• Journal of Power System Engineering
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• v.21 no.4
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• pp.94-99
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• 2017

Single walled carbon nanotubes were mixed with various metal powders by mechanical ball milling and sintered by spark plasma sintering processes. Two compositional (0.1 and 1 vol%) of the single walled carbon nanotubes were dispersed onto the pure aluminum, 5052 aluminum alloy, pure titanium, Ti6Al4Vanadium alloy, pure copper, and stainless steel 316L. Each composite powders were spark plasma sintered at $600^{\circ}C$ and well synthesized regardless of the matrices. Vickers hardness of the composite materials was measured and they exhibited higher values regardless of the carbon nanotubes composition than those of the pure materials. Moreover, single walled carbon nanotubes reinforced copper matrix composites showed highest enhancement between the other metal matrices system. We believe that low energy mechanical ball milling and spark plasma sintering processes are useful tool for fabricating of the carbon nanotubes-reinforced various metal matrices composite materials. The single walled carbon nanotubes-reinforced various metal matrices composite materials could be used as an engineering parts in many kind of industrial fields such as aviation, transportation and electro technologies etc. However, detail strengthening mechanism should be carefully investigated.

• Journal of Welding and Joining
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• v.7 no.1
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• pp.28-35
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• 1989

The fatigue crack growth behavior in GTA butt welded joints of Al-Alloy 5052-H38 was examined using Single Edge Notched(SEN) specimens. It is well known that welding residual stress has marked influence on fatigue crack growth rate in welded structure. In the general area of fatigue crack growth in the presence of residual stress, it is noted that the correction of stress intensity factor (K) to account for residual stress is important for the determination of both stress intensity factor range(.DELTA.K) and stress ratio(R) during a loading cycle. The crack growth rate(da/dN) in welded joints were correlated with the effective stress intensity factor range(.DELTA.Keff) which was estimated by superposition of the respective stress intensity factors for the residual stress field and for the applied stress. However, redistribution of residual stress occurs during crack growth and its effect is not negligible. In this study, fatigue crack growth characteristics of the welded joints were examined by using superposition of redistributed residual stress and discussed in comparison with the results of the initial welding residual stress superposition.

• International Journal of Aerospace System Engineering
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• v.1 no.1
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• pp.16-20
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• 2014

Recently, various kinds of study on light weight structure are performing in the world. The Al honeycomb sandwich structural type adopt for improvement of lightness and structural stability to major part structure of aircraft or spacecraft. Adhesion badness properties of adhesive and adhesion properties of fillet mainly studied about al honeycomb structure. But study for adhesive properties of sandwich construction with surface treatment of Aluminum alloy barely performed. In this study, adhesive film was used between Al and honeycomb core of honeycomb panel[1]. The study for adhesive properties of sandwich construction with surface treatment of AA 5052 skin was performed.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.73-79
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• 2003

Fatigue test is conducted to see the effect of pre-indentation on the fatigue crack retardation of Al5052-H18 plate. Metallographic observation is introduced to deduce the relationship between fatigue crack retardation and fracture appearance with indentation. The grain size of the specimen becomes smaller with the increase of indentation force and the plastic zone is formed with the decrease of grain size. The fatigue striations are appeared densely as the Indentation force becomes higher. Metallographic observation and fatigue test results show that the indentation force has the limited value in improving fatigue crack retardation. Important point to retard the fatigue crack growth is that the crack growth path should pass through the indented area.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.33-41
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• 2000

Fiber reinforced metal laminates(FRMLs) were new type of hybrid materials. FRMLs consist of high strength metals(Al 5052-H34) and laminated fiber with structural adhesive bond. The effect of resin mixture ratios on the fatigue crack propagation behavior and mechanical properties of aramid fiber reinforced aluminum composites was investigated. The epoxy, diglycidylether of bisphenol A(DGEBA), was cured with methylene dianiline(MDA) with or without an accelerator(K-54). Eight kinds of resin mixture ratio were used for the experiment ; five kinds of FRMLs(1)(mixture of epoxy and curing agent) and three kinds of FRMLs(2)mixture of epoxy, curing agent and accelerator). The characteristic of fatigue crack propagation behavior and mechanical properties FRMLs(2) shows more effecting than that of FRMLs(1).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.3
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• pp.50-57
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• 1996

