scholarly journals Mode II Fracture of an Elastic-Plastic Sandwich Layer

2019 ◽  
Vol 87 (3) ◽  
Author(s):  
Emilio Martínez-Pañeda ◽  
I. Iván Cuesta ◽  
Norman A. Fleck
Keyword(s):  
Sandwich Plate ◽  
Numerical Solutions ◽  
Crack Tip ◽  
Mode Ii ◽  
Finite Width ◽  
Yield Model ◽  
Elastic Plastic ◽  
Strip Yield Model ◽  
Finite Crack ◽  
Crack Tip Plasticity

Abstract The shear strength of a pre-cracked sandwich layer is predicted, assuming that the layer is linear elastic or elastic-plastic, with yielding characterized either by the J2 plasticity theory or by a strip-yield model. The substrates are elastic and of dissimilar modulus to that of the layer. Two geometries are analyzed: (i) a semi-infinite crack in a sandwich layer, subjected to a remote mode II K-field and (ii) a center-cracked sandwich plate of finite width under remote shear stress. For the semi-infinite crack, the near-tip stress field is determined as a function of elastic mismatch, and crack tip plasticity is either prevented (the elastic case) or duly accounted for (the elastic-plastic case). Analytical and numerical solutions are then obtained for the center-cracked sandwich plate of the finite width. First, a mode II K-calibration is obtained for a finite crack in the elastic sandwich layer. Second, the analysis is extended to account for crack tip plasticity via a mode II strip-yield model of finite strength and finite toughness. The analytical predictions are verified by finite element simulations, and a failure map is constructed in terms of specimen geometry and crack length.

Comparison of Strip Yield and Net Section Plasticity Models for a Bar in Bending With a Single Edge Crack

2017 ◽  
Author(s):  
Wolf Reinhardt ◽  
Don Metzger
Keyword(s):  
Edge Crack ◽  
Large Scale ◽  
Stress Singularity ◽  
Crack Tip ◽  
Small Scale ◽  
Single Edge ◽  
Yield Model ◽  
Strip Yield Model ◽  
Crack Tip Plasticity ◽  
Stress And Deformation

The strip yield model is widely used to describe crack tip plasticity in front of a crack. In the strip yield model the stress in the plastic zone is considered as known, and stress and deformation fields can be obtained from elastic solutions using the condition that the crack tip stress singularity vanishes. The strip yield model is generally regarded to be valid to describe small scale plasticity at a crack tip. The present paper examines the behavior of the strip yield model at the transition to large-scale plasticity and its relationship to net section plasticity descriptions. A bar in bending with a single edge crack is used as an illustrative example to derive solutions and compare with one-sided and two-sided plasticity solutions.

Elastic-Plastic Analogy for Examination of Softening Response for Strip Yield Models

2020 ◽  
Author(s):  
Don Metzger ◽  
Wolf Reinhardt
Keyword(s):  
Analytical Solution ◽  
Inelastic Deformation ◽  
Load Capacity ◽  
Pure Bending ◽  
Yield Model ◽  
Elastic Plastic ◽  
Bending Load ◽  
Strip Yield Model ◽  
Linear Softening ◽  
Plastic Case

Abstract The manner in which the spread of inelastic deformation of a softening cohesive zone affects the load capacity is examined. The analysis makes use of an elastic-plastic analogy to the strip yield model applied to pure bending. The example of pure bending is one case where inelastic deformation contributes to enhancing the load capacity. The analytical solution to the elastic-plastic case is developed for zero hardening (baseline for strip yield case for which analytical solution is known) as well as for a range of linear softening rates. Evaluation of the results shows that the maximu m bending load capacity is always reached before the stress at the surface becomes zero.

Strip-Yield Modeling of Load-Time-Temperature Effects on Crack Growth in Engine Materials

2020 ◽  
Author(s):  
James C. Newman ◽  
Rani Sullivan
Keyword(s):  
Stress Relaxation ◽  
Crack Growth ◽  
Test Data ◽  
Crack Front ◽  
Crack Tip ◽  
Time Dependent ◽  
Yield Model ◽  
Linear Superposition ◽  
Strip Yield Model ◽  
Creep Deformations

