This paper reports the results of an experimental examination using X-rays to test annealing materials for lapped bearing steel (STB2), to confirm the validity of the weighted averaging analysis method. The distribution behavior for the sin diagram and the presence or absence of differences in the peak method, half-value breadth method, and centroid method were investigated. When lapping the annealed bearing steel (STB2) material, a residual stress state with a non-directional steep gradient appeared in the surface layer, and it was found that the weighted averaging analysis method was effective. If there is a steep stress gradient, the sin diagram is curved and the diffraction intensity distribution curve becomes asymmetric, resulting in a difference between the peak method, half-value breadth method, and centroid method. This phenomenon was evident when the stress gradient was more than 2~3 kg/mm2/μm. In this case, if the position of the diffraction line is determined using the centroid method and the weighted averaging analysis method is applied, the stress value on the surface and the stress gradient under the surface can be obtained more accurately. When the stress gradient becomes a problem, since the curvature of the sin diagram appears clearly in the region of sin > 0.5, it is necessary to increase the inclination angle  as much as possible. In the case of a lapping layer, a more accurate value can be obtained by considering  in the weighted averaging analysis method. In an isotropic biaxial residual stress state, the presence or absence of  can be determined as the presence or absence of strain for sin≈0.4.

Application of a very high internal pressure on the thick-walled pressure vessel induces beneficial compressive tangential residual stresses near the bore of the pressure vessel after unloading the internal pressure. However, a reverse yielding due to the Bauschinger effect during the unloading process causes the reduction of the compressive residual stress near the bore. In order to evaluate the autofrettage residual stress distributions of the thick-walled pressure vessel, the Bauschinger effects were considered. Magnitudes of the compressive residual stresses at the bore determined by considering the Bauschinger effects decreased by about 25 percent, compared to the case of linear elastic unloading, i.e., without Bauschinger effects. Measured residual stress distributions agreed fairly well with the calculated distributions considering the Bauschinger effects.

이 연구는 탄소섬유시트의 보강겹수에 따른 I형 PFRP 휨부재의 휨보강 효과를 조사하기 위해 길이 600mm의 PFRP 휨부재와 상하부 플랜지에 1mm 두께의 탄소섬유시트로 보강하여 휨실험을 수행하였다. 또한, 탄소섬유시트의 보강겹수와 보강 위치에 따른 I형 PFRP 휨부재의 휨보강 효과와 단면 감소량에 대해 조사하였다. 그 결과 2겹으로 보강하였을 때 휨강도와 휨강성이 증가함을 확인하였다.

The objective of this study is to find the optimal production process in the aluminum IMS core parts. To reduce the production process, the total stage was designed at a total of 2 stages and 3 stages. In the total 2 stages process, the production stage was divided into a shaft part production and a yoke part production. In the total 3 stages process, the yoke production stages were subdivided into the 2 stages for distributing the stress. The results were compared and analyzed in terms of effective stress, folding characteristics and load characteristics. The stress distributions according to the production total stages were almost the same, the yoke production stage was received high stress due to the high strain. Both the tubular shaft yoke and solid shaft yoke according to the production total stages did not have any problems in the production because there did not occur the folding, metal flow and under-fill. When the total 2 stages were employed, the load for producing the tubular shaft yoke and the solid shaft yoke was decreased by 35.0% and 27.1%, respectively. As the results, when the total 2 stages process is applied rather than 3 stages process, the product is produced quickly and it is expected to be advantageous for the production cost due to the low load.

In this analysis, the analytical model was verified through the normal mode analysis of the piston for the 2.9 liter IDI (indirect injection) engine. Heat transfer analysis was carried out by selecting two cases of applied temperature using the validated model. The first case was a condition of 350℃ on the piston upper surface and 100℃ on the piston body and inner wall. In the second case, the conditions were set to give a temperature of 400℃ on the upper surface of the piston and 100℃ on the piston body and the inner wall. In addition, the temperature distribution due to heat transfer was obtained for the pistons with boundary conditions of two cases, and then the thermal stress distribution due to thermal expansion was obtained using the input. Using this analysis result, the thermal stress caused by thermal expansion due to the thermal conduction of the piston is examined and used as the basic data for design.

The objective of this study is to optimize the diameter of tubular shaft yoke and solid shaft yoke, which are the core components of Al IMS for xEV. The processes of both products were designed totally 6 steps to manufactured the shaft part and the yoke part. The diameter of solid shaft yoke and tubular shaft yoke were changed from 20mm to 25mm and from 30mm to 35mm, respectively. Al 6082 was applied to the material of both products. The friction condition between die and material was employed Oil_Cold (Aluminum) with reference to the library in the program. The results were analyzed and compared in terms of effective stress, effective strain, and nodal velocity characteristics. The effective strain value for manufacturing the yoke part was higher than the shaft part because its part has a complex geometry. The value of nodal velocity was also higher with high effective strain region. However, in 6 stage process of tubular shaft yoke, although it had the high effective strain value, the nodal velocity value was the lowest due to the piercing process. The effect of shaft part diameter on effective stress in the tubular shaft was difficult to observe, however, in the solid shaft yoke, when the shaft part of one increased, the effective stress value was increased due to the larger yoke size.

