• Journal of Welding and Joining
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• v.31 no.5
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• pp.71-76
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• 2013

The effect of zirconate having - NH functional group on the T-peel and lap shear strength of $CaCO_3$ containing structural epoxy adhesive for car body assembly was investigated. Curing behavior of epoxy adhesive samples were investigated by differential scanning calorimeter (DSC) techniques. The addition of zirconate up to 7.5 phr did not affect the curing mechanism of epoxy adhesive. While the small amount of zirconate addition less than 1.1 phr increased the cross-linking density, the excess addition of zirconate resulted in the increase of uncross-linked impurity. From the increase of T-peel and lap shear strength and the change of fracture mode from the adhesive failure to the mixed one, it was considered that the small addition of zirconate was effective in improving the adhesion strength of epoxy adhesive to the adherend and inorganic filler surfaces. The formation of uncross-linked impurity with the excess addition of zirconate was considered to decrease the joint strength by decreasing the cohesive strength of the cured epoxy.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.44-49
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• 2015

The structural epoxy adhesive used in car body assembly needs the highest level of joint mechanical strength under lap shear, T-peel and impact peel conditions. In this study, the effect of nano functionalized block copolymer addition on the impact peel strength of epoxy adhesive was investigated. DSC analysis showed that the addition of nano functionalized block copolymer did not affect the curing reaction of epoxy adhesive. From single lap shear test, it was found out that the addition of nano functionalized block copolymer slightly decreased the cohesive strength of cured adhesive layer. The addition of nano functionalized block copolymer showed beneficial effect on T-peel strength by changing the adhesive failure mode to the mixed mode. However, the addition of nano functionalized block copolymer just decreased the room temperature impact peel strength. It was considered that the addition of nano functionalized block copolymer could have effect on disturbing the crack propagation only for the case of slow strain rate.

• Journal of Welding and Joining
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• v.21 no.2
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• pp.35-41
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• 2003

Sintered alumina ceramics were joined by 2 kinds of SiO$_2$-CaO-A1$_2$O$_3$ glass solders having a similar expansivity as alumina. Wetting of glass/alumina was examined by sessile drop method. The observation of interface and bending strength related to alumina/glass/alumina systems were investigated by means of SEM/EDX and 4-point bending test. the result are summarized as follow: (1) Wetting of glass solders on alumina was good at temperatures higher than 145$0^{\circ}C$. (2) When the joining temperature wan high, diffusion and/or reactions between solder md alumina took place at the interface. These diffusions and reactions occurring at the interface greatly affected the bending strength of joining body. (3) Highest strength corresponding to 80% that of alumina was obtained by the solder of 35SiO$_2$-35CaO-30A1$_2$O$_3$(wt%) glass.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.131-135
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• 2003

The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair, But their joining strength ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, to improve joining strength. The strength and mechanical properties of the new process are discussed and compared for other joining processes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.1018-1023
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• 2012

In order to substitute and recycle the existing automobile parts for GMT-sheet, researches on the effects of GMT-sheet on the establishment of precise joining strength, joining condition that are lap length of joining part, compression ratio, and closure speed must be carried out but until now. Besides, many researches on adhesion joint had been conducted until now but no systematic research on press lap joint of GMT-sheet has been implemented until recently and the reliability of joining strength is not yet established. In press lap joining molding of GMT-sheet, tensile stress and lap joining connection efficiency was increased according to the increase of lap length L. However, as the increase of compression ratio and fiber content ratio per unit area was higher in tensile test, it has caused the deterioration of lap joining efficiency after joining molding of GMT-sheet. Clarify joining strength and lap joining efficiency during high temperature compression press lap joining molding of GMT-sheet and research data regarding to the lap length of joining part was presented. The purpose of this study is to contribute to the substitution of existing products as well as usage development in non-automobile field and also to find out precise dynamic characteristics as designing data of structures.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.519-527
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• 2005

