Relationship Between Singularity Strength Factors and Practical Bonding Strength of Ceramic to Metal Joint

2010 ◽  
Author(s):  
Masayoshi Tateno ◽  
Hiroki Morikawa
Keyword(s):  
Stress Intensity ◽  
Bonding Strength ◽  
Wedge Angle ◽  
Stress Singularity ◽  
Interface Shape ◽  
Intensity Factors ◽  
Electric Discharge Machining ◽  
Metal Joint ◽  
The Relationship ◽  
Interface Geometry

This study correlates the stress intensity factors (Kii, Kpaii), the order of the stress singularity p-1, and the practical bonding strength of ceramic to metal joints with arbitrary interface geometry. First, in order to describe the stress behavior of TiB2 to Ni joints bonded at 1173K, the stress singularity factors (Kii, Kpaii, p-1) were theoretically derived for wedge angles of φ1:30°<φ1<150°. Secondly, the dependences of the singularity factors on the wedge angle φ1 were compared with experimental results using the same wedge angles on TiB2 to Ni joints with interface convexity or concavity produced by Electric Discharge Machining (EDM). In order to obtain the highest strength joints, the optimum interface shape is determined using the relationship between the singularity factors.

Effects of Interface Wedge Angle in Metal Side on Bonding Strength in Ceramic to Metal Joint

2011 ◽  
Author(s):  
Masayoshi Tateno ◽  
Eiichirou Yokoi
Keyword(s):  
Free Surface ◽  
High Temperature ◽  
Bonding Strength ◽  
Wedge Angle ◽  
Fracture Pattern ◽  
Interface Conditions ◽  
Interface Shape ◽  
Electric Discharge Machining ◽  
Metal Joint ◽  
Wire Electric Discharge Machining

This study was performed to clarify dependences of bonding strength on the interface wedge angle in the metal side of ceramic-to-metal joint. Each plate Si3N4 and Ni used for this experiment is produced by wire electric discharge machining. The geometric interface shape at the edge of the interface is characterized by wedge angle on both side of the ceramic and metal defined as a configuration angle between the free surface of each material and the interface. As the wedge angle of Si3N4 is a right angle, the wedge angle of Ni is set from 30° to 180°. Joint specimens were bonded at high temperature using braze metal of 0.05mm thickness under vacuum and cooled slowly. The tensile bonding strength of the ceramic-to-metal joint was evaluated to determine the optimum interface shape. The highest bonding strength appeared under identical interface conditions where the fracture pattern changed. This study provided a useful geometric interface shape to improve the tensile bonding strength of ceramic-to-metal joint.

Effect of Interface Wedge Angle in Ceramic Side on Tensile Bonding Strength in Ceramic to Metal Joint

2009 ◽  
Author(s):  
Masayoshi Tateno ◽  
Hiroki Morikawa ◽  
Kunio Kokubo
Keyword(s):  
Free Surface ◽  
Bonding Strength ◽  
Bonding Temperature ◽  
Wedge Angle ◽  
Fracture Pattern ◽  
Interface Conditions ◽  
Interface Shape ◽  
Electric Discharge Machining ◽  
Side Plate ◽  
Metal Joint

This study was performed to clarify the dependence of ceramic-to-metal joint bonding strength on the interface wedge angle on the ceramic side. Plate Si3N4-to-Ni joints with a plane interface were produced by electric discharge machining. The geometric interface shape at the edge of the interface is characterized by wedge angle on both sides of the ceramic and metal defined as a configuration angle between the free surface of each material and the interface. As the wedge angle of Ni is a right angle, the wedge angle of Si3N4 is set from 30° to 180°. Joints were bonded at high temperature using thin braze metal under vacuum and cooled slowly. The tensile bonding strength of the ceramic-to-metal joint was evaluated to determine the optimum interface shape. The highest bonding strength appeared under identical interface conditions where the fracture pattern changed. The optimum wedge angle to obtain the greatest bonding strength appears to depend on bonding temperature. This study provided a useful geometric interface shape to improve the tensile bonding strength of ceramic-to-metal joints.