The objective of this numerical study is to investigate the effect of aluminium material on the weight reduction in tubular shaft yoke and solid shaft yoke. The tubular shaft and the solid shaft were designed by 6 stage processes and the results were analyzed by using a finite element analysis method. The coefficient of friction was set to Oil_cold as referred to the analysis library. It was found that the weight was reduced as 65% with applying the aluminium alloy due to lower density than carbon steel. Von-mises stress values of applying aluminium alloy to the tubular shaft yoke and solid shaft yoke were lower than those of carbon steel because of the low yield stress of aluminium alloy. The folding and underfill phenomenon were not observed on the aluminium alloy in tubular shaft yoke and solid shaft yoke. From these results, the weight reduction of products and the extend life of dies can be expected when aluminium alloy is applied.

The objective of this study is to investigate the effect of torque variation on stress distributions in A-IMS module with both side tubular shaft yoke by numerically. In order to achieve this, the torque value was increased from 10Nm to 40Nm, and the results of this work were confirmed in terms of Von-mises Stress and the displacement characteristics. As the torque in module assembly was increased, the stress in tubular shaft york and splined shaft york was increased linearly. The indentation due to the steel ball was occurred in over 40N·m torque which is over the yield strength condition. The largest displacement occurred in the tubular shaft yoke 1, however, it does not exceed the yield strength and is supposed to be restored due to the elasticity. Therefore, it was concluded that there is no problem for the manufacturing of A-IMS with both side tubular shaft yoke.

In this paper, four point bending tests were carried out to analyse flexural strengthening effect by CFRP (Carbon Fiber Reinforced Polymer) layers for I shape PFRP (Pultruded Fiber Reinforced polymer) flexural member retrofitted with CFRP sheet. Comparing load-displacement relation and sectional stress distribution, the flexural strengthening effect by the number of CFRP layers was founded.

PURPOSES : The purpose of this study is to investigate the stresses of the middle slab in a double-deck tunnel owing to the slab lift to replace the underlying elastic pads during maintenance workMETHODS: The middle slab was divided into three different sections: typical section, expansion joint section, and emergency passageway section. Finite element analysis models of these three sections of middle slab were developed, and the stress distribution and maximum stresses were obtained using the models when the middle slab was lifted to replace the underlying elastic pads. Various slab lifting methods were examined in this study such as one-, two-, and multiple-point lifts, distributed lifts, and one or both slab side edge lifts.RESULTS: When the slab side edge is lifted, the longitudinal stresses of the slab are almost the same as the principal stresses. This implies that the governing stresses are the longitudinal stresses. The maximum stresses with both-edge lifts are generally smaller than those with one-edge lifts at all three sections of middle slab.CONCLUSIONS: If the middle slab in a double-deck tunnel is lifted for maintenance, the slab should be lifted at multiple points along the longitudinal direction to reduce the tensile stresses.

Numerical analysis has been performed to investigate the stress distribution characteristics of auxiliary axle system in a compact special vehicle. Structural and running stability of compact special vehicle is largely affected by auxiliary axle system installation. Structural characteristics of stress and deformation distributions with safe factor in the auxiliary axle system are analyzed. It can be seen that maximum stress happens near the local axle position, and deformation is also predicted. Simulation results are also compared with experimental test data. These results from this study could be applicable for optimal design of diverse axle systems in the compact special vehicle.

The object of this study was to investigate for improving of the homogeneous stress distribution according to sliding cage geometry. In order to achieve this, the sliding cage were modelled as type A, type B and type C, then the sliding cage were applied at A-IMS assembly. The numerical simulation was performed by SOLIDWORKS SIMULATION commercial code and the torque range was applied from 10N·m to 40N·m at A-IMS assembly. The results of simulation were compared in terms of Von-mises stress, principal stress and displacement characteristics. Each stress of type B were the highest value. In other hand, Von-mises stress of type A and type C were less than yield stress.

This study was performed for the optimizations of A-IMS assembly by analyzing the stress distributions under the different torque conditions. In order to achieve this, the numerical simulation was performed by SOLIDWORKS commercial code and the torque range that applied on the A-IMS assembly was increased from 10 N·m to 40 N·m. The simulation results were analyzed and compared in terms of Von-mises stress, principal stress, and displacement characteristics. The maximum stress distributions was observed on the contact surface of needle bearing which is located between tubular and solid shaft. It was found that the fracture of A-IMS assembly won’t occur until 30 N·m of torque. Therefore, it was concluded that there is no problem for the manufacturing of A-IMS assembly.

This study investigates area and size of stress part appeared when the continuous loads are applied at artificial joint. Upper and lower parts composed with polyethylene shock absorber and titanium alloy are applied with the loads. The configurations of stress distribution near the hole of support to fix the frame are investigated and secured as through this study. As the result of this study, the stress is concentrated from the edge end of upper artificial joint. The crack is initiated at this point. This analysis result is similar with the instance of tissue corruption due to the damage of artificial joint.

