• International Journal of Railway
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• 제2권4호
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• pp.131-138
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• 2009

Static tensile and fatigue tests were conducted using tensile-shear specimens to evaluate the fatigue strength of a SPCC sheet clinch joint. The maximum tensile strength of the specimen produced at the optimal punching force was 1750 kN. The fatigue endurance limit (=760 N) approached 43% of the maximum tensile load (=1750 N) at a load ratio of 0.1, suggesting that the fatigue limit is approximately half of the value of the maximum tensile strength. The FEM analysis showed that at the fatigue endurance limit, the maximum von-Mises stress of 373 MPa is very close to the ultimate tensile strength of the SPCC sheet (=382 MPa).

• Journal of Welding and Joining
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• 제35권2호
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• pp.23-29
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• 2017

Mechanical properties and hardness distributions in arc brazed joints of Dual phase steel using Cu-Al insert metal were investigated. The maximum tensile shear load was 10.4kN at the highest brazing current. It was about 54% compared to tensile load of base metal. This joint efficiency is higher than that of joint of DP steel using Cu-based filler metals which are Cu-Si, Cu-Sn. Fracture positions can be divided into two types. Crack initiation commonly occurred at three point junction among upper sheet, lower sheet and the fusion zone. However crack propagations were different with increasing the brazing current. In case of the lower current, it instantaneously propagated along with the interface between fusion zone and upper base material. On the other hand, in case of higher current, a crack propagation occurred through fusion zone. When the brazing current is low (60, 70A), the interface shape is flat type. However the interface shape is rough type, when the brazing current is high (80A). It is thought that the interface shapes were the reason why the crack propagations were different with brazing current. The interface was the intermetallic compounds which consisted of $(Fe,Al)_{0.85}Cu_{0.15}$ IMC formed by crystallization at $1200^{\circ}C$during cooling. Therefore the maximum tensile shear load and the fracture behavior were determined by a interface shape and effective sheet thickness of the fracture position.

• Journal of Welding and Joining
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• 제13권2호
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• pp.60-67
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• 1995

The factors affecting on the fatigue strength of spot_welded specimens have been studied. The influence of initial overloads on the fatigue life of spot_welded tensile_shear specimens is investigated by considering fatigue crack initiation and crack propagation. The change of strain range and the influence of initial overload are correlated on the basis ol strain results. The results of this study are as follows. l) The initial absolute strain range decreased with initial overloads increase, and absolute strain range decreased before transformation of waveform of strain, but increased after transformation of waveform of strain. 2) In case of subsequent point of inflection of offset strain, the increment of this strain decreased with initial overload increase. 3) As initial overloads increase, the deformation behavior of spot welded parts is restricted after overloading.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.485-488
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• 2000

In this study, the fatigue characteristic of spot weld specimen was studied by using the various specimen. The specimen types were tensile shear specimen welded one spot and two spot, and cross tension. The tensile tests and fatigue tests were executed to know the mechanical properties under static and fatigue load condition. In addition, the relationship was illustrated by finite element method.

• Journal of Welding and Joining
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• 제26권6호
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• pp.81-91
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• 2008

The weldability of resistance spot welding of TRIP1180 steels for automobile components investigated enhance in order to achieve understanding of weld fracture during tensile-shear strength (TSS) test. The main failure modes for spot welds of TRIP1180 steels were nugget pullout and interfacial fracture. The peak load to cause a weld interfacial failure was found to be related to fracture toughness of the weld and the weld diameter. Although interfacial fracture occurred in the spot welded samples, the load-carrying capacity of the weld was high and not significantly affected by the fracture mode. Substantial part of the weld exhibits the characteristic dimple (or elongated dimple) fractures on interfacial fractured surface also, dimple fracture areas were drawmatically increased with heat input which is propotional to the applied weld current. In spite of the high hardness values associated with the martensite microstructures due to high cooling rate. The high load-carrying ability of the weld is directly associated with the area of ductile fracture occurred in weld. Therefore, the judgment of the quality of resistance spot welds in TRIP1180 steels, the load-carrying capacity of the weld should be considered as an important factor than fracture mode.

