• 한국기계가공학회지
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• 제6권2호
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• pp.17-21
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• 2007

Shearing including punching, blanking, trimming, slitting, etc is one of the most frequently used processes in sheet metal manufacturing. It has been widely used for manufacturing autobody, electronic components, aircraftbody, etc. In this paper, it has been researched by the experiment to examine the effect of burr height corresponding to die clearance, cutting angle, tool sharpness, etc. This paper presents the experimental results with using Al alloy sheet.

• 대한기계학회논문집B
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• 제33권6호
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• pp.411-417
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• 2009

The transient shear stress response of an electrorheological fluid is investigated experimentally. The characteristic time constants of an electrorheological fluid sheared between two concentric cylinders were obtained under various electric field strengths and shear rates. Also, two experimental modes are adopted to investigate the effect of the shear flow on the dynamic behavior of the fluid; one is that the electric field is induced before shearing, and the other is the electric field is induced after shearing. From the difference in the response time between two modes, the cluster formation time were obtained. The response times were decreased with the increase of the shear rate, irrelatively of the electric field strength. The cluster formation time were monotonically increased with increase of shear rate, and thereafter, were converged with a certain value.

• 한국기계가공학회지
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• 제21권8호
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• pp.87-92
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• 2022

The Al3003 aluminum plate was cut by grinding, milling, sawing, and shearing, and the hard-anodizing surface of the material was investigated. Large burrs were formed during grinding and milling. The brittle anodized film split and migrated along the deformed aluminum surface. During shearing, the hard-anodized film on the blade entry surface cracks and slides along the deforming aluminum. The cutting heat increased the ductility of the aluminum and further promoted burr formation. The oil-based coolant suppressed burrs and prevented chips from sticking to the endmill. It is better to avoid the high cutting speed and slow material feed rate conditions, which increase the cutting temperature and burr in the band saw.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1999년도 가을 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.385-390
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• 1999

• 대한약학회:학술대회논문집
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• 대한약학회 2000년도 NEW STRATEGY FOR DRUG DEVELOPMENT IN POST-GENOMIC ERA(대한약학회)
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• pp.277.3-278
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• 2000

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2939-2948
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• 2020

This paper presents an analytic solution procedure of the rotationally restrained hinged-hinged beam subjected to transverse motions at supports based on EBT (Euler-Bernoulli beam theory). The EBT solutions are compared with the solutions based on TBT (Timoshenko beam theory) for a wide range of the rotational restraint parameter (kL/EI) of slender beams whose slenderness ratio is greater than 100. The comparison shows the followings. The internal loads such as bending moment and shearing force of an extremely thin beam obtained by EBT show a good agreement with those obtained by TBT. But the discrepancy between two solutions of internal loads tends to increase as the slenderness ratio decreases. A careful examination shows that the discrepancy of the internal loads originates from their dynamic components whereas their static components show a little difference between EBT and TBT. This result suggests that TBT should be employed even for slender beams to consider the rotational effect and the shear deformation effect on dynamic components of the internal loads. The influence of the parameter on boundary conditions is examined by manipulating the spring stiffness from zero to a sufficiently large value.

• Geomechanics and Engineering
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• 제30권3호
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• pp.219-231
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• 2022

Geotechnical materials such as silt, fine sand, or coarse granular soils may be unstable under undrained shearing or during rainfall infiltration starting an unsaturated state. Some researches are available describing the instability of coarse granular soils in drained or undrained conditions. However, there is a need to investigate the instability mechanism of unsaturated silty soil considering the effect of degree of compaction and net confining stress under partially and fully drained conditions. The specimens in the current study are compacted at 65%, 75%, & 85% degree of compaction, confined at pressures of 60, 80 & 120 kPa, and tested in partially and fully drained conditions. The tests have been performed in two steps. In Step-I, the specimens were sheared in constant water content conditions (a type of partially drained test) to the maximum shear stress. In Step-II, shearing was carried in constant suction conditions (a type of fully undrained test) by keeping shear stress constant. At the start of Step-II, PWP was increased in steps to decrease matric suction (which was then kept constant) and start water infiltration. The test results showed that soil instability is affected much by variation in the degree of compaction and confining stresses. It is also observed that loose and medium dense soils are vulnerable to pre-failure instability i.e., instability occurs before reaching the failure state, whereas, instability in dense soils instigates together with the failure i.e., failure line (FL) and instability line (IL) are found to be unique.