This study was performed the blankholding force and Vee-ring effects on blanking characteristics, such as maximum blanking force, burnish, dish-shape, hardness. etc. in fine-blanking die by the experimental method. Two types of aluminum (Al.1050-O, Al, 5052-H) Such as annealed and unannealed materials were used for the experiment. In order to get a hydrostatic pressure effect, the clearance was set to 0.5% of the thickness of strip, and the counter punch and stripper plate with Vee-ring was set-up. While this experiment was carry8ing out, the average blanking velocity was constant (37.5mm/sec). As a result of this study, we got a good surface roughness and a dimensions, the good squareness and the reduction of dish-shape could be obtained, and also the additional results obtained were such that the hardness of shear plane was increased and the maximum blanking force was reduce in the condition of Vee-ring height of 1.0~1.5mm, and blankholding force of 1200kg.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.800-803
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• 2002

This investigation describes and analyses the experimental results proper to the penetration of Al5052-H34 alloy plates of thickness 6, 12 and 16mm(T/D＝1, 2, 3) by 5.56mm ball projectiles over the velocity range 350-750㎧. All the high velocity impact tests were carried out at normal impact angle, i.e. zero obliquity. The experimental results presented the variation of depth of penetration, bulge height and diameter, plugged length and diameter with the velocity fur tests on each plate of a given thickness in order to determine the deformation shapes of 5.56mm ball projectiles and targets. Also the protection ballistic limit($V_50$) tests were conducted.

• Transactions of Materials Processing
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• v.19 no.4
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• pp.217-223
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• 2010

The objective of this study is to propose the FE model for mechanical clinched joint using cohesive zone model to analyze its failure behavior under impact loading. Cohesive zone model (CZM) is two-parameter failure criteria approach, which could describe the failure behavior of joint using critical stress and fracture toughness. In this study, the relationship between failure behavior of mechanical clinched joint and fracture parameters is investigated by FE analysis with CZM. Using this relationship, the critical stress and fracture toughness for tensile and shear mode are determined by H-type tensile test and lap shear test, which were made of 5052 aluminum alloy. The fracture parameters were applied to the tophat impact test to evaluate the crashworthiness. Compared penetration depth and energy absorption at the point where 50% of total displacement in result of FE analysis and experiment test for impact test, those has shown similar crashworthiness.

• Journal of the Korean institute of surface engineering
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• v.54 no.1
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• pp.30-36
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• 2021

In this study, double-layered anodizing films were formed on Al 5052 and Al 6061 alloys consecutively first in sulfuric acid and then in oxalic acid, and hardness, withstand voltage, surface roughness and acid resistance of the anodizing films were compared with single-layered anodizing films in sulfuric acid and oxalic acid electrolytes. Hardness of the double-layered anodizing film decreased with increasing ratio of inner layer to outer layer for both Al 5052 and Al 6061 alloys, suggesting that outer anodizing film formed in sulfuric acid electrolyte is damaged during the second anodizing in oxalic acid electrolyte. Withstand voltage of the double-layered anodizing films increased with increasing the thickness ratio of inner layer to outer layer. Surface roughness of the double-layered anodizing films were comparable with that of single-layered anodizing film formed in sulfuric acid but higher than that of single layer anodizing film formed in oxalic acid electrolyte. In acid resistance test, all of the double-layered and single-layered anodizing films showed good acid resistance more than 3 h without any visible gas evolution, which is attributable to sealing of pores. Based on the experimental results obtained in this work, it is possible to design a double-layered anodizing film with cost-effectiveness and improved physical and electrical properties by combining two consecutive anodizing processes of sulfuric acid anodizing and oxalic acid anodizing methods.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.1-7
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• 2015

Self-piercing riveting (SPR) process is gaining popularity due to its many advantages. The SPR does not require a pre-drilled hole and has capability to join a wide range of similar or dissimilar materials and combinations of materials. This study investigated the fatigue strength of self-piercing rivet joint with aluminum alloy (Al-5052) and steel (SPCC) sheets. Static and fatigue tests on tensile-shear specimens were conducted. From the static strength aspect, the optimal punching force for the specimen with upper SPCC (U.S) sheet and lower aluminum alloy(L.A) sheets was 34 kN. During static test the specimens fractured in pull-out fracture mode due to influence of plastic deformation of joining area. There was a relationship between applied load amplitude $P_{amp}$ and number of cycles N ; $P_{amp}=19588N_f^{-0.211}$ and $P_{amp}=4885N_f^{-0.083}$ for U.S-L.A and U.A-L.S specimens, respectively. U.A-L.S fatigue specimens failed due to fretting crack initiation around the rivet neck between upper and lower sheets.