• Journal of KSNVE
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• v.6 no.3
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• pp.305-315
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• 1996

Present paper aims at the correlation of modal characteristics of folding fin between test and analysis using an optimization theory. Folding fin is composed of a movable fin, a base fin, and many functional components related to the folding mechanism. Joint parts of folding fin in FEM are initially modeled as rigid elements resulting some difference between test and analysis in modal characteristics. Therefore, some equivalent springs representing joint parts are introduced to improve the FEM model. The springs were set as design variables, while the frequency difference between test and analysis was set as the object function. Bayesian procedure was ujsed for the minimization.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1302-1306
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• 2007

Joints are used extensively in various industries. For instance, structural adhesives are used in place of the traditional mechanical fasteners, such as screws and bolts, because they are much lighter and spread the stresses more uniformly across the joints. For efficient designs of joints, knowledge of static and dynamic characteristics of joints is essential. Most analysis of joints are carried out using analytical equations or finite element method. In this paper, the characteristics of four conditions of lap-joint beam are investigated experimentally. The mode shapes and nodal points of beam show that there are different deformations in each condition. These deformations may cause high stresses and may initiate local cracking and delamination failures.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.334-339
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• 1994

In this work, we propose a planar three degree-of-freedom parallel mechanism as another type of assembly device which utilized joint compliances. These joint compliances can be adjusted either by properly replacing the joint compliances or by actively controlling stiffness at joints, in order to generate the desired operational compliance characteristics at RCC point, The operational compliance matrix for this mechanism is explicitly obtained by symbolic manipulation and its operational compliance characteristics are examined, it is found that the RCC point exists at the center of the workspace when the mechanism maintains symmetric configurations. Compliance characteristic and its sensitivity of this mechanism is analyzed with respect to the magnitude of the diagonal compliance components and two different matrix norms measuring compliance sensitivity. It is expected that the analysis results provide the designer with a helpful information to determine a set of optimal parameters of this RCC mechanism.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.537-547
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• 2000

The tube flange joint often used in the field is a kind of tensional joint method using the high strength bolts. Transferring stress is conducted by high axial pressure between each part of material that is produced by twisting the high strength bolts. And historical characteristics of the flange joint have not been studied sufficiently and it is difficult to say that the design method is established definitely. Therefore new method using ultimate strength is need to be suggested to solve there problems in using flange joint. The purposes in this study are to gain the data base for establishing design method of joint in the form like figure1 and survey whether the joint of tube flange with non-equal diameter can be designed or not in the form like rib or ring.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1082-1090
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• 2008

In this paper, a general solution for the vibrational energy and intensity distribution through a compliant and dissipative joint between plate structures is derived on the basis of energy flow analysis (EFA). The joints are modeled by four sets of springs and dashpots to show their compliancy and dissipation in all four degrees of freedom. First, for the EFA, the power transmission and reflection coefficients for the joint on coupled plate structures connected at arbitrary angles were derived by the wave transmission approach. In numerical applications, EFA is performed using the derived coefficients for coupled plate structures under various joint properties, excitation frequencies, coupling angles, and internal loss factors. Numerical results of the vibrational energy distribution showed that the developed compliant and dissipative joint model successfully predicted the joint characteristics of practical structures vibrating in the medium-to-high frequency ranges. Moreover, the intensity distribution of a compliant and dissipative joint is described.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.723-730
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• 2007

The typical design of automotive driveshafts generally utilizes Constant Velocity(CV) joints as a solution to NVH. CV joints are an integral part of vehicles and significantly affect steering, suspension, and vehicle vibration comfort levels. Thus, CV joints have been favored over universal joints due to the constant velocity torque transfer and plunging capability. Although CV joints are common in vehicle applications, current research works on modeling CV joint friction and assumes constant empirical friction coefficient values. However, such models are long known to be inaccurate, especially under dynamic conditions, which is the case for CV joints. In this paper, an instrumented advanced CV joint friction apparatus was developed to measure the internal friction behavior of CV joints using actual tripod-type joint assemblies. The setup is capable of measuring key performance of friction under different realistic operating conditions of oscillatory speeds, torque and joint installation angles. The apparatus incorporates a custom-installed triaxial force sensor inside of the joint to measure the internal CV joint forces(including friction). Using the designed test setup, the intrinsic interfacial parameters of CV joints were investigated in order to understand their contact and friction mechanisms. The results provide a better understanding of CV joint friction characteristics in developing improved automotive driveshafts.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.53-62
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• 2004

A single layer latticed dome is one of the most efficient structures because of its low specivic gravity. For easily analyzing of a single layer latticed dome, joint system is assumed to be pin or rigid joint. However, its joint uses ball whose system has intermediate properties of pin and rigid joint. Therefore this study has a grasp of bending rigidity, stress and mechanical properties through experimental and analyzing method of the bolt inserted ball joint. To analyze the stress of bolt and sleeve, this study uses through 3D elastic contact and cubic element, and then the ball and the bolt are perfectly connected for easily analyzing Compared experimental results to F.E.M, each specimen has an error of less than 12 percent. In the results of stress distribution through F.E.M, stress occurs from bottom of bolt to top of sleeve, and most of tension appears on the bolt, also compression occurs from upper parts of the bolt to the sleeve. The assumption of bending stiffness in ball joint is well known that bolt resists only tension and upper sleeve resiss compression. The results of experiment and analysis have $7{\sim}56%$ error, assuring that upper part of bolt occurs of partial compression. In the result of modified assumption have $4{\sim}20%$ error.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.45-55
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• 2007

We investigated the biomechanics and characteristics of shoulder rotator muscles for professional woman volleyball players. The purpose of this study was to analyze the isokinetic peak torque and range of motion for shoulder joint rotation. We measured the strength and ROM of the internal rotation(IR) and external rotation(ER) of shoulders joint for nine professional woman Volleyball players and nine University students with Biodex and Simi-motion. 1. We measured peak torques for the shoulder joint rotator at angular velocities of 60/s and 180/s. It was found that the peak torques were significantly different between the two groups and also between the hands used. 2. At angular velocity of 60/s, IR/ER ratio of the shoulder joint was significantly different depending on the groups and the hands in use. There was a significant difference for 'Dominant side' at angular velocity of 180/s, but no significant difference for 'Non-dominant side' and the controls group. 3. Regarding the ROM of rotation of the shoulder joint group, IR was significantly different between the groups and the hands in use. 4. IR/ER ratio of the shoulder joint for Dominant side was quite different between the groups.

• Journal of KSNVE
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• v.9 no.5
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• pp.975-983
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• 1999

This paper describes the dynamic characteristics of the joint structures in case of using the simplified beam model in the F. E. analysis. The modeling errors, when replace the shell with the beam, are investigated through F. E. normal modes analysis. Normal mode analysis were performed to obtain the natural frequencies of the L and T shaped joints with various type of channels. The results were analyzed to access the effects of the models on the accuracy of F.E. analysis by identifying the geometric factors which cause the error. The geometric factors considered are joint angle, channel length, thickness and area ratio of the hollow section to the filled one. The joint stiffness evaluation technique is developed in this study using normal modes analysis with Lumped Mass. With this method, the progressively improved results of F. E. analysis are obtained using the simplified beam model. The static and normal modes analysis are performed with the joint stiffness values obtained by the Kazunori Shimonkakis' virtual stiffness method and the proposed method and these simplified modeling errors are compared.

• Advances in nano research
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• v.14 no.2
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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.