Author: Mark Anthony James
Publisher:
ISBN:
Category :
Languages : en
Pages : 224

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 88

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Book Description

Author: Sylvie Pommier
Publisher: John Wiley & Sons
ISBN: 1118622693
Category : Technology & Engineering
Languages : en
Pages : 271

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Book Description
Novel techniques for modeling 3D cracks and their evolution in solids are presented. Cracks are modeled in terms of signed distance functions (level sets). Stress, strain and displacement field are determined using the extended finite elements method (X-FEM). Non-linear constitutive behavior for the crack tip region are developed within this framework to account for non-linear effect in crack propagation. Applications for static or dynamics case are provided.

Author: Narasimhan Ramarathnam
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 348

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Author: Meng R. Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 332

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Author: P. S. Lam
Publisher:
ISBN:
Category :
Languages : en
Pages : 36

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 102

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Book Description

Author: M. Salmon
Publisher:
ISBN:
Category : Computer programs
Languages : en
Pages : 60

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Book Description
A computer program is presented for the small strain analysis of plane structures in the strain hardening elastic-plastic range. The finite element displacement method is used to perform the linear analyses in the iterative scheme. Bar and constant strain isotropic plane stress triangles are available for use in constructing structural idealizations. The use of ten different sets of material properties, three different material laws, and incremental proportional loading are available as options. Good correlation is shown with available test data and theoretical solutions.

Author: Y. Yamada
Publisher:
ISBN:
Category : Compression
Languages : en
Pages : 17

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Book Description
Compression precracking has been used in a renewed effort to generate fatigue-crack growth rates in the threshold and near-threshold regimes, as an alternative to the traditional load-reduction procedure. But concerns have been expressed on the influence of tensile residual stresses resulting from compressive yielding at the crack-starter notch. This paper uses elastic-plastic, finite-element analyses to study the influence of the tensile residual stresses induced by compression precracking on simulated crack growth under constant-amplitude loading. High-fidelity finite-element models (60 000 to 160 000 DOF) using two-dimensional plane-stress analyses were used to model plastic yielding during compressive loading and simulated fatigue-crack growth through the tensile residual-stress field. The finite-element code was ZIP2D and the course mesh had an element size of 2 ?m. A refined mesh had an element size four times smaller (0.5 ?m) than the course mesh. Fatigue-crack growth and crack-closure effects were simulated over a wide range in stress ratios (R=0 to 0.8) and load levels, after compression precracking. The crack-tip-opening displacement (CTOD) concept was used to judge the extent of the influence on the tensile residual stresses and the stabilization of the crack-opening loads. It was found that the tensile residual stress field decayed as the crack grew under cyclic loading. Once the crack had reached one compressive plastic-zone size, the tensile residual-stress field had dissipated. However, the stabilization of the crack-opening loads and merging of the CTOD values with and without compression precracking was found to be about 1.5 to 2 times the compressive plastic-zone size at R=0 loading. The effects dissipated at smaller distances from the notch tip for the higher stress ratios. The present results have validated the crack-extension criterion that had been proposed for use in the compressive precracking threshold test method, beyond which, cracks are growing under constant-amplitude (steady-state) behavior.

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722873073
Category :
Languages : en
Pages : 100

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Book Description
ZIP2DL is a two-dimensional, elastic-plastic finte element program for stress analysis and crack growth simulations, developed for the NASA Langley Research Center. It has many of the salient features of the ZIP2D program. For example, ZIP2DL contains five material models (linearly elastic, elastic-perfectly plastic, power-law hardening, linear hardening, and multi-linear hardening models), and it can simulate mixed-mode crack growth for prescribed crack growth paths under plane stress, plane strain and mixed state of stress conditions. Further, as an extension of ZIP2D, it also includes a number of new capabilities. The large-deformation kinematics in ZIP2DL will allow it to handle elastic problems with large strains and large rotations, and elastic-plastic problems with small strains and large rotations. Loading conditions in terms of surface traction, concentrated load, and nodal displacement can be applied with a default linear time dependence or they can be programmed according to a user-defined time dependence through a user subroutine. The restart capability of ZIP2DL will make it possible to stop the execution of the program at any time, analyze the results and/or modify execution options and resume and continue the execution of the program. This report includes three sectons: a theoretical manual section, a user manual section, and an example manual secton. In the theoretical secton, the mathematics behind the various aspects of the program are concisely outlined. In the user manual section, a line-by-line explanation of the input data is given. In the example manual secton, three types of examples are presented to demonstrate the accuracy and illustrate the use of this program. Deng, Xiaomin and Newman, James C., Jr. Langley Research Center...