• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.88-95
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• 2011

In this study, the deformation, stress, vibration, fatigue life and the probability of damage are analyzed at the pedal applied by the force of 300N. The maximum stress at the lower of pedal is shown as 20.801MPa. And the maximum displacement is 0.85mm at the maximum response frequency as 3800Hz. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^{5}MPa$ and the amplitude stress of 0 to $10^{5}MPa$, the possibility of maximum damage becomes 0.6%. This stress state can be shown with 5 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively improved with the design of pedal by investigating durability against its damage.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.5-9
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• 2002

This paper presents a method and procedure for stress analysis and sizing in development of structures of a large composite wind turbine blade. Structural requirement of IEC standard was reviewed to set up appropriate analysis method and procedure. Several structural layouts were examined in a viewpoint of a large scale wind turbine blade. For the critical load cases, stress analysis were performed using finite element method. Stacking sequence and thickness of a laminate for each part and location were determined considering stress levels and producibility. Nonlinear geometric analysis was performed to check stability problem due to local buckling of a skin structures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.65-71
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• 2011

This study analyzes about front axle through the analyses of stress, fatigue and vibration. Maximum equivalent stress is shown with the frequency of 60Hz in case of the harmonic vibration analysis applied with force. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-2{\times}10^5MPa$ and the amplitude stress of 0 to $-2{\times}10^5MPa$, the possibility of maximum damage becomes 3%. This stress state can be shown with 6 times more than the damage possibility of 'SAE Bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of front axle by investigating prevention and durability against its damage.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.983-990
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• 2013

Evaluation of the structural analysis for a 70/15 ton${\times}$105 m LLC (Level Luffing Crane) was conducted with an FEM Tool. Due to a discordance of the modeling and element type, the LLC was progressively analyzed after dividing it into the boom, main structure and rocker. All loads such as slewing, traveling and wind load, etc., that are indicated in the reference standards, were inputted as various severe conditions of the LLC. The deformation, equivalent stress(Von Mises stress), buckling characteristics were evaluated for the LLC structures. The stress concentrated areas over the allowable stress were identified, and reinforcement work was performed with a stiffener.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.747-754
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• 2012

A solar power generator is usually installed outdoors and it is exposed to extreme environments such as snow weight and wind loading. The solar tracker structure should be designed to have sufficient stiffness and strength against such loads. In this paper, simulations are performed by varying the parameters such as wind directions, wind speeds and the pose of the solar panel to evaluate the effects of extreme wind on solar tracker. As the effects of wind load, maximum displacement and maximum equivalent stress in the solar tracker are calculated. Finite element stress analysis is carried out by using the pressure distribution that is obtained by prior wind load analysis due to the flow around the solar tracker. The stress analysis of solar tracker to check and/or improve structural robustness provides some useful instructions for structural design or revision of solar tracker.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.504-512
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• 2003

Simulation programs have been developed and used as an attempt to improve the accuracy of Non-Destructive Evaluation(NDE) techniques. The applicability of these programs is very limited, however, because it is difficult to describe the delicacy of the propagation of stress waves. To investigate the applicability of the finite element analysis for stress wave-based NDE techniques numerical simulation for Impact-Echo method and SASW method is performed. The numerical studies are performed to determine the essential parameters such as contact time of impact load, mesh size and time step size. These studies show that the choice of parameter is very important for improving the accuracy and confidence of the numerical procedure and, thereby, the applicability of the numerical analysis for stress wave-based NDE techniques

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.10a
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• pp.59-64
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• 1989

On this condition of steel bridge member having a crack, occasionaly it is improssible to measure of stress history and to extract test specimen. Under this situation, tried to estimate remaining service life from statistical data on traffic and existing results of fatigue test without measuring of stress history and fatigue test. The main results are as following (1) Stress history of simple beam estimated from Montecallo simulation method with probabilistic model of traffic can be use to estimate remaining fatigue life instead of measuring of stress history. (2) In such a case measuring of remaining fatigue life at bridge member haying a crack, influences of RMS model and RMC model on fatigue crack growth rate are not differ without difference of applied stress range. (3) Application of cut off method may be overestimate remaining fatigue life.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.10a
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• pp.29-33
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• 1989

An extended model for the assessment of fatigue reliability of steel structures In the presence of residual stresses Is developed. The model explicitly Includes the uncertainties of the lean stress and residual stress in terms of the zero-mean equivalent stress-range. It Is assumed that the fatigue life of welded Joints follows the Weibull distribution. Based on the numerical illustrations, It Is shown that the probability of fatigue fat lure and the allowable stress-range for fatigue design could be significantly affected by the presence of residual stresses. This effect may be represented through the mean stress at the welded joints.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.137-143
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• 2012

This study analyzes flywheel through the analyses of stress, fatigue and vibration. Maximum equivalent stress is 15.271MPa at the mid round shape and maximum deformation is 0.02264mm at the outer teeth. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of -$10^4$MPa and the amplitude stress of 1000 to 2900MPa, the possibility of maximum damage becomes 30%. This stress state can be 20 times greater than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The range of natural frequencies becomes 200 to 820Hz and the values of these deformations are not more than 10mm. The structural result of this study can be effectively utilized with the design of flywheel by investigating prevention and durability against its damage.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.95-101
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• 2001

Steel bridges, which have been damaged by load and corrosion, need repair or strengthening. In general, before the repair welding procedure, cutting procedure carry out. Therefore, the investigating of the behavior of stress generated by cutting is so important for safety of structure. Residual stress produced by gas cutting was analyzed using 2D and 3D thermal elasto-plastic FEM. According to the results, the magnitude of temperature was analyzed by 2D-FEM is smaller than that was analyzed using the 3D-FEM program at the start and end edge of flange. And the magnitude and distribution of residual stress of perpendicular to the cutting line was analyzed by the 2D-FEM program was similar to that was analyzed by the 3B-FEM program. Therefore, it is possible to predict of cutting stress by 2D and 3D FEM.