• Corrosion Science and Technology
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• 제23권3호
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• pp.215-220
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• 2024

Recently, the demand for Zn-Ni electrogalvanized steel sheets for home appliances and automobiles is increasing. Products should have a thick plating (30 to 40 g/m²) on both side with a thin thickness (≤ 0.8 mm) and the highest surface quality. By a high current density operation, current is concentrated in the edge part of the steel sheet, resulting in large surface dent defects due to dendritic plating. This can lead to a low productivity due to low line speed operation. To solve this problem, this study aimed to identify factors influencing dendritic plating. A cylindrical electroplating device was manufactured. Effects of cut edge shape and thickness of steel plate, current density, temperature, flow rate, electrolyte concentration, and pH on dendrite generation of Zn-Ni electroplating were examined. To investigate effect of edge shape of the steel sheet, the steel sheet was manufactured using three processing methods: shearing, polishing after shearing, and laser. Relative effects thickness and cut edge processing methods of the steel plate, current density, temperature, flow rate, electrolyte concentration, and pH of plating solution on dendrite plating were investigated. To prevent dendrite plating, an edge mask was manufactured and its application effect was investigated.

• Design & Manufacturing
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• 제18권2호
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• pp.23-28
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• 2024

The automobile industry is a wide range of related industries, including parts manufacturing and vehicle assembly, press processing is an essential element in making automobiles. Press processing is a processing method for metal sheets that has relatively high dimensional and shape precision and is suitable for mass production. It refers to processing by attaching a special tool, a mold, to a press machine. Recently, the automobile industry is attempting to reduce the weight of automobiles in order to reduce carbon emissions due to global warming, and the use of high-strength steel sheets, which are lighter than general structural steel sheets, is a natural trend. Shear processing is required to use high-strength steel, and the shape of the shear surface created by shear processing has a significant impact on the quality of the automobile. Therefore, various methods are being attempted to improve the share surface during shear processing. Among them, shaving processing is a method of shearing the primary shearing area again, and it is difficult to obtain an accurate answer because complex deformation occurs in the microscopic shear area. Therefore, in this study, the effect of machining allowance on shaving processing was analyzed using the finite element method using high-strength steel plate (SPFH590), and the differences were compared and examined through actual experiments under the same conditions.

• 한국지반공학회지:지반
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• 제12권3호
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• pp.49-62
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• 1996

인발시험은 보강토 구조물의 설계에 있어 보강재와 흙사이의 강도 정수를 결정하는데 사용된다. 그러나 이 시험의 해석시 보강재를 따라 발생하는 전단강도가 일정한 것으로 가정하는데 이는 인발시험중 흙과 보강재 사이의 점진성 전단으로 인해 흙과 보강재의 전단-변위 관계 계산시 오류가 발생하게 된다. 구과 보강재 사이의 shear stiffness계산시 점진성전단의 영향을 평가하기 위하여 유한요소법으로 인발시헙을 해석하였다. 흙과 보강재는 선형과 비선형거동으로 채석하였고 shear stiffnss는 일반적인 방법으로 계산하였는데 수정된 shear stiffness와는 많은 차이가 있었으며 그 차이로 인해 유한요소해석의 결과가 달라지게 된다. 본 논문에서는 유한요소해석결과와 시험치를 비교 분석하였으며 개선된 인발시험 해극방법에 대하여 논하였다.