• 대한금속재료학회지
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• 제46권10호
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• pp.672-682
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• 2008

The resistance spot welding of TRIP590 steels was investigated to enhance understanding of weld fracture during tensile-shear strength (TSS) test. The main failure modes for spot welds of TRIP590 steels were nugget pullout and interfacial fracture. The peak load to cause a weld interfacial failure was found to be related to fracture toughness of the weld and the weld diameter. Although interfacial fracture occurred in the samples, the load carrying capacity of the weld was high and not significantly affected by the fracture mode. Substantial part of the weld exhibits the characteristic dimple (or elongated dimple) fractures on interfacial fractured surface, in spite of the high hardness values associated with the martensite microstructures. The high load-bearing ability of the weld is directly associated with the area of ductile fracture occurred in weld. Therefore, the judgment of the quality of resistance spot welds in TRIP590 steels, the load carrying capacity of the weld should be considered as an important factor than fracture mode.

• 한국안전학회지
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• 제26권4호
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• pp.1-6
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• 2011

New methods for joining sheet of metal are being sought. One of the most promising methods is MPJ (mechanical press joining). It has been used in thin metal work because of its simple process and relative advantages over other methods, as it requires no fasteners such as bolts or rivets, consumes less energy than welding, and produces less ecological problems than adhesive methods. In this study, the joining process and static behavior of single overlap joints has been investigated. During fixed die type joining process for SPCC plates, the optimal applied punching force was found. The maximum tensile-shear strength of the specimen produced at the optimal punching force was 1.75 kN. The FEM analysis result on the tensile-shear specimen showed the maximum von-Mises stress of 373 MPa under the applied load of 1.7 kN, which is very close to the maximum tensile strength of the SPCC sheet(= 382 MPa). This suggests that the FEM analysis is capable of predicting the maximum tensile load of the joint.

• 대한조선학회논문집
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• 제55권3호
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• pp.205-214
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• 2018

This paper deals with the experimental study on the hygrothermal ageing effect to the strength of Carbon Fiber Reinforced Plastics (CFRP) materials for marine leisure boat manufactured by vacuum assisted resin infusion method. The experiments performed consist of tensile, flexural and shear tests according to American Society for Testing and Materials (ASTM) and Korean Industrial Standards (KS) test methods. Test coupons are varied from uni-directional(UD, $0^{\circ}$, $90^{\circ}$), Bi-Directional (BD), and Double-Bias (DB) carbon fiber fabrics in conjunction with epoxy resin. The results of tensile test show that tensile strength reduces significantly while not the same degree of reduction is observed for elasticity modulus with respect to the existence of hygrothermal ageing effect. This implies that the tensile strain induced from external load holds steady values but ultimate strength values change widely under hygrothermal ageing effect. In case of the flexural test, $0^{\circ}$ UD shows more strength reduction than $90^{\circ}$ UD while BD has reduced values in both flexural strength and elasticity modulus under hygrothermal ageing effect. It is learned that the bending strain induced from external load and ultimate strength values are reduced with respect to hygrothermal ageing effect. Shear test performed only on DB materials, and the results show marginal reduction in ultimate strength and moderate reduction in elasticity modulus. This means that the shear strain varies more than ultimate shear strength with respect to hygrothermal ageing effect. The experiment conducted in this paper clearly demonstrates the differences in material properties of the CFRP for the consideration of hygrothermal ageing effect. Findings obtained from this experimental study can serve as a fundamental input data for the realistic structural responses of marine leisure boat built in CFRP materials.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.709-712
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• 1999

This paper was aimed to investigate the shear strengthening effect of the pre-loaded reinforced concrete beams strengthened by carbon fiber sheet (CFS). Main tet parameters was the magnitude of pre-loading at the time of the retrofit and the strengthening method of carbon fiber sheet. A series of nine specimens was tested to evaluate the corresponding effect of each parameters such as maximum load capacity, load-deflection relationship, and failure mode. The results of this study showed that the failure mode is bonding failure between the concrete and the CFS before the tensile failure strain of the CFS is reached.

• 기술사
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• 제19권4호
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• pp.5-10
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• 1986

On SWS 41 Plates jointed by the F11T M 20 high strength bolts the study on stress behavior and safety degree until rupture in static tensile tests were performed. By these results, in case of no clamping force stress concentration was extremed for strain of about 10% higher ratio. Elastic strain occurred to change of test specimens depth by the load and plastic strain occurred to local minute sleep after elastic strain. compared shear stress with tension stress from the fracture load it was showned lower values than the maximum shear stress theory and stress strain energy theory.