Wyniki wyszukiwania - BazTech

1

Effect of Trace Elements (Co, Cr) on the Microstructure and Physical Properties of Al-Si-Cu-Mg-Fe Extruded Alloy

Ahn S. S., Sharief P., Lee C. H., Son H. T., Kim Y. H., Kim Y. C., Hong S., Hong S. J.

Archives of Metallurgy and Materials

|

2019

|

Vol. 64, iss. 3

857--862

EN

Trace elements Co, Cr were added to investigate their influence on the microstructure and physical properties of Al-Si extruded alloy. The Co, Cr elements were randomly distributed in the matrix, forms intermetallic phase and their existence wereconfirmed by XRD, EDS and SEM analysis. With addition of trace elements, the microstructure was modified, Si particle size was reduced and the growth rate of β-(Al5 FeSi) phase limited. Compared to parent alloy, hardness and tensile strength were enhanced while the linear coefficient of thermal expansion (CTE) was significantly reduced by 42.4% and 16.05% with Co and Cr addition respectively. It is considered that the low CTE occurs with addition of Co was due to the formation of intermetallic compound having low coefficient of thermal expansion. The results suggested that Co acts as an effective element in improving the mechanical properties of Al-Si alloy.

2

A Study on Changes in Thickness of STS304 Material in the Progressive Drawing Process

Lee C. K., Kim Y. C.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 2B

1319--1323

EN

In the drawing process, the roundness of corners in the punch and the die are very important factors in determining the thicknesses of the product. The results clearly revealed that the thickness of a flange was increased and the thickness of body parts reduced when the roundness of the die entrance was small. The material thickness of the top part was decreased when the corner roundness of the punch was large. The smooth inflow of materials was found to have a significant effect on the thickness during the post-process. The compressive strength of STS 304 material exhibited a higher value compared with other processing methods. Moreover, we clearly observed the corner roundness of the punch and the die to be a very important factor for STS 304 materials.

3

Experimental Study On Fracture Property Of Tapered Double Cantilever Beam Specimen With Aluminum Foam

Kim Y. C., Kim S. S., Cho J. U.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1459--1462

EN

It is indispensable to evaluate fracture energy as the bonding strength of adhesive at composite material with aluminum foam. This specimen is designed with tapered double cantilever beam by British standards (BS 7991 and ISO 11343). 4 kinds of specimens due to m values of 2, 2.5, 3 and 3.5 are manufactured and compared each other with the experimental results. Adhesive fracture energy is calculated from the formulae of British standards. The value of m is the gradient which is denoted as the length and the height of specimen. As m becomes greater at static experimental result, the maximum load becomes higher and the displacement becomes lower. And the critical fracture energy becomes higher. As m becomes less at fatigue experimental result, the displacement becomes higher and the critical fracture energy becomes higher. Fracture behavior of adhesive can be analyzed by this study and these experimental results can be applied into real field effectively. The stability on TDCB structure bonded with aluminum foam composite can be predicted by use of this experimental result. Adhesive fracture energy is calculated from the formulae of British standards. Based on correlations obtained in this study, the fracture behavior of bonded material would possibly be analyzed and aluminum foam material bonded with adhesive would be applied to a composite structure in various fields, thereby analyzing the mechanical and fracture characteristic of the material.

4

Experimental Study On Fracture Property Of Double Cantilever Beam Specimen With Aluminum Foam

Kim Y. C., Choi H. K., Cho J. U.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1151--1154

EN

This study aims to investigate double cantilever beam specimen with aluminum foam bonded by spray adhesive to investigate the fracture strength of the adhesive joint experimentally. The fracture energy at opening mode is calculated by the formulae of British Engineering Standard (BS 7991) and International Standard (ISO 11343). For the static experiment, four types of specimens with the heights (h) of 25 mm, 30 mm, 35 mm and 40 mm are manufactured and the experimental results are compared with each other. As the height becomes greater, the fracture energy becomes higher. After the length of crack reaches 150 mm, the fracture energy of the specimen (h=35 mm) is greater than that of the specimen (h=40 mm). Fatigue test is also performed with DCB test specimen. As the height decreases, the fracture energy becomes higher. By the result obtained from this study, aluminum foam with adhesive joint can be applied to actual composite structure and its fracture property can possibly be anticipated.

5

An Analysis Of Stress Intensity Factor Due To Normal Stress For A Cracked Plate Reinforced With A Sheet By Seam Welding

Kim O.-H., Kim Y. C.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1441--1444

EN

It is essential in damage tolerance design to determine the stress intensity factor theoretically. The stress intensity factor for a cracked plate that is reinforced with a sheet by seam welding is determined theoretically and plotted as function of the seam welding location and stiffness ratio. The singular integral equation is derived based on the compatibility condition between the cracked plate and the reinforcement plate, and it is solved by means of Erdogan and Gupta‘s method. The theory is verified by comparing the results of the present analysis with those of a numerical analysis. The results from the present analysis show that the reinforcement effect improves as the welding line is situated closer to the crack and as the stiffness ratio of the cracked plate and the reinforcement plate increases.

6

A Study Of The Die Roll Height Of SHP-1 And SCP-1 Materials In The Fine Blanking Process

Lee C. K., Kim Y. C.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1397--1402

EN

The height of the die roll, the distance of the V-ring, and the shear rate were varied with the aim of investigating the effects of the applied changes on the fine blanking line in a cold-rolled and a pickled steel sheet, referred to as SCP-1 and SHP-1, respectively. Both materials consisted primarily of a ferrite phase with small amounts of impurities including F, Mn, and Cr. The distance was found to be a very important factor in controlling the shear of the V-ring in the fine blanking process. When the position of the V-ring was set at distances of 1.5 mm and 2 mm, the die roll height increased with increasing shear speeds from 6.4 m/min to 10 and 16 m/min. Analysis of the influence of the shear rate revealed that low rates resulted in the lowest die roll heights since the flow of material was effectively inhibited.

7

Optimized pattern design of light-guide plate (LGP)

Kim Y. C., Oh T. S., Lee Y. M.

Optica Applicata

|

2011

|

Vol. 41, nr 4

863--872

EN

We have investigated the light intensity distributions of a 7-inch LGP to increase output illuminance uniformity by reducing the bright and dark areas caused by a plurality of LED. We analyzed the effects of the LED–LED gap and LED–LGP space to the light intensity distribution in the LGP inside. We have found that the density function of LGP pattern has a simple exponential terms. We analyzed the output light intensity of the LGP through the comparison of the simulation results between adopting the hemisphere pattern density function and adopting the equidistance pattern density function. And also, to reduce the bright spot and dark areas, we have introduced a convex elliptical LED reflector. As a result, the output illuminance uniformity was improved effectively by the adoption of the pattern density function and the new LED reflector.