Dependence of Bonding Strength of Ceramic to Metal Joint on Interface Wedge Angle in Metal Side

2012 ◽  
Author(s):  
Masayoshi Tateno ◽  
Eiichiro Yokoi
Keyword(s):  
Bonding Strength ◽  
Bonding Temperature ◽  
Wedge Angle ◽  
Fracture Pattern ◽  
Interface Condition ◽  
Geometrical Shape ◽  
Electric Discharge Machining ◽  
Bonded Materials ◽  
Edge Angle ◽  
Metal Joint

The focus of this study is to clarify a dependence of bonding strength of ceramic to metal joint on interface wedge angle in metal side. Each plate Si3N4-to-Cu or Ni joint with plane interface is produced by electric discharge machining. Geometrical shape at the edge of the interface is characterized by wedge angle defined as a configuration angle between free surface of each material and the interface. As the wedge angle of Si3N4 is right angle, the wedge angle of metal is set over from 30° to 180°. Each joint is bonded at high temperature by using thin braze metal under vacuum and slowly cooled. Tensile bonding strength of the joint is evaluated. Result shows that decrease of the wedge angle of metal side from right angle improves the bonding strength since it decreases the residual stress near edge of the interface on ceramic side. The highest bonding strength appears at the identical interface condition where fracture pattern changes. It appears that optimum edge angle for obtaining the highest bonding strength depends on bonding temperature and combination of bonded materials. This paper provides a useful geometrical interface shape to improve tensile bonding strength of ceramic to metal joint.

A Coupled SBFEM-FEM Approach for Evaluating Stress Intensity Factors

2013 ◽  
Vol 353-356 ◽  
pp. 3369-3377 ◽  
Author(s):  
Ming Guang Shi ◽  
Chong Ming Song ◽  
Hong Zhong ◽  
Yan Jie Xu ◽  
Chu Han Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Complex Geometry ◽  
Stress Singularity ◽  
Intensity Factors ◽  
Finite Element Software ◽  
Scaled Boundary Finite Element ◽  
Element Method

A coupled method between the Scaled Boundary Finite Element Method (SBFEM) and Finite Element Method (FEM) for evaluating the Stress Intensity Factors (SIFs) is presented and achieved on the platform of the commercial finite element software ABAQUS by using Python as the programming language. Automatic transformation of the finite elements around a singular point to a scaled boundary finite element subdomain is realized. This method combines the high accuracy of the SBFEM in computing the SIFs with the ability to handle material nonlinearity as well as powerful mesh generation and post processing ability of commercial FEM software. The validity and accuracy of the method is verified by analysis of several benchmark problems. The coupled algorithm shows a good converging performance, and with minimum additional treatment can be able to handle more problems that cannot be solved by either SBFEM or FEM itself. For fracture problems, it proposes an efficient way to represent stress singularity for problems with complex geometry, loading condition or certain nonlinearity.

Mixed Mode Stress Singularities in Anisotropic Composites

1999 ◽  
Author(s):  
Wan-Lee Yin
Keyword(s):  
Stress Intensity ◽  
Asymptotic Solution ◽  
Stress Intensity Factors ◽  
Stress Singularity ◽  
Free Edge ◽  
Complex Conjugate ◽  
Circular Path ◽  
Intensity Factors ◽  
Element Analysis ◽  
Anisotropic Elastic

Abstract Multi-material wedges composed of fully anisotropic elastic sectors generally show intrinsic coupling of the anti-plane and in-plane modes of deformation. Each anisotropic sector has three complex conjugate pairs of material eigensolutions whose form of expression depends on five distinct types of anisotropic materials. Continuity of the displacements and the tractions across the sector interfaces and the traction-free conditions on two exterior boundary edges determine an infinite sequence of eigenvalues and eigensolutions of the multi-material wedge. These eigensolutions are linearly combined to match the traction-boundary data (generated by global finite element analysis of the structure) on a circular path encircling the singularity. The analysis method is applied to a bimaterial wedge near the free edge of a four-layer angle-ply laminate, and to a trimaterial wedge surrounding the tip of an embedded oblique crack in a three-layer composite. Under a uniform temperature load, the elasticity solution based on the eigenseries yields interfacial stresses that are significantly different from the asymptotic solution (given by the first term of the eigenseries), even as the distance from the singularity decreases to subatomic scales. Similar observations have been found previously for isotropic and orthotropic multi-material wedges. This raises serious questions with regard to characterizing the criticality of stress singularity exclusively in terms of the asymptotic solution and the associated stress intensity factors or generalized stress intensity factors.

