• 한국정밀공학회지
• /
• 제28권11호
• /
• pp.1316-1322
• /
• 2011

Most of the mechanical structures use bolting or spot welding for the whole structure. In recent years, bolting & rivets are used rather than the welding due to reassembly and repair. Analysis of bolted joints is so complicate that many conditions must be considered such as pre-load and contact, etc.. Bolted joint analysis is done by theoretical, experimental & numerical methods. However, numerical analysis in the bolted joint is used because the contact and stress in the joints are changed due to the pre-load. In this study, we analysis the slip and the deformation of the contact area in the joint depending on the pre-load and find the optimized bolting condition.

• 대한기계학회논문집A
• /
• 제21권10호
• /
• pp.1656-1665
• /
• 1997

The intake noise, a major source of vehicle noises, has rapidly become a noticeable, and has been studied to reduce the level. Traditionally, the intake system has been developed through a experiment, namely, the trial and error process. This approach requires very high cost and long time consuming to develop the systm. Recently, FEM and BEM are becoming useful in analysis of the intake system, and the results of analysis are very valid. But because this techniques also require high cost and long analysis time, this technique is generally not practical tool at the early stage of the development. In this study, the software was developed to predict and analyze the acoustic characteristics of the intake system. It was based on the Transfer Matrix Method and operated to analyze a simplified intake system in a personal computer. It can be used early in the design stage of development of the intake system. This study presented a improvement to reduce the level of the intake noise, which modified the specification of the intake system. And the improvement were verified by NIT/SYSNOISE, FE analysis commercial software, and testing a prototype.

• 대한기계학회논문집A
• /
• 제21권10호
• /
• pp.1648-1655
• /
• 1997

The intake noise, a major source of vehicle noises, has rapidly become a noticeable, and has been studied to reduce the level. Traditionally, the intake system has been developed through a experiment, namely, the trial and error process. This approach requires very high cost and long time consuming to develop the system. Recently, FEM and BEM are becoming useful in analysis of the intake system, and te results of analysis are very valid. But because these techniques also require high cost and long analysis time, these are generally not practical tool at the early stage of the development of an intake system. In this study, the software was developed to predict and analyze the acoustic characteristics of an intake system. It was based on the Transfer Matrix Method and operated to analyze a simplified intake system in a personal computer. It can be used early in the design stage of development of the intake system. This study presented an improvement to reduce the level of an intake noise. It was to select the optimum position of a resonator and verified by NIT/SYSNOISE, FE analysis commercial software, and testing a prototype.

• 대한치과기공학회지
• /
• 제33권4호
• /
• pp.307-312
• /
• 2011

Purpose: The purpose of this study is a porous cube mechanical analysis for the dental implant. Methods: The porous cube with a side length of 10mm was designed for dental implant. To choose proper design, porous hexagon with a side 10mm which was drilled as a regular hexagon with diameter 0.8mm, 1.0mm, 1.2mm and a side 0.4mm, 0.5mm, 0.6mm each using Computer AUTO CAD(Autodesk, 2008). Each cube was carried out in the mechanical analysis. Results: The result of mechanical analysis was observed that the H0.8 was minimum stress 0.045068MPa, maximum stress 9.4565MPa and minimum strain $0.00389{\times}10^{-4}Mpa$, maximum strain $0.816{\times}10^{-4}Mpa$, the H1.0 minimum stress 0.001147MPa, maximum stress 9.099MPa and minimum strain $0.000099{\times}10^{-4}Mpa$, the maximum strain $0.784{\times}10^{-4}Mpa$, the H1.2 minimum stress 0.099393MPa, maximum stress 13.137MPa and minimum strain $0.0112{\times}10^{-4}Mpa$, maximum strain $1.13{\times}10^{-4}Mpa$. Conclusion: The mechanical analysis of porous hexahedron was that H1.0 is the best result. It will be applicable to the porous implants.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.975-977
• /
• 2014

Recently, As portability of storage device has been increased, it is important to analyze the precise anti-shock analysis. For non-operational shock analysis, the accuracy of non-operational shock simulation has been improved. However, because operational shock analysis includes nonlinear process, it is hard to get clear result from operational shock simulation. In this paper, by using Lagrange multiplier method, the FE model including ramp-disk contact of nonlinear process will be analyzed. Through this, we find ramp-disk contact affect the dynamic of slider. Additionally, for the more accurate analysis, we should include ramp-disk contact process at the FE model.

