations

Journal ArticleDOI
TL;DR: In this article, the authors used edge-cracked bend bar specimens loaded in anti-symmetric and symmetric four-point bend configurations to investigate fracture micro-mechanisms of four grades of steel.

58 citations

Journal ArticleDOI
TL;DR: In this article, the authors study the near-field generated by Haskell9s rectangular fault model used extensively to interpret seismic data and find an exact solution for the near field particle velocities in the case of a step function source slip history.
Abstract: We study the near-field generated by Haskell9s rectangular fault model used extensively to interpret seismic data. By means of the Cagniard-de Hoop method we have been able to find an exact solution for the near-field particle velocities in the case of a step-function source slip history. The results show that there are two distinct regions of radiation. One is a cylindrical region in front of the fault where two-dimensional approximations are valid and result in a substantial reduction of computation. In the rest of space the field is dominated by spherical waves radiated from the corners of the dislocation. These waves are much more complicated to calculate. First motion approximations demonstrate that the cylindrical waves are stronger than the spherical waves; in particular, infinite accelerations at the cylindrical wave fronts are predicted even for ramp sourcetime functions. The stress field on the fault plane generated by this dislocation is also calculated. Strong stress singularities of type r −1 are found all around the edges of the fault. These singularities are a consequence of the assumption of constant dislocation across the fault width. They may only be eliminated by smoothing the dislocation near the fault edges. These singularities are so strong that an infinite averaged stress drop on the fault is predicted independently of any source parameters. As a consequence, the Haskell model is essentially a long-period model of faulting.

58 citations

Journal ArticleDOI
TL;DR: In this article, five models for near-surface crustal stresses induced by gravity and horizontal deformation and the influence of rock property contrasts, rock strength, and stress relaxation on these stresses are presented.
Abstract: Five models for near-surface crustal stresses induced by gravity and horizontal deformation and the influence of rock property contrasts, rock strength, and stress relaxation on these stresses are presented. Three of the models—the lateral constraint model, the model for crustal stresses caused by horizontal deformation, and the model for the effects of anisotropy—are linearly elastic. The other two models assume that crustal rocks are brittle or viscoelastic in order to account for the effects of rock strength and time on near-surface stresses. It is shown that the lateral constraint model is simply a special case of the combined gravity-and deformation-induced stress field when horizontal strains vanish and that the inclusion of the effect of rock anisotropy in the solution for crustal stresses caused by gravity and horizontal deformation broadens the range for predicted stresses. It is also shown that when stress levels in the crust reach the limits of brittle rock strength, these stresses become independent of strain rates and that stress relaxation in ductile crustal rocks subject to constant horizontal strain rates causes horizontal stresses to become independent of time in the long term.

58 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023245
2022517
2021392
2020416
2019410
2018388