The Effect of the Size and Position of the Crack on the Normalized Stress Intensity Factor

In this work, finite element method was used to determine the normalized stress intensity factors for different configurations. For this, a 2-D numerical analysis with elastic behavior was undertaken in pure I mode. This simulation was carried out using a numerical calculation code. On the basis of the numerical results obtained from the different models treated, there is a good correlation between the nodal displacement extrapolation method (DEM) and the energy method based on the Rice integral (J) to evaluate the normalized stress intensity factors and this for different crack lengths. For each configuration, the increase in the crack size causes an amplification of normalized intensity stresses fators.

A Generation of Special Triangular Boundary Element Shape Functions for 3D Crack Problems

This paper focuses on tackling the two drawbacks of the dual boundary element method (DBEM) when solving crack problems with a discontinuous triangular element: low accuracy of the calculation of integrals with singularity and crack front element must be utilized to model the square-root property of displacement. In order to calculate the integrals with higher order singularity, the triangular elements are segmented into several subregions which consist of subtriangles and subpolygons. The singular integrals in those subtriangles are handled by the singularity subtraction technique in the integration space and can be regularized and accurately calculated. For the nearly singular integrals in those subpolygons, the element subdivision technique is employed to improve the calculation accuracy. In addition, considering the location of the crack front in the element, special crack front elements are constructed based on a 6-node discontinuous triangular element, in which the displacement extrapolation method is introduced to obtain the stress intensity factors (SIFs) without consideration of orthogonalization of the crack front mesh. Several numerical results are investigated to fully verify the validation of the presented approach.

Calculation of Stress Intensity Factor using Displacement Extrapolation Method in Peridynamic Framework

ABSTRACTThis paper introduces a new approach to calculate stress intensity factors based on a combination of Displacement Extrapolation Method and Peridynamic Theory. After obtaining the displacement field from Peridynamic Theory, by appropriately selecting nodes at the crack tip region and their displacements yield stress intensity factors at the crack tips. To demonstrate the capability of the proposed approach, three different benchmark problems are considered including plate with a central crack, plate with an edge crack and plate with a slanted crack. Results evaluated from the current approach are compared against analytical and finite element analysis results, and good agreement is obtained between three different approaches. This shows that coupled Displacement Extrapolation Method and Peridynamic Theory approach can be an alternative method to calculate stress intensity factors.

Theoretical study for estimation of the dynamic stress intensity factor from results of an experimental measurement

The aim of this contribution is a theoretical study for the estimation of the dynamic stress intensity factor (DSIF) using results from an experimental measurement. Using optical methods, it is possible to determine individual displacements of crack surfaces in multiple distances from the crack tip. Based on the theoretical distribution of displacements in the crack front, the DSIF can be estimated using the displacement extrapolation method at each time step. The main motivation for this methodology is the difficulty of estimation DSIF in real structures. The described approach is consequently compared with conventional numerical methods and the applicability is evaluated.

Finite Element Modeling of Intermetallic Compound (IMC) Solder Joints Fracture: Part A

Solder joints failure due to thermal loads and mechanical loads is a significant reliability concern in electronic devices. From literatures, little attention is paid to the development of methods on predicting fracture behavior of solder joint under mixed-mode loading. This paper presents a finite element modeling of intermetallic compounds solder joints failure based on displacement extrapolation method (DEM). Conceptual study on single edge crack on intermetallic IMC solder joints is presented.

Finite Element Modeling of Intermetallic Compound (IMC) Solder Joints Fracture: Part B

Solder joints are exposed to drop impact, vibration loading, bending, and twisting of PCBs. Study on this matter will lead to prediction of fracture load, prevalent fracture mode, exact joint interconnect size and life of joints under brittle and fatigue failure. This paper presents a finite element modeling of intermetallic compounds solder joints failure based on displacement extrapolation method. Based on conceptual FE model of intermetallic IMC solder joints, this paper present the full model of IMC model for intermetallic Mode I and Mode II fracture prediction.