• Journal of Welding and Joining
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• v.3 no.2
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• pp.42-51
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• 1985

The dynamic fracture toughness, fracture characteristics, impact tension and tensile properties of Al-Mg-Si T5 alloy and Al-Zn-Mg T6 alloy respectively welded with filler metal of Alcan 4043 were investigated. The dynamic fracture toughness values were obtained rapidly and simply for the specimen of small size by using instrumented Chirpy impact testing machine. the testing temperatures of the specimen were a range of room temperature and-196.deg. C. The results obtained in this experiment are summarized as follows. With decreasing the testing temperatures, dynamic tensile stress and fracture load were increased, on the other hand the deflection and impact value showed decreasing tendency in order of base metal>HAZ>weld. Changes of total absorbed energy were more influenced by the crack propagation energy than the crack initiation energy. At the low temperatures, the unstable rapid fracture representing the crack propagation appeared for the specimens of Charpy press side notched in Al-Zn-Mg alloy, but it was difficult to obtain the unstable rapid fracture in Al-Mg-Si alloy. Because of the development of plastic zone at the notch root, it was difficult to obtain thevalid $K_{1d}$ value in Al-Mg-Si alloy. Therefore the fatigue cracked specimens were effective in both Al-Mg-Si and Al-Zn-Mg alloys. With decreasing the impact testing temperatures, specimens underwent a transition from dimple-type transgranular fracture to lamella surface-type intergranular fracture because of the precipitate at the grain boundaries, impurities and crystal structure of the precipitates.s.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.1
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• pp.9-16
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• 2011

Primary water stress corrosion cracking (PWSCC) has been found in the weld region of the nuclear power plant. Welding can produce tensile residual stress. Tensile residual stress contributes to the initiation and growth of PWSCC. It is important to estimate weld residual stress accurately to predict or prevent the initiation and growth of PWSCC. This paper shows the results of finite element analysis and measurement experiment for weld residual stress. For the study, four kinds of specimen were fabricated with the materials used in the nuclear power plant. Residual stresses were measured by four kinds of methods of hole drilling, x-ray diffraction, instrumented indentation and sectioning. Through the study, numerical analysis and measurement results were compared and the characteristics of each measurement technique were observed.

• Journal of the Korean Society of Clothing and Textiles
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• v.9 no.1
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• pp.47-55
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• 1985

To determine the change of the mechanical properties of the wool/polyester blend fabrics in proportion to blend ratio, 10 mechanical properties were measured on 6 blend fabrics by KES-F system. Blend ratio on the 6 blend fabrics was increased by $20\%$, and the structure of the fabric were plain, 2/2 twill, respectively. And wearing performances in propoetion to blend ratio on the 6 blend fabrics were investigated. In this experiment. the following conclusions were obtained with the increase of blend ratio of polyester. 1) The values of WT, RT in tensile properties. tensile energy and elongation, and RC in compressional properties were decreased. 2) The values of B, 2HB in bending properties, 2HG. 2HG 5 in shearing properties were increased. 3) Putting on clothes, wearing performance was bad because crumbling of shape and wrinkle were easily made an appearance. Particularly it was remarkably bad as blend ratio of polyester was expressed $60\%$.

• Textile Coloration and Finishing
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• v.18 no.6 s.91
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• pp.37-42
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• 2006

Researches to preserve and restore the remaining fabrics as costume heritages have been carried out. In this study, in order to artificially restore an excavated silk fabrics, degummed silk fabrics and safflower dyed silk fabrics were prepared for an experiment. These fabrics were photo-degraded by the Xenon arc beam to have various strength retention(100%, 80%, 60%, 40%, 20%). The fine structure and physical properties of Xenon arc treated fabrics were investigated with various techniques such as tensile test, weight loss, wide-angle X-ray diffraction, yellowness, color, SEM etc. Tensile strength and the crystal diffraction intensity of silk fabrics decreased as Xenon arc hem treatment time increased. Weight loss increased slightly. Strength retention was decreased as the Xenon arc beam treatment time goes by. (Yellowness of the undyed silk fabrics and $L^*$ of the dyed silk fabrics increased. Whiteness of the undyed silk fabrics and $b^* of the dyed silk fabrics decreased.) SEM results of the silk fabrics treated Xenon arc beam show that surface was a little damaged.

• Journal of Korea Foundry Society
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• v.13 no.4
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• pp.333-341
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• 1993

The effects of alloying elements on the structure and mechanical properties of compacted/vermicular graphite cast irons containing copper, tin and molubdenum for producing pearlite matrix, and also containing phosphorus and boron for increasing wear resistance, were investigated. The Brinell hardness and ultimate tensile strength of the specimens with the range of compositions, [1.5% Cu-0.05% Sn-(0.2-0.4)% Mo-(0.2-0.6)% P-(0.035-0.070)% B], was found to fall within in the following range, depending on their composition; Brinell hardness of BHN 250-315, ultimate tensile strength of $28.1-40.3kg/mm^2$. It was also found within this experiment that CV graphite cast irons possessing higher amount of phosphide eutectic exhibit better wear resistance, but the wear resistance became deteriorate when the area fraction of phosphide eutectics exceed more than 10%. From these experimental results, it could be concluded that the CV graphite cast iron containing 1.5% Cu, 0.05% Sn, 0.4% Mo, 0.2% P and 0.035% B showed good mechanical and wear resistance properties.

