Elastic-Plastic Behaviour Near a Crack Tip of a Strip with a Crack under Tension and the Factor Controlling the Behaviour. Examination Based on FEM Analysis.

The present study proposes an efficient scheme to estimate elastic-plastic buckling load of a shallow grid dome stiffened by diagonal braces. The dome is circular in plan. It is assumed to be subject to a uniform vertical load and to be supported by a substructure composed of columns and anti-earthquake braces. Based on FEM parametric studies considering various configurations and degrees of local imperfections, a set of formulations are presented to estimate the elastic-plastic buckling load. In the scheme, the linear buckling load, elastic buckling load, and imperfection sensitivity are first presented in terms of related parameters, and the elasticplastic buckling load is then estimated by a semi-empirical formula in terms of generalized slenderness ratio using a corresponding plastic load. For the plastic load, the present scheme adopts a procedure that it is calculated by a linear elastic FEM analysis, while an alternative formula for the plastic load is also proposed based on a shell membrane theory. The validity of the estimation scheme is finally confirmed through comparison with the results based on FEM nonlinear analysis. The formulations are so efficient and simple that the estimation may be conducted for preliminary design purposes almost with a calculator. .

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Elastic-Plastic FEM Analysis of Deformations of a Cylinder Subjected to Severe Uniaxial and Bilateral Compression by Flat Plates

ASME 1991 Computers in Engineering Conference: Volume 2 — Finite Elements/Computational Geometry; Computers in Education; Robotics and Controls ◽

10.1115/cie1991-0108 ◽

1991 ◽

Author(s):

M. Gotoh ◽

Y. Shibata

Keyword(s):

Compressive Force ◽

Fem Analysis ◽

Plane Stress State ◽

Deformation Pattern ◽

Lateral Compression ◽

The Finite Element Method ◽

Ring Plane ◽

Flat Plates ◽

Elastic Plastic ◽

Plastic Forming

Abstract Uni-lateral and bi-lateral elastic-plastic compressions of a circular cylinder with three different wall thicknesses by flat plates are numerically analysed by the Finite Element Method (FEM). J2-flow theory (J2F), and J2-Gotoh’s corner theory (J2G) which was previously proposed by one of the authors are used as the constitutive equations. In the case of uni-lateral compression, the cylinder is compressed up to a completely flattened shape, which is considered a kind of plastic forming processes. The deformed shapes and the compressive force are predicted better by J2G than by J2F. The spring-back behaviours are also analysed by imposing unloading process during deformation. The deformation process in the compression of a ring (plane stress state) and a spherical shell (axi-symmetric state) is also analysed. In the case of bi-lateral compression, the process is considered a kind of square-tube forming. In its final stage, the cylinder deforms into a completely unexpected shape which could be thought of as a square tube reinforced with ribs. The J2G allows the process to proceed at a lower compressive force than that for J2F. The effect of n-value (the strain-hardedning exponent) on the deformation pattern is also discussed.

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A Simplified Method Study of Aluminium Alloy Fatigue Crack Tip Parameters Computed by Elastic-Plastic Finite Element Model

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.97-101.2748 ◽

2010 ◽

Vol 97-101 ◽

pp. 2748-2751

Author(s):

Xin Song ◽

Jing Zhong Xiang ◽

Jia Zhen Zhang

Keyword(s):

Finite Element ◽

Fatigue Crack ◽

Aluminium Alloy ◽

Crack Tip ◽

Element Model ◽

Crack Model ◽

Dynamic Crack ◽

Elastic Plastic ◽

Static Crack ◽

Element Computation

Fatigue crack propagation of aluminium alloy 7049-OA has been studied by non-linear finite element business-oriented software ABAQUS, and elastic-plastic finite element models of static fatigue crack and dynamic fatigue crack of center crack panel (CCP) specimens are also built. Based on the finite element computation results, the differences of stress and crack opening displacement around crack tip of static crack model have been compared with those of dynamic crack model. The compared results showed that the finite element computation results of dynamic crack model can be replaced by the results calculated by the static crack model. Fatigue crack tip parameters of aluminium alloy CCP specimens can be calculated by elastic-plastic finite element model of static crack. This is an effective method to cut down the computation expense and promote the computational efficiency.

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