Recently, weight reduction of vehicles has been of great interest and consequently the use of low-density materials in the automotive industry is increasing every year. However, the substitution of one material for another is not simple because it accompanies several problems, for example, weakness in the strength and stiffness and difficulty in the joining. To overcome these problems, the structure of the automobile redesigned totoally. Aluminum spaceframe is rapidly being adopted as a body structure for accommodating lightness, stiffness and strength requirement. In aluminum spaceframe manufacturing, it is often required to join aluminum tube. However, there are few suitable methods for joining aluminum tube, so that much interest has been focused on testing suitable joining methods. Joining by electromagnetic forming (EMF) can be useful method in joining aluminum tube, which offers some advantages compared with the conventional joining methods. In this paper, joining by EMF was investigated as a pre-study for applying an automotive spaceframe. Finite element simulations and strength tests were performed to analyze the influence of geometric parameters on joint strength. Based on these results, configurations of axial joint and torque joint were suggested and guidelines for designing EMF joint were established.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.58-64
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• 2013

Several joining methods involving resistance welding, laser welding, ultrasonic welding and mechanical joining are currently applied in manufacturing lithium-ion batteries. Cu and Al alloys are used for tab and bus bar materials, and laser welding characteristics for these alloys were investigated with similar and dissimilar material combinations in this study. The base materials used were Al 1050 and oxygen-free Cu 1020P alloys, and a disk laser was used with a continuous wave mode. In bead-on-plate welding of both alloys, the joint strength was higher than the strength of O tempered base material. In overlap welding, the effect of welding parameters on the tensile shear strength and bead shape was evaluated. Tensile shear strength of overlap welded joint was affected by interfacial bead width and weld defect formation. The tensile-shear specimen was fractured at the heat affected zone by selecting proper laser welding parameters.

• Journal of the Korean Society of Safety
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• v.25 no.1
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• pp.1-8
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• 2010

The tensile and fatigue experiments were conducted with tensile-shear specimens for investigating the strength of adhesive bonded and mechanical press joints of SPCC steel sheet used in the field of the automobile industry. The optimal punch press force was evaluated 50kN for combining epoxy adhesive bonding and mechanical press joining with a diameter of 8.3mm using SPCC sheet with a thickness of 0.8mm. The combining epoxy adhesive bonding and mechanical press joining exhibits the maximum tensile force of 750N. The fatigue strengths of the combination of adhesive bond and mechanical press joint and pure adhesive joint were evaluated 370N and 320N at 106cycles, respectively. These values correspond to 22% and 20% of their maximum tensile forces, respectively. However, the fatigue strength of the combination of adhesive bond and mechanical press joining was much lower than that of pure mechanical press joining.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.7-12
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• 2009

The tensile and fatigue experiments were conducted with tensile-peel specimens for investigating on strength of adhesively bonded and mechanical press joints of aluminum sheet used in the field of the automobile industry. The combining epoxy adhesive bonding and mechanical press joining exhibits an increase in joining force as a result of interaction between static forces of the two joining methods. The fatigue strength of pure adhesive joint was measured as 91% of that of the combination of adhesive bond and mechanical press joint, suggesting that the interaction between the bonding and mechanical joining was about 9%.

• Transactions of Materials Processing
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• v.25 no.1
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• pp.36-42
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• 2016

Fiber metal laminates (FMLs) are well known for improved fatigue strength, better impact resistance, superior damage tolerance and slow crack growth rate compared to traditional metallic materials. However, defects and loss of strength of a composite material can occur due to the vertical load from the punch during the joining with a dissimilar material using a conventional clinching method. In the current study, tapered-hole clinching was an alternative process used to join Al 5052 and FMLs. The tapered hole was formed in the FML before the joining. For the better understanding of static and dynamic characteristics, a clinched joining followed by a tensile-shear test was numerically simulated using the finite element analysis. The design parameters were also evaluated for the geometry of the tapered hole by the Taguchi method in order to improve and compare the lateral joining strength of the clinched joint. The influence of the neck thickness and the undercut were evaluated and the contribution of each design parameter was determined. Then, actual experiments for the joining and tensile-shear test were conducted to verify the results of the numerical simulations. In conclusion, the appropriate combination of the design parameters can improve the joining strength and the cross-sections of the tapered-hole clinched joint formed in the actual experiments were in good agreement with the results of the numerical simulations.