Abstract Plastic and creep deformations around a crack front and in the wake of a moving crack under cyclic loading are implemented into the life-prediction code, FASTRAN (a strip-yield model). Creep deformations are modeled by stress relaxation around the crack-tip location, since the crack-front material is under displacement control due to the surrounding elastic material. Sinusoidal and trapezoidal loading are considered. A modified linear superposition model was used to compute the cyclic- and time-dependent damage, which was based on the stress-intensity-factor concept for creep-brittle materials. Application of the modified strip-yield model was made on two sets of test data on Inconel-718 alloy. The environments were laboratory air or helium gas. From the literature, the “environment” had been shown to be a major contributor to damage magnitudes. Thus, the time-dependent crack-growth constants were selected to match the test data. In addition, the effects of a small overload on time-dependent damage, and the effects of stress relaxation and varying temperatures on crack-opening stresses and cyclic crack-tip-opening displacements, were studied.

An Analysis for Crack Instability in Elastically Confined Yielding Regime

1984 ◽  
Vol 106 (4) ◽  
pp. 488-494 ◽  
Author(s):  
A. Zahoor
Keyword(s):  
Control Mode ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Yield Model ◽  
System A ◽  
Strip Yield Model ◽  
Loading System ◽  
Scale Yielding ◽  
Crack Tip Plasticity ◽  
Special Case

An analysis for crack instability is presented which utilizes a J-integral-based tearing modulus approach. In particular, a plane stress center-cracked panel which experiences elastically confined yielding is analyzed for a displacement controlled loading. The analysis assumes a compliant loading system, a special case of which leads to a load control mode of loading. The effects of the crack tip plasticity are taken into account by using the strip-yield model of Dugdale-Barenblatt. A method of predicting the amount of crack growth at the onset of instability is presented. Numerical results suggest that under conditions of small-scale yielding, crack instability can be achieved in materials having very low tearing modulus values.

Elastic-Plastic Finite Element Analysis of the Effect of the Compressive Loading on the Crack Tip Plasticity

2006 ◽  
Vol 324-325 ◽  
pp. 73-76
Author(s):  
J.Z. Zhang ◽  
Xiao Dong He ◽  
X. Song ◽  
Shan Yi Du
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Zone ◽  
Significant Contribution ◽  
Crack Opening ◽  
Compressive Loading ◽  
Crack Tip ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Crack Tip Plasticity

An elastic-plastic finite element analysis of the effect of the compressive loading on crack tip plasticity is presented. Two center-cracked panel specimens with different crack lengths are analysed under tension-compression loading. The size and shape of the crack tip reverse plastic zone, the crack opening profiles of the crack tip for short (0.1 mm) and long crack (2 mm) have been studied. The analysis shows that the compressive loading has a significant contribution towards the crack tip plasticity.

Elastic-Plastic Analysis of Cracks on Bimaterial Interfaces: Part I—Small Scale Yielding

1988 ◽  
Vol 55 (2) ◽  
pp. 299-316 ◽  
Author(s):  
C. F. Shih ◽  
R. J. Asaro
Keyword(s):  
Phase Angle ◽  
Mixed Mode ◽  
Numerical Solutions ◽  
Crack Tip ◽  
Small Scale ◽  
Plastic Behavior ◽  
Small Scale Yielding ◽  
Elastic Plastic ◽  
Crack Problems ◽  
Scale Yielding

Full-field numerical solutions for a crack which lies along the interface of an elastic-plastic medium and a rigid substrate are presented. The solutions are obtained using a small strain version of the J2-deformation theory with power-law strain hardening. In the present article, results for loading causing only small scale yielding at the crack tip are described; in subsequent articles the mathematical structure of the crack-tip fields under small scale yielding and results for contained yielding and fully plastic behavior will be presented. We find that although the near-tip fields do not appear to have a separable singular form, of the HRR-type fields as in homogeneous media, they do, however, bear interesting similarities to certain mixed-mode HRR fields. Under small scale yielding, where the remote elastic fields are specified by a complex stress-concentration vector Q = |Q|eiφ with φ being the phase angle between the two in-plane stress modes, we find that the plastic fields are members of a family parameterized by a new phase angle ξ, ≡ φ + εln(QQ/σ02L), and the fields nearly scale with the well-defined energy release rate as evaluated by the J-integral. Here σ0 is the reference yield stress and L is the total crack length (or a relevant length of the crack geometry). Numerical procedures appropriate for solving a general class of interface crack problems are also presented. A description of a numerical method for extracting the mixed mode stress intensities for cracks at interfaces and in homogeneous isotropic or anisotropic media, is included.

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