When a bellows is subjected to various deformation conditions such as angular rotation, axial displacement or lateral deflection, the stress is produced at each convolution. These deformations play a significant role in the analysis of strength. Because of geometric complex, it is difficult to analyze the mechanical behavior of bellows. The symmetrical deformation problems of the bellows have been discussed in the study. These problems were investigated by the finite element method. The bellows was meshed with 8 node shell elements and elastic analysis was performed. The mesh consists of 112,800 elements and the lateral deflection from 0 to 21mm, the axial displacement from 0 to 6mm and the angle of rotation from 0 to 0.21 degree was applied at the end cap for the boundary condition. The effects of boundary conditions such as the angle of rotation and the lateral deflection on the stress concentration for the bellows was studied. In addition, the relationship between minimum von-Mises stress and angle of rotation and deflection of bellows was obtained

펄트루젼 FRP 구조용 부재는 많은 유용한 역학적, 물리적 성질 때문에 토목분야에서 구조부재의 매력적인 대체부 재로 고려될 수 있다. 그러나 펄트루젼 FRP는 탄성계수가 상대적으로 낮고, 부재의 단면이 복부와 플렌지 등의 얇 은 판요소로 구성되어 있기 때문에 압축재로 설계할 때 구조적인 안정성은 매우 중요한 고려사항이 된다. 따라서, 압축을 받는 구조용 부재의 설계를 위해, 판요소의 좌굴 및 후좌굴강도를 고려해야 한다. AISC/LRFD의 강구조 설 계기준에서는, 후좌굴강도에 추가적인 단면 내 일정하지 않은 응력분포의 영향을 형상계수(form factor)를 사용하여 고려하고 있다. 이 논문에서는 압축력을 받는 펄트루젼 FRP 구조용 부재의 형상계수를 해석적으로 연구하였으며, 형상계수를 설정하는 과정에 대하여 제안하였다.

콘크리트 포장은 모서리(Edge) 부분에 차량 하중이 작용할 때 큰 응력을 받게 되며 이러한 응력은 포장의 거동 및 장기 공용성에 영향을 미친다. 따라서 본 연구는 콘크리트 포장의 유한요소 모델을 사용하여 콘크리트 포장의 모서리 부분에 복륜 단축, 복륜 복축, 복륜 삼축 등 복륜 다축 하중의 한쪽 차륜이 접하여 작용할 때 포장의 응력 분포와 최대 응력을 분석하기 위하여 수행되었다. 우선 종방향과 횡방향을 따라 응력의 분포 형태를 분석하였고, 콘크리트 슬래브의 두께, 콘크리트 탄성계수, 지반 탄성계수 등이 응력 분포에 미치는 영향을 분석하였다. 또한 하중 접지면적과 연관된 하중 접지압의 변화에 따른 콘크리트 포장의 응력 분포도 분석하였다. 그리고 콘크리트 포장에서 최대 응력이 어느 위치에서 발생하는지에 대한 연구도 수행하였다. 연구 결과 모서리부 하중에 의한 콘크리트 포장의 최대 응력은 콘크리트의 탄성계수가 증가할수록, 슬래브의 두께가 감소할수록, 그리고 지반 탄성계수가 감소할수록 증가하였다. 하중 접지압의 변화에 따른 최대 응력은 콘크리트 탄성계수와 지반 탄성계수의 크기에 따라서는 거의 일정한 변화를 보였으나 슬래브 두께는 얇아질수록 접지압에 따른 최대 응력의 변화가 뚜렷이 보였다. 최대 응력이 생기는 횡방향의 위치는 콘크리트 탄성계수와 지반 탄성계수에는 무관하게 일정하다. 하지만 슬래브의 두께는 두꺼워질수록 최대 응력의 횡방향 상 위치가 모서리에서 내부로 이동한다. 종방향의 최대 응력이 생기는 위치는 단축과 복축 하중일 경우는 축의 위치이며, 삼축 하중일 경우에는 콘크리트 탄성계수나 슬래브 두께가 증가하던지 또는 지반 탄성계수가 감소하면 최대 응력이 생기는 종방향 상 위치가 양쪽 바깥축에서 중간축의 위치로 바뀌게 된다.

평판디스플레이용 진공패널의 제작시 진공으로 유지된 패널을 구성하는 유리판이 받는 응력과 변위를 계산하였다. 유리판의 두께, 패널의 크기 및 실링폭의 크기를 변수로 하여 실제로 진공패널을 제작한 후 패널의 파괴양상과 변위를 측정하였다. 유리판의 파괴양상과 변형측정을 통하여 유리판에 걸리는 최대응력은 테두리부분에 걸리는 것을 확인하였다. 제작된 진공패널이 갖는 응력분포 및 변위의 분포는 패널을 진공실링할 때 사용한 실런트의 폭에 크게 의존하였다. 패널의 실링폭이 커질수록 모서리가 완전 고정된 조건으로 계산한 결과와 유사하였다. 두께가 3mm인 유리판을 사용해서 80×120textrmmm2</TEX> 크기의 패널을 제작할 때 실링폭이 20mm인 경우 측정된 변위는 57μm였으며, 이 값은 모서리가 완전히 고정된 조건으로 계산한 갈인 54μm와 비슷하였다.