• Journal of Power System Engineering
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• v.18 no.2
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• pp.50-56
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• 2014

Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, for the friction welding with tube-to-tube shape, the feasibility of industry application was determined using analyzing mechanical properties of weld and optimized welding variables was suggested. In order to accomplish this object, rotating speed, friction heating pressure, and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. Weld characteristic was investigated in terms of weld shape and metal loss, and 7mm of metal loss was regarded as the optimal metal loss. By tensile test, tensile strength and yielding strength was measured and fracture was occurred at base metal. In order to optimize the welding condition, fitness function was defined with respect to metal loss and yielding strength and the fitness values for each welding condition could be calculated in experimental range. Consequently, we set the optimal welding condition as the point which had maximum value of fitness function. As the result of this paper the optimal welding variables could be suggested as rotating speed was 1300 rpm, friction heating pressure was 15 MPa, and friction heating time was 10 sec.

• The Journal of Korean Academy of Prosthodontics
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• v.19 no.1
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• pp.61-73
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• 1981

The effects of the opaque porcelain firing temperature, the bonding agent and the degassing prior to the opaque firing On the bond strength were investigated by means of the tensile shear stIe$. The diffusional behaviours at the interface of the porcelain and the alloy, and .the microstructures of the ceramic and metal composite were studied for understanding the bonding mechanism. The results obtained in this experiment were summarizd as follow; 1. With no application of bonding agent, the tensile shear strength of the specimen firing at $1840^{\circ}F$ was higher than that of the specimen firing at $1760^{\circ}F$. 2. The highest bond strength was obtained by application of bonding agent without degassing prior to the opaque firing. 3. Application of bonding agent after the degassing showed the lowest bond strength. 4. The greater number of pores were observed at the firing temperature of $1840^{\circ}F$ than that of $1760^{\circ}F$ in the porcelain and the interface respectively.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.146-154
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• 2010

In this study the experimental results of fatigue specimen for the Strand Stay Cable Assembly of Extadosed bridges is investigated. The fatigue test and tensile experiment is conducted to 6 kinds of specimens. Test specimen OVM250-31 Strand Cable System manufactured by china OVM B-Machinery Co., Ltd, and OVM250-42 Parallel Strand Stay Cable Assembly manufactured by china OVM B-Machinery Co., Ltd, are passed for fatigue test and rupture tensile test. But Test specimen OVM250-42 Parallel Strand Stay Cable Assembly manufactured by korean A-Machinery Co., Ltd, is not passed for fatigue test conducted according to the "Recommendation for Stay Cable Design. The test result are compared to the fatigue criteria of PHI 2001 for cyclic load, and it is concluded that the current korean design code will be needed for representing the fatigue load in Hot Dip Galvanized Strand Stay Cable. It is verified that the new korean specification and quality criteria of Strand Stay Cable and exact experimental applied process will be needed.

• Steel and Composite Structures
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• v.20 no.3
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• pp.487-500
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• 2016

In order to investigate the flexural bearing capacity of panel zone of diaphragm-through joint between concrete filled square steel tubular column and steel beam, four specimens were tested under static tension loads to study the mechanical properties and bearing capacity of diaphragm-through joints with a failure mode of panel zone. Finite element models of these specimens were developed to simulate the test and compare the predicted failure modes, load-displacement curves and bearing capacities with the experimentally observed. It was found that the tensile load from the steel beam flange is mainly shared by the square steel tube and the diaphragm. The diaphragm plastic zone appears along the cross-section lines enclosed by the square steel tube and the influence of steel beam web on the plastic zone of the steel tube is significant and cannot be neglected. Computational models of yield lines on square steel tube and diaphragm are established based on the distribution pattern of the plastic zone, and an analytical method for the evaluation of the bearing capacity of the joint is proposed. The theoretical results and the experimental data are compared and found in good agreement.

• Elastomers and Composites
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• v.30 no.1
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• pp.20-31
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• 1995

The purpose of this study is to investigate the reinforcement of inorganic filler silica, treated by MDI about SBR vulcanizate. The characteristics of vulcanization, physical properties, surface properties and dynamic properties were investigated after mixing those silica with SBR and unmodified silica with SBR. In this experiment only the quantity of silica was variable. In the vulcanization characteristics tested by rheometer, S-series showed the fastest scorch $time(t_{10})$ and optimum cure $time(t_{90})$. And in test or tensile characteristics hardness, tensile strength, 100%, 300% modulus and elongation were all appeared in the order of M>S-series. The characteristic bonding of urea between unmodified silica and MDI could be confirmed in IR spectrum. The shapes of silicas treated chemically were observed by SEM. And the dispersion of the filler in the SBR composite was uniform. In the dynamic characteristics by the RDS, the order of elastic modulus G' values was as follows : M>S-series, and also the order of damping values was as follows : M>S-series.