Stress singularity analysis around the singular point on the stress singularity line in three-dimensional joints

2005 ◽  
Vol 42 (11-12) ◽  
pp. 3059-3074 ◽  
Author(s):  
Monchai Prukvilailert ◽  
Hideo Koguchi
Keyword(s):  
Singular Point ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Singularity Analysis ◽  
Singularity Line

Three-Dimensional Stress Singularity Analysis Around the Solder Joints in Electronic Packaging Using Eigen Analysis

2003 ◽  
Author(s):  
Monchai Prukvilailert ◽  
Hideo Koguchi
Keyword(s):  
Mechanical Properties ◽  
Electronic Packaging ◽  
Flip Chip ◽  
Solder Bump ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Dissimilar Materials ◽  
Singularity Analysis ◽  
Contact Angles ◽  
Eigen Analysis

Electronic packaging has several kinds of joint structures of metal, ceramic and polymer. It is well known that the stress singularity occurs at the vertex of joint where the dissimilar materials are bonded together. In this paper, the model in the first analysis is an electronic package using surface mount technology (SMT), the order of stress singularity is investigated, when the mechanical properties of solder, adhesive and resin vary for several values of contact angles between the solder with the chip and with a Cu land. Furthermore, the model in the second analysis is a Flip-Chip-on-Board packaging (FCOB), in which the order of stress singularity at the solder bump is investigated varying the mechanical properties of solder, underfill and the contact angle between the solder bump with a Cu track. After that, the displacement and stress fields for several values of the order of stress singularity are calculated by solving an eigen equation.

A Conservative Integral for Calculating Intensities of Singularities at 3D Piezoelectric Bonded Joints

2015 ◽  
Author(s):  
Chonlada Luangarpa ◽  
Hideo Koguchi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Singular Point ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Bonded Joints ◽  
Conservative Integral ◽  
Dimensional Finite Element ◽  
Refined Meshes ◽  
Three Dimensional Finite Element

In the present study, a conservative integral based on the Betti reciprocal principle is extended for calculating the intensities of singularities at a vertex of the interface in three-dimensional piezoelectric bonded joints. Eigenanalysis formulated using a three-dimensional finite element method (FEM) is used to calculate the order of stress singularity, angular variables of mechanical displacements, stresses, electric displacements and electric potential. A model with applied both mechanical and electrical loading conditions are considered. In order to investigate the influence of mesh refinement and integral area on the accuracy of the results, models with various element sizes and integral areas are used. The results are compared with those obtained from conventional FEM, in which using extremely refined meshes near the singular point.

Evaluation of Joining Strength of Silicon-Resin Interface at a Vertex in 3D Joint Structure

2011 ◽  
Author(s):  
Hideo Koguchi ◽  
Kazuhisa Hoshi
Keyword(s):  
Stress Distribution ◽  
Boundary Element ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Singularity Analysis ◽  
Eigenvalue Analysis ◽  
Singular Stress ◽  
Two Phase ◽  
Joining Strength ◽  
Element Method

Portable electric devices such as mobile phone and portable music player become compact and improve their performance. High-density packaging technology such as CSP (Chip Size Package) and Stacked-CSP is used for improving the performance of devices. CSP has a bonded structure composed of materials with different properties. A mismatch of material properties may cause stress singularity, which lead to the failure of bonding part in structures. In the present paper, stress analysis using boundary element method and an eigenvalue analysis using finite element method are used for evaluating the intensity of singularity at a vertex in three-dimensional joints. Three-dimensional boundary element program based on the fundamental solution for two-phase isotropic materials is used for calculating the stress distribution in a three-dimensional joint. Angular function in the singular stress field at the vertex in the three-dimensional joint is calculated using eigen vector determined from the eigenvalue analysis. The joining strength of interface in several kinds of sillicon-resin specimen with different triangular bonding areas is investigated analytically and experimentally. Experiment for debonding the interface in the joints is firstly carried out. Stress singularity analysis for the three-dimensional joints subjected to an external force for debonding the joints is secondly conducted. Combining results of the experiment and the analysis yields a final stress distribution for evaluating the strength of interface. Finally, a relationship of force for delamination in joints with different bonding areas is derived, and a critical value of the 3D intensity of singularity is determined.

