• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.58-68
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• 1998

Advantages of adhesively bonded joints and techniques of weight reduction have led to increasing use of structural adhesives such as LSI(large scale integration) package, automobile, aircraft in the various industries. In spite of such wide applications of adhesively bonded joints, the evaluation method of bonding strength has not been established. Stress singularity occurs at the interface edges of adhesively bonded joints and it is required to analyze it. In this paper, the stress singularity using 2-dimensional elastic boundary element method (BEM) with the changes of the lap length and adhesive for single lap joint was analyzed, and experiments of strength evaluation were carried out. As the results, the evaluating method of bonding strength considering stress singularity at interface edges of adhesively bonded joints and stress intensity factor of interface crack have been proposed in static and fatigue test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.49-54
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• 1993

This paper discusses the reliability of solder joints of electronic devices on printed circuit board. Solder application is usually done by screen printing method for the bonding between outer leads of devices and thick film(Ag/Pd) pattern on Hybrid IC as wel1 as Cu lands on PCB. As result of thermal stresses generated at the solder joints due to the differences of thermal expansion coefficients between packge body and PCB, Micro cracking often occurs due to thermal fatigue failure at solder joints. The initiation and the propagate of solder joint crack depends on the environmental conditions, such as storage temperature and thermal cycling. The principal mechanisms of the cracking pheno- mana are the formation of kirkendal void caused by the differences in diffusion rate of materials, ant the thermal fatigue effect due to the differences of thermal expansion coefficient between package body and PCB. Finally, This paper experimentally shows a way to supress solder joints cracks by using low-${\alpha}$ PCB and the packages with thin lead frame, and investigates the phenomena of diffusion near the bonding interfaces.

• Steel and Composite Structures
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• v.51 no.1
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• pp.53-61
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• 2024

Aluminum foams sandwich panel (AFSP) has been used in engineering field, where cyclic loading is used in most of the applications. In this paper, the fatigue life of AFSP prepared by the bonding method was investigated through a three-point bending test. The mathematical statistics method was used to analyze the influence of different plate thicknesses and core densities on the bending fatigue life. The macroscopic fatigue failure modes and damage mechanisms were observed by scanning electron microscopy (SEM). The results indicate that panel thickness and core layer density have a significant influence on the bending fatigue life of AFSP and their dispersion. The damage mechanism of fatigue failure to cells in aluminum foam is that the initial fatigue crack begins the cell wall, the thinnest position of the cell wall or the intersection of the cell wall and the cell ridge, where stress concentrations are more likely to occur. The fatigue failure of aluminum foam core usually starts from the semi-closed unit of the lower layer, and the fatigue crack propagates layer by layer along the direction of the maximum shear stress. The results can provide a reference for the practical engineering design and application of AFSP.

• Journal of Welding and Joining
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• v.29 no.1
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• pp.46-51
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• 2011

TSV technology raises several reliability concerns particularly caused by thermally induced stress. In traditional package, the thermo-mechanical failure mostly occurs as a result of the damage in the solder joint. In TSV technology, however, the driving failure may be TSV interconnects. In this study, the thermomechanical reliability of TSV technology is investigated using finite element method. Thermal stress and thermal fatigue phenomenon caused by repetitive temperature cycling are analyzed, and possible failure locations are discussed. In particular, the effects of via size, via pitch and bonding pad on thermo-mechanical reliability are investigated. The plastic strain generally increases with via size increases. Therefore, expected thermal fatigue life also increase as the via size decreases. However, the small via shows the higher von Mises stress. This means that smaller vias are not always safe despite their longer life expectancy. Therefore careful design consideration of via size and pitch is required for reliability improvement. Also the bonding pad design is important for enhancing the reliability of TSV structure.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.260-263
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• 2005

Fatigue fracture behavior of a hybrid joint between side-panel and under-frame by riveting and adhesive bonding has been evaluated. Two kinds of joint specimens based on real geometry were fabricated for shearing test as well as bending test. Static and cyclic loadings were used for fatigue assessment. Fatigue fracture results obtained by such experiments were reflected in modifications of design parameters of the hybrid joint.

• Journal of Welding and Joining
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• v.3 no.1
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• pp.32-39
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• 1985

Fatigue lives of C.T. specimens containing the holes or the holes filled with other materials are investiated by experimental and analytical methods. The results of the study are as follows; 1) The fatigue lives are in the order of E'/E > 1, E'/E = 1, and E'/E < 1, where E' is the Young's modulus of other materials filling holes and E is that of matrix. 2) The fatigue life of E'/E = 0 is shortest than thost of E'/E > 1, E'/E = 1 and E'/E < 1. 3) The fatigue life of C.T. specimen containing the holes filled with other materials is shorter than that of matrix without holes. 4) Because of the stress concentration around the bonding boundary, crack initiates from the lower left on the boundary and propagates toward the upper right along the boundary.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.99-105
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• 2002

One of the important advantage of adhesive bonded joint can combine the different materials. The joint that bonded by structural adhesive bond must keep a large force and its strength is affected by some environmental factors such as temperature and submergence time in water. In order to advance the fatigue strength of adhesive bonded joint, mostly put a surface treatment on the surface. This study was researched the effect of air temperature, submergence time, submergence temperature and surface treatment on the fatigue strength. We found that submergence temperature has the most effect and low plasma treatment specimens have the most fatigue strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.282-285
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• 2006

This study is to examine bond strength of beam reinforced with GFRP rebar under 4-point bending test by adopting BRITISH STANDARD. The variables were made to have bonding length of 5times$(5d_b)$, 10times$(10d_b)$ and 15times$(15d_b)$ of the nominal diameter of GFRP rebar and were done to analyze the relationship between the bonding strength and the slip. In the result of the test, pull-out failure was dominant in the $5d_b$ and $10d_b$ specimen, both patterns of the pull-out failure and concrete splitting failure appeared in the $10d_b$. On the other hand, the $15d_b$ specimen showed only concrete splitting failure at the end of bonding length. Therefore, it was prove that available bonding length of the GFRP rebar under bending condition on static test is over $15d_b$ then farther research such as fatigue bending test, development of bonding model, FEM parameter study should be performed.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.89-95
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• 2008

Fatigue cracked components often needs to be repaired during service. Standard repair schemes involve strengthening the component by connecting reinforcing members by means of rivets or welding by reducing the crack-tip stress intensity factors. Recent technological advances in fiber reinforced composite materials and adhesive bonding have led to the development of efficient repair schemes. In this study, the influence of various shape parameters on fatigue crack growth in the CCT type uniform thickness plates and the thin-ta-thick type stiffened panels repaired with woven fabric type Kevlar-Epoxy composite patch are studied experimentally.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.115-118
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• 2000

The development of high-strength fibers such as boron/epoxy and carbon/epoxy and adhesives has made it possible to repair cracked metallic plates by bonding reinforcing patches to the plate over the crack. In this study, aluminum 6061-T6 alloy plates with the high strength are applied to specimens with a cracked bolt hole to study the effect of diverse patch materials on the fatigue behavior of this structure. Additionally, the observation of the effort of different patch sizes on the specimen was performed. The results shows that the patch repair can improve the static strength by about 17% and the fatigue life by 200% compared with non-repaired case. And it was also revealed that the patching method along to crack growth direction is mort efficient in cost and weight reduction.