• Proceedings of the KSR Conference
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• 2008.11b
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• pp.805-814
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• 2008

This study focused on the resilient modulus prediction model, which is the functions of mean effective principal stress and axial strain, for three types of railroad trackbed materials such as crushed stone, weathered soil, and crushed-rock soil mixture. The model is composed with the maximum Young's modulus and nonlinear values for higher strain in parallel with dynamic shear modulus. The maximum values is modeled by model parameters, $A_E$ and the power of mean effective principal stress, $n_E$. The nonlinear portion is represented by modified hyperbolic model, with the model parameters of reference strain, ${\varepsilon}_r$ and curvature coefficient, a. To assess the performance of the prediction models proposed herein, the elastic response of a test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement during the passages of freight and passenger trains. The material types of sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 0.6mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation.

• 연구논문집
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• s.26
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• pp.33-42
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• 1996

The transmission system of a washing machine which is called by the clutch is one of the most important components to preserve the performance. The clutch housing has a role to guard and mount the transmission system on the frame of the machine. The load which is applied on the clutch housing depends on the operating conditions. Nowadays the dehydration speed is higher and higher in order to improve the efficiency. In this study, the strains on the predicted weak positions were measured using the strain gage and its measuring equipment. The relationships between the dehydration speeds and the maximum principal strains were obtained. Finite element analysis is executed to acquire the effect of the dehydration speed on the stress of the clutch housing. The distributions of the equivalent stress and the maximum stresses under the various speeds, the various loading directions and the various thickness of the clutch housing were obtained.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.121-126
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• 2002

The railroad cars or the commercial vehicles are generally manufactured by the spot welding. Among various kinds of spot welded lap joints, multi-lap joints are one of popular joints in manufacturing their body structures. But, fatigue strength of these joints are lower than that of base metal due to high stress concentration at the nugget edge of the spot weld and are known to considerably be influenced by welding conditions as well as the mechanical and geometrical factors. Thus, it is necessary to establish a reasonable and systematic fatigue design criterion for spot welded multi-lap joints. In this paper, the $\Delta$P-N$_{f}$ curves has been rearranged in the $\Delta$$\sigma$-N$_{f}$ relation with the maximum stress at the nugget edge of spot welded multi-lap joints subjected to tensile shear load. Consequently, the fatigue data were evaluated in terms of fracture mechanics by plotting on the $\Delta$OP-N$_{f}$ curves. From the results obtained, both of them have been revealed to be applicable to fatigue design of spot welded multi-lap joints. However, the fracture mechanical approach is found to be more effective than the maximum stress approach in the range on N$_{f}$$\geq$2x10$^{5}$ . .

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.475-483
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• 2015

PURPOSE. The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS. The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimensional finite element models. Four models were prepared according to different cement types (zinc phosphate, polycarboxylate, glass ionomer, and resin). A load of 700 N was applied vertically on the crowns (8 loading points). Maximum principal stress was determined. RESULTS. Zinc phosphate cement had a greater stress concentration in the cement layer, while polycarboxylate cement had a greater stress concentration on the distal surface of the monolithic zirconia crown and abutment tooth. Resin cement and glass ionomer cement showed similar patterns, but resin cement showed a lower stress distribution on the lingual and mesial surface of the cement layer. CONCLUSION. The test results indicate that the use of different luting agents that have various elastic moduli has an impact on the stress distribution of the monolithic zirconia crowns, cement layers, and abutment tooth. Resin cement is recommended for the luting agent of the monolithic zirconia crowns.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.496-501
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• 2003

Reynolds averaged Wavier-Stokes simulations based on the Reynolds stress model was performed to investigated the effect of inlet flow angle on the distributions of the Reynolds stress tensor inside tip leakage vortex of a linear compressor cascade. Two different inlet flow angles ${\beta}=29.3^{\circ}$(design condition) and $36.5^{\circ}$(off-design condition) were considered. Stress tensor analysis, which transforms the Reynolds stress into the principal direction, was applied to show an anisotropy of the normal stresses. Whereas the anisotropy was highest in the region where the tip leakage vortex collides the suction side of the blade and tip leakage flow enters between blade tip of the pressure side and the endwall, it had the lowest value at the center of tip leakage vortex. It was also found that the magnitude of maximum shear stress at design condition was greater than that of off-design condition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.3
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• pp.290-296
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• 2008