Structural Design of the Geometrical Shape of Interfaces in Bonded Dissimilar Materials Based on Theoretical Elastic Analysis

1999 ◽  
Vol 586 ◽  
Author(s):  
Masayoshi Tateno ◽  
Yasushi Fukuzawa ◽  
Shigeru Nagasawa ◽  
Hiroshi Sakuta
Keyword(s):  
Stress Distribution ◽  
Structural Design ◽  
Bonding Strength ◽  
Stress Singularity ◽  
Dissimilar Materials ◽  
Correlation Factor ◽  
Geometrical Shape ◽  
Elastoplastic Behavior ◽  
Secant Stiffness ◽  
The Relationship

ABSTRACTIn order to evaluate the practical strength of a joint and its fracture mode, it is important to find the stress distribution near the edge of the interface by analyses of strength and fracture. The index of stress singularity based on theoretical analysis is a useful tool to indicate the stress distribution.In this paper, investigations on the evaluation of the practical strength of bonded dissimilar materials based on the stress singularity are carried out. The secant stiffness module, which was used for plastics analysis, was applied to the evaluation of thermal elastoplastic behavior near the interface. Spherical conditions of the interface shape were used for the evaluation of stress behavior and the experiment of bonding strength. The relationship between the index of stress singularity, λ, and the practical strength of the bonded TiB2-Ni system was investigated by comparing theoretical λ, which was determined by substituting the secant stiffness module into Bogy's eigenequation, with the practical strength in the edge angle of the interface between 60° and 90° The correlation factor of the relationship between λ and the practical bonding strength of the TiB2-Ni system was found positive. These results show that the structural design of a geometrical interface which is getting a higher strength joint based on the index of stress singularity is verified experimentally.

Transient Stress Intensity Factors of an Interfacial Crack Between Two Dissimilar Anisotropic Half-Spaces, Part 2: Fully Anisotropic Materials

1984 ◽  
Vol 51 (4) ◽  
pp. 780-786 ◽  
Author(s):  
A.-Y. Kuo
Keyword(s):  
Stress Intensity ◽  
Integral Equations ◽  
Singular Integral ◽  
Stress Intensity Factors ◽  
Jacobi Polynomials ◽  
Mathematical Problem ◽  
Stress Singularity ◽  
Interfacial Crack ◽  
Singular Integral Equations ◽  
Intensity Factors

Dynamic stress intensity factors for an interfacial crack between two dissimilar elastic, fully anisotropic media are studied. The mathematical problem is reduced to three coupled singular integral equations. Using Jacobi polynomials, solutions to the singular integral equations are obtained numerically. The orders of stress singularity and stress intensity factors of an interfacial crack in a (θ(1)/θ(2)) composite solid agree well with the finite element solutions.

Relation between Stress Intensity Factor of a Small Edge Interface Crack and Intensity of Free-Edge Stress Singularity of Bonded Dissimilar Materials

2004 ◽  
Vol 261-263 ◽  
pp. 351-356
Author(s):  
Seiji Ioka ◽  
Shiro Kubo
Keyword(s):  
Stress Intensity Factor ◽  
Free Surface ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Edge Crack ◽  
Stress Singularity ◽  
Dissimilar Materials ◽  
Free Edge ◽  
Edge Stress ◽  
The Relationship

When two materials are bonded, the free-edge stress singularity usually develops near the intersection of the interface and the free-surface. Fracture in bonded dissimilar materials may therefore occur from an interface crack which develops at the intersection of interface and free-surface. Free-edge stress singularity is very important in the evaluation of strength of bonded dissimilar materials. In this study, the relationship between the stress intensity factor of a small edge crack on interface of bonded dissimilar materials and the intensity of free-edge stress singularity of bonded dissimilar materials with no crack under external mechanical loading was investigated numerically by using the boundary element method. The relationship was also investigated theoretically by using the principle of superposition. The results of numerical analyses were compared with those of theoretical analyses. It was found that stress intensity factors of small edge crack on interface K1 and K2 were proportional to the intensity of free-edge stress singularity of bonded dissimilar materials Kσ without crack irrespective of the combination of materials. The numerically determined proportional coefficient between K1 and Kσ agreed well with the theoretical one, and was not affected by crack length when proper normalizations were applied. From these results, it is suggested that stress intensity factor of small edge crack on interface can be used as a strength criterion of interface of bonded dissimilar materials.

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