• 대한치과기공학회지
• /
• 제33권1호
• /
• pp.55-61
• /
• 2011

Purpose: In this study, FEM(Finite Element Method) and bending strength test was conducted using normal implant and porous implant for the mechanical estimation of porous dental implant made by SLM method. Methods: Mechanical characteristics of PI(porous implant) and NI(normal implant) applied distributed loads(200N, 500N) were observed through FEM analysis. And each bending strength was gotten through bending test using MTS(Mechanical Test System, Instron 8871). Results: The result of FEM analysis was observed that stress difference between upper and surface of PI was 12 times, while NI was 2 times. The result of bending test was observed that bending strength of PI was lower than NI. we made a decision about this result that cross-sectional area of NI was larger than the PI. Conclusion: The stress shielding ability of porous implant was better than normal implant through result of FEM analysis. And bending strength of porous implant was lower than NI. We think that cause of this result was difference of cross-sectional area.

• Nuclear Engineering and Technology
• /
• 제51권6호
• /
• pp.1658-1668
• /
• 2019

Nuclear power generates a large portion of the energy used today and plays an important role in energy development. To ensure safe nuclear power generation, it is essential to conduct an accurate analysis of reactor structural integrity. Accordingly, in this study, a methodology for obtaining accurate structural responses to the combined seismic and reactor coolant loads existing prior to the shutdown of a nuclear reactor is proposed. By applying the proposed analysis method to the reactor vessel internals, it is possible to derive the seismic responses considering the influence of the hydraulic loads present during operation for the first time. The validity of the proposed methodology is confirmed in this research by using the finite element method to conduct seismic and hydraulic load analyses of the advanced APR1400 1400 MWe power reactor, one of the commercial reactors. The structural responses to the combined applied loads are obtained using displacement-based and stress-based superposition methods. The safety of the subject nuclear reactor is then confirmed by analyzing the design margin according to the American Society for Mechanical Engineers (ASME) evaluation criteria, demonstrating the promise of the proposed analysis method.

• Journal of Power Electronics
• /
• 제19권1호
• /
• pp.24-33
• /
• 2019

A new modeling method for AC-AC switched capacitor converters (SCCs) is introduced in this study. The proposed analytical method aims to accurately describe the input-output characteristics of AC-AC SCCs and establish a mathematical model for static voltage conversion ratio and equivalent resistance, which are key performance metrics for SCCs. A quantitative analysis of converter regulation capability is addressed on the basis of the modeling method. In this analysis, the effects of the control parameters and individual components on SCCs are illustrated extensively. Component stresses, such as the peak value and transient variation of the voltage/current of the converter, are also presented. The effectiveness of the proposed method is verified by comparing it with the existing modeling method and applying it to an AC-AC SCC with a conversion ratio of three. Two 1 kW prototypes are built in a laboratory, and their experimental results exhibit good agreement with the theoretical analysis.

• Structural Engineering and Mechanics
• /
• 제82권3호
• /
• pp.271-282
• /
• 2022

The active learning surrogate model based on adaptive sampling strategy is increasingly popular in reliability analysis. However, most of the existing sampling strategies adopt the trial and error method to determine the size of the Monte Carlo (MC) candidate sample pool which satisfies the requirement of variation coefficient of failure probability. It will lead to a reduction in the calculation efficiency of reliability analysis. To avoid this defect, a new method for determining the optimal size of the MC candidate sample pool is proposed, and a new structural reliability analysis method combining polynomial chaos-based Kriging model (PC-Kriging) with adaptive sampling region is also proposed (PCK-ASR). Firstly, based on the lower limit of the confidence interval, a new method for estimating the optimal size of the MC candidate sample pool is proposed. Secondly, based on the upper limit of the confidence interval, an adaptive sampling region strategy similar to the radial centralized sampling method is developed. Then, the k-means++ clustering technique and the learning function LIF are used to complete the adaptive design of experiments (DoE). Finally, the effectiveness and accuracy of the PCK-ASR method are verified by three numerical examples and one practical engineering example.

• Computers and Concrete
• /
• 제32권6호
• /
• pp.595-606
• /
• 2023

Dune sand (DS) has been widely used as a partial replacement for regular sand in concrete construction. Therefore, investigating its mechanical properties is critical for the analysis and design of structural elements using DS as a construction material. This paper presents a comprehensive investigation of the mechanical properties of DS concrete, considering different replacement ratios and strength grades. Regression analysis is utilized to develop strength prediction models for different mechanical properties of DS concrete. The proposed models exhibit high calculation accuracy, with R² values of 0.996, 0.991, 0.982, and 0.989 for cube compressive strength, axial compressive strength, splitting tensile strength, and elastic modulus, respectively, and an error within ±20%. Furthermore, a stress-strain relationship specific to DS concrete is established, showing good agreement with experimental results. Additionally, nonlinear finite element analysis is performed on concrete-filled steel tube columns incorporating DS concrete, utilizing the established stress-strain relationship. The analytical and experimental results exhibit good agreement, confirming the validity of the proposed stress-strain relationship for DS concrete. Therefore, the findings presented in this paper provide valuable references for the design and analysis of structures utilizing DS concrete as a construction material.