Evaluation of Joining Strength of Silicon-Resin Interface at a Vertex in a Three-Dimensional Joint Structure

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Hideo Koguchi ◽  
Kazuhisa Hoshi
Keyword(s):  
Stress Distribution ◽  
Boundary Element ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Singularity Analysis ◽  
Eigenvalue Analysis ◽  
Singular Stress ◽  
Two Phase ◽  
Joining Strength ◽  
Element Method

Portable electric devices such as mobile phones and portable music players have become compact and improved their performance. High-density packaging technology such as chip size package (CSP) and stacked-CSP is used for improving the performance of devices. CSP has a bonded structure composed of materials with different properties. A mismatch of material properties may cause a stress singularity, which leads to the failure of the bonding part in structures. In the present paper, stress analysis using the boundary element method and an eigenvalue analysis using the finite element method are used for evaluating the intensity of a singularity at a vertex in three-dimensional joints. A three-dimensional boundary element program based on the fundamental solution for two-phase isotropic materials is used for calculating the stress distribution in a three-dimensional joint. Angular function in the singular stress field at the vertex in the three-dimensional joint is calculated using an eigenvector determined from the eigenvalue analysis. The joining strength of interface in several kinds of sillicon-resin specimen with different triangular bonding areas is investigated analytically and experimentally. An experiment for debonding the interface in the joints is firstly carried out. Stress singularity analysis for the three-dimensional joints subjected to an external force for debonding the joints is secondly conducted. Combining results of the experiment and the analysis yields a final stress distribution for evaluating the strength of interface. Finally, a relationship of force for delamination in joints with different bonding areas is derived, and a critical value of the 3D intensity of the singularity is determined.

Optimization of the Wrist Pin End of an Automobile Engine Connecting Rod With an Interference Fit

1990 ◽  
Vol 112 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Vijay Sarihan ◽  
Ji Oh Song
Keyword(s):  
Finite Element ◽  
Optimum Design ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Design Strategy ◽  
Structural Components ◽  
Connecting Rod ◽  
Fem Model ◽  
Automobile Engine ◽  
Interference Fit

Current design procedures for complicated three-dimensional structural components with component interactions may not necessarily result in optimum designs. The wrist pin end design of the connecting rod with an interference fit is governed by the stress singularity in the region where the wrist pin breaks contact with the connecting rod. Similar problems occur in a wide variety of structural components which involve interference fits. For a better understanding of the problems associated with obtaining optimum designs for this important class of structural interaction only the design problems associated with the wrist pin end of the rod are addressed in this study. This paper demonstrates a procedure for designing a functional and minimum weight wrist pin end of an automobile engine connecting rod with an interference fit wrist pin. Current procedures for Finite Element Method (FEM) model generation in complicated three-dimensional components are very time consuming especially in the presence of stress singularities. Furthermore the iterative nature of the design process makes the process of developing an optimum design very expensive. This design procedure uses a generic modeler to generate the FEM model based on the values of the design variables. It uses the NASTRAN finite element program for structural analysis. A stress concentration factor approach is used to obtain realistic stresses in the region of the stress singularity. For optimization, the approximate optimization strategy in the COPES/CONMIN program is used to generate an approximate design surface, determine the design sensitivities for constrained function minimization and obtain the optimum design. This proposed design strategy is fully automated and requires only an initial design to generate the optimum design. It does not require analysis code modifications to compute the design sensitivities and requires very few costly NASTRAN analyses. The connecting rod design problem was solved as an eight design variable problem with five constraints. A weight reduction of nearly 27 percent was achieved over an existing design and required only thirteen NASTRAN analyses. It is felt that this design strategy can be effectively used in an engineering environment to generate optimum designs of complicated three-dimensional components.

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