After scientific verification of the osteointegration of dental implants, the overall efficiency of dental implants has been generally accepted. Thus, implants now play a major role in the clinical treatment of an edentulous mandible, and in the prosthetic maintenance equipment for partial edentulous mandible patients. Yet, for the successful long-term maintenance of implants, careful consideration of the bio-mechanics is needed to ensure that the maximum stress in the mandible as a result of chewing is maintained under a critical value. Accordingly, this study focuses on reducing the maximum stresses in an implanted mandible, especially in the cortical bone. Thus, the stresses in the implant and mandible are analyzed using finite element packages, including I-DEAS and NISA II/DISPLAY III, using a local zooming technique for a concentrated stress analysis. In addition, the von-Mises stress and principal stress in the mandible are both checked to determine the best combination.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.5
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• pp.73-85
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• 1999

Yield and fracture are separated in the tensile failure of paper. Failure in the machine direction of photocopy paper is contrasted with failure in the cross-machine direction . The ratios of distortion (shape change) to dilatation (volume change) for individual elements at yield and fracture are described. The ratios of distortion to dilatation are measured and compared to predicted values of the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density factor, samples are prepared from machine direction to cross-machine direction in 15 degree intervals. the strain energy density of individual elements are obtained by the integration of stress from finite element analysis with elastic plus plastic strain energy density theory. Poison's ratio and the angle from the principal material direction have a great effect ion the ratio fo distortion to dilatation in paper. During the yield condition, distortion prevails over dilatation . At fracture, dilatation is at a maximum.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.1-10
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• 2013

Purpose: The purpose of this study was to find an inclination slope of the screw thread that is favorable in distributing the stresses to alveolar bone by using three dimensional finite element analysis. Materials and methods: Three types modelling changed implant thread with fixed pitch of 0.8 mm is the single thread implant with $3.8^{\circ}$ inclination, double thread implant with $7.7^{\circ}$ inclination and the triple thread implant with $11.5^{\circ}$ inclination. And three types implant angulation is the $0^{\circ}$, $10^{\circ}$ and $15^{\circ}$ on alveolar bone. The 9 modelling fabricated for three dimensional finite element analysis that restored prosthesis crown. The crown center applied on 200 N vertical load and $15^{\circ}$ tilting load. Results: 1. The more tilting of implant angulation, the more Von-Mises stress and Max principal stress is increasing. 2. Von-Mises stress and Max principal stress is increasing when applied $15^{\circ}$ tilting load than vertical load on the bone. 3. When the number of thread increased, the amount of Von-Mises stress, Max principal stress was reduced since the generated stress was effectively distributed. 4. Since the maximum principal stress affects on the alveolar bone can influence deeply on the longevity of the implants. When comparing the magnitude of the maximum principal stress, the triple thread implant had a least amount of stress. This shows that the triple thread implant gave a best result. Conclusion: A triple thread implant to increase in the thread slope inclination and number of thread is more effective on the distribution of stress than the single and double thread implants especially, implant angulation is more tilting than $10^{\circ}$ on alveolar bone. Thus, effective combination of thread number and thread slope inclination can help prolonging the longevity of implant.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2037-2047
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• 1991

Strength is not simply a single given value but rather is a statistical one with certain distribution functions. This is because it is affected by many unknown factors such as size, shape, stress distribution, and combined stresses. In this study, a model of loss probability is proposed in view of the fact that one of the fundamental configuration of nature is hexagonal, for example, the shapes of lattice unit, grain, and so on. The model sues the concept of loss of certain element in place of Jayatilaka-Trustrum's length and angle of cracks. Using this model, the loss probability due to each loss of certain elements is obtained. Then, the maximum principal stress is calculated by the finite element method at the centroid of the elements under the tensile load for the 4,095 models of analysis. Finally, the failure probability of the brittle materials is obtained by multiplying the loss probability by the ratio of the maximum principal stress to theoretical tensile strength. Comparison of the result of the Jayatilaka-Trustrum's model and the proposed model shows that the failure probabilities by the two methods are in good agreement. Further, it is shown that the parametric relationship of semi-crack lengths for various degrees of birittleness can be determined. Therefore, the analysis of the failure probability suing the proposed model is shown to be promising as a new method for the study of the failure probability of birttle materials.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.4
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• pp.317-324
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• 2016

Stress tests were conducted in the carbody of the railroad car to check the structural strength of the body of the railroad car. The objective of this study was to evaluate safety of the carbody of a railroad car under the maximal strength. The carbody of rolling stock is a principal structure that supports major equipment of the underframe and the freight. Therefore, the strength evaluation of this structure is important. This study was carried out to analyze the structure of carbody and evaluate safety under maximum vertical load, compressive load, and torsional load. Accordingly, stress tests were conducted on the carbody to measure the stress on each of their parts. Before the load test, a structural-analysis program was used for the stress distribution analysis of the body structure.