• Title, Summary, Keyword: Stress Concentration

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A Study on Stress Analysis of Orthotropic Composite Cylindrical Shells with a Circular or an Elliptical Cutout

  • Ryu, Chung-Hyun;Lee, Young-Shin;Park, Myoung-Hwan;Kim, Young-Wann
    • Journal of Mechanical Science and Technology
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    • v.18 no.5
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    • pp.808-813
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    • 2004
  • The stress analysis on orthotropic composite cylindrical shells with one circular or one elliptical cutout subjected to an axial force is carried out by using an analytical and experimental method. The composite cylindrical shell governing equation of the Donnell's type is applied to this study and all results are presented by the stress concentration factor. The stress concentration factor is defined as the ratio of the stress on the region around a cutout to the nominal stress of the shell. The stress concentration factor is classified into the circumferential stress concentration factors and the radial stress concentration factors due to the cylindrical coordinate of which the origin is the center of a cutout. The considered loading condition is only axial tension loading condition. In this study, thus, the maximum stress is induced on perpendicular region against axial direction, on the coordinate. Various cutout sizes are expressed using the radius ratio, (equation omitted), which is the radius of a cutout over one of the cylindrical shell. Experimental results are obtained using strain gages, which are attached around a cutout of the cylindrical shell. As the result from this study, the stress concentration around a cutout can be predicted by using the analytical method for an orthotropic composite cylindrical shell having a circular or an elliptical cutout.

Effect of Cutout Orientation on Stress Concentration of Perforated Plates with Various Cutouts and Bluntness

  • Woo, Jin-Ho;Na, Won-Bae
    • International Journal of Ocean System Engineering
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    • v.1 no.2
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    • pp.95-101
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    • 2011
  • Perforated plates with cutouts (or holes) are widely used in structural members. These cutouts provide stress concentration in plates. Extensive studies have been carried out on stress concentration in perforated plates, which consider cutout shapes, boundary conditions, bluntness of cutouts, and more. This study presents stress concentration analyses of perforated plates with not only various cutouts and bluntness but also different cutout orientations. Especially, the effect of cutout orientation on stress concentration is emphasized since structural members have become more complicated recently. To obtain stress concentration patterns, a finite element program, ANSYS, is used. For the designated goal, three parameters are considered as follows: the shapes of polygonal cutouts (circle, triangle, and square), bluntness (a counter measure of radius ratio, r/R), and rotation of cutouts (${\theta}$). From the analyses, it is shown that, in general, as bluntness increases, the stress concentration increases, regardless of the shape and rotation. A more important finding is that the stress concentration increases as the cutouts become more oriented from the baseline, which is the positive horizontal axis (+x). This fact demonstrates that the orientation is also a relatively significant design factor to reduce stress concentration. In detail, in the case of the triangle cutout, orienting one side of the triangle cutout to be perpendicular to the applied tensile forces is preferable. Similarly, in the case of the square cutout, it is more advantageous to orient two sides of square cutout to be perpendicular to the applied tensile force. Therefore, at the design stage, determining the direction of a major tensile force is required. Then, by aligning those polygon cutouts properly, we can reduce stress concentration.

A Study on Stress Concentration Alleviation at Pipe Connections (관로 연결부의 응력집중저감기법연구)

  • Chung, So-Young;Han, Taek-Hee;Han, Keum-Ho;Kang, Young-Jong
    • 한국방재학회:학술대회논문집
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    • pp.289-292
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    • 2007
  • Stress concentration have a effect on commission of structures and sometimes it cause the fracture of structures. Stress concentration is appeared where have a sudden section change like pipe connections. So stress concentration is a potent influence at pipe connentions. This paper make a study of pipe connections to alleviate stress concentration, and propose the stress concentration alleviation method that will make better efficient pipe system and will have a good effect on economic, social aspect.

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A Study on the Stress Concentration Coefficient due to the Change of Position and Shape of Ellipse on a Square Plate (사각 평판에서 타원의 위치와 형상 변화에 따른 응력집중계수의 변화에 관한 연구)

  • 최경호;권영석;박기훈;김현수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.833-836
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    • 2002
  • Sometimes open holes are required for the function and the weight reduction of structure and machinery. However, the serious stress concentration occurs because of the geometric discontinuity caused by the holes and cutting section. In this study, it is attempted to obtain the stress concentration coefficients of the inner surface of the hole boundary by changing the position and the shape of holes on the homogeneous isotropic plate. And the effects on the plate are investigated. The results show that the stress level becomes low and the distribution area widens the position of stress concentration changes as the ratio ah increases and change to a circle. And as the ratio a/l decreases, the stress concentration reduces.

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Analysis & Comparison of Stress Concentration Factors of 2D Plate with Single/Multiple Hole (2차원 평판 단일/다중 구멍에 대한 응력 집중 계수 해석 및 비교)

  • Lee, SangGu;Gong, DuHyun;Sim, JiSoo