• 한국정밀공학회지
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• 제28권11호
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• pp.1272-1278
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• 2011

Mechanisms of the robot system should be developed according to the task. In this study, we propose improving adaptability of the robot mechanism with the modularized joint mechanism. Adaptability is the measure of the system ability to cope with change or uncertainty. Modular type joint has been widely used in development of various robots including reconfigurable robots. To build robotic systems more flexibly and quickly with low costs of manufacturing and maintenance, we have designed a modular type joint with one degree of freedom for general purpose. This module is designed to be compact, light-weight and self-controlled. In this design, we consider the kinematics and dynamics properties of the modular type joint.

• 대한기계학회논문집
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• 제18권6호
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• pp.1412-1420
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• 1994

The adhesively bonded tubular double lap joint has better torque transmission capability and reliability in bonding operation than the single lap joint. In this paper, an analytic solution for the torque transmission capabilities and stress distributions of the adhesively bonded tubular double lap joint was derived assuming the linear properties of the adhesive and adherends. From the calculation, it was found that the torque transmission capabilities of the double lap joint was more than 40% larger compared to that of the single lap joint.

• 대한기계학회논문집A
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• 제27권10호
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• pp.1636-1643
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• 2003

In this study, bolted joint made of Glass-Mat Reinforced Thermoplastics (GMT) specimen was under tensile loading to investigate the relation between joint strength and glass-fiber weight fraction of the flat plate specimen. The effect of molding conditions such as the initial size of a GMT charge and molding temperatures was investigated under plane strain condition. In consideration of the specimen geometry, minimum end distance and width of the specimen to induce the bearing fracture mode of the bolted joint were determined. And finally, the effect of the outer diameter of washer and clamping pressure on joint strength was also investigated. Since joint strength is dependent on the local glass-fiber weight fraction, experimentally measured strength was modified, considering its irregular values of the specimen molded under various processing conditions in order to obtain a reasonable correlation between the two.

• 대한기계학회논문집A
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• 제22권4호
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• pp.905-915
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• 1998

Static tensile tests using adhesive-bonded single-lap joints of aluminum alloy were conducted to investigate the effect of geometric factor, overlap length, adherend thickness, adhesive thickness and material composition of adherend/adhesive on the strength of adhesive joint. The average applied shear stress at joint fracture decreased with increasing lap length. However increasing the adherend thickness resulted in a higher joint strength. Higher yield strength of adherend and lower elastic modulus of adhesive is advantageous to the adhesive joint. Newly proposed modified joint factor could be well evaluated the influence of lap length, adherend thickness and adhesive thickness on the bond strength for adhesive joints.

• Structural Engineering and Mechanics
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• 제13권1호
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• pp.1-16
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• 2002

This paper presents the findings of an investigation carried out to determine the most appropriate connections, in terms of rotational stiffness, to use for the optimum design of cold-formed Zed section sleeve joint purlin system. Experiments and parametric studies were conducted to investigate the effects of geometric variables on the behavior of the sleeve-purlin and cleat-purlin connections of the sleeve joint purlin system. The variables considered were purlin size and thickness, sleeve size, thickness, length and bolt position. The test results were used to verify the empirical expressions, developed herein, employed to determine the rotational stiffness of connections. With the predicted connection stiffness, the most suitable sleeve-purlin and cleat-purlin connections can be selected so as to produce an optimum condition for the sleeve joint purlin system.

• Composites Research
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• 제31권4호
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• pp.151-155
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• 2018

기계적 조인트와 접착 조인트는 구조물의 일반적인 접합 방법이다. 접착 조인트는 기계적 체결법에 비해 넓은 면적에 하중이 분포되고 우수한 피로 특성을 가진다. 이러한 특성에도 불구하고, 접착 조인트는 환경조건이나 작업자의 숙련도에 대한 접착 건전성이 크게 달라진다. 따라서 접착 조인트의 건전성을 평가 할 수 있는 기술이 필요하다. CNT를 접착제에 분산시켜 접착조인트의 전기적 특성을 측정하는 전기저항법은 결함을 검출하는 매우 유망한 기술이다. 본 논문에서는 초음파 분쇄기와 3-roll-mill을 이용하여 접착제에 CNT를 균일하게 분산시켰으며, 알루미늄-알루미늄 단일 접착 조인트를 제작하여 탄소나노튜브(CNT) 함량에 따른 정적 강도의 변화를 평가하고, 전기저항법을 이용하여 결함탐지능을 평가하였다.

• 대한기계학회논문집A
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• 제36권12호
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• pp.1591-1597
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• 2012

복합재료 접합부의 접착강도에 대한 접착면 성질의 영향을 알아 보기 위해 불포화폴리에스테르, 우븐과 매트 유리섬유를 사용하여 복합재료 접합시편들을 제작하였다. 접착제, 복합재료 접착물, 말단접합과 이차접합 시편들의 기계적 성질을 실험에 의해 구하고 실험결과를 접합이론에 적용하였다. 6 개의 접합부들에서 발생하는 최대 및 평균 전단 응력은 최대 인장력과 접합 시편의 기하학적 변수들로부터 계산되었다. 실험 결과 접합면을 연마한 후 아세톤으로 처리한 경우가 말단접합의 3 가지 형태 중 가장 큰 강도를 가지고 있음이 관찰되었다. 마찬가지로 매트-매트와 매트-우븐 접합이 거의 같은 값으로 이차 접합의 3 가지 형태 중 가장 큰 강도를 가지고 있었다. 반대로 아무 처리도 하지 않은 접합시편과 우븐-우븐 접합시편은 매우 낮은 강도를 가졌다. 각각의 경우 파손은 접합부 양끝에서 심하게 발생하였고 접합부 가운데로 이동하였다.

• 한국운동역학회지
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• 제15권1호
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• pp.19-28
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• 2005

The purpose of this study was to improve the ankle joint to mechanical energy in Crouching start according to the backward block inclined angle(F, F(+1), F(+2)) increase. For purpose of this study the ankle joint was considered as a single hinge joint rotation about a transverse axis. A two-dimensional(sagittal plane) analysis was performed on data collected from 3 spriters(university student). During Crouching start, the ankle joint moment showed a similar patterns according to the backward block inclined angle increase. The peak values of ankle joint moment was plantar flexion approximately 80% throughout the contact phase for Crouching start. The absorbed and generated energy represented different values from the backward block inclined angle increase at ankle joint. On the backward block inclined angle F, subject A($55^{\circ}$) and C($50^{\circ}$) Produced energy generation more than other block inclined angles. On the backward block inclined angle F(+2), subject B($50^{\circ}$) showed largest energy generation.

• 열처리공학회지
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• 제17권4호
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• pp.230-235
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• 2004

Present work was carried out to investigate the influence of welded conditions, such as welding current, diameter of welding wire on the microstructural change and mechanical properties of TIG welded joint in AZ31B Mg alloy. It was found that good and sound welded joint was achieved in all welding conditions. The grain size decreased with increasing welding current and decreasing diameter of welding wire. Also, the second phases were homogeneously distributed in the grain and grain boundary as decreasing welding current and diameter of welding wire. The ${\beta}$ discontinuos precipitates were observed in the welded joint, but this microstructure has not been reported by previous researchs in AZ31B Mg alloy. The hardness value is affected by the existence state of the second phase and the hardness of the welded joint region is lower than the other regions in welded AZ31B Mg alloy. The strength of the welded joint region was influenced by the grain size and has more than 90%, compared to that of ASTM standard specification.

• Advances in nano research
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• 제14권2호
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• pp.117-126
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• 2023

This experimental study investigated friction stir welding (FSW) of the acrylonitrile-butadiene-styrene (ABS) T-joint in the presence of various nano-silica levels. This study aim to handle the drawbacks of the friction stir welding (FSW) of an ABS T-joint with various quantity of nanoparticles and assess the performance of nanoparticles in the welded joint. Moreover, the relationship between the nanoparticle quantity and FSW was analyzed using response surface methodology (RSM) Box-Behnken design. The input parameters were the tool rotation speed (400, 600, 800 rpm), the transverse speed (20, 30, 40 mm/min), and the nano-silica level (0.8, 1.6, 2.4 g). The tensile strength of the prepared specimens was determined by the universal testing machine. Silica nanoparticles were used to improve the mechanical properties (the tensile strength) of ABS and investigate the effect of various FSW parameters on the ABS T-joint. The results of Box-Behnken RSM revealed that sound joints with desired characteristics and efficiency are fabricated at tool rotation speed 755 rpm, transverse speed 20 mm/min, and nano-silica level 2.4 g. The scanning electron microscope (SEM) images revealed the crucial role of silica nanoparticles in reinforcing the ABS T-joint. The SEM images also indicated a decrease in the nanoparticle size by the tool rotation, leading to the filling and improvement of seams formed during FSW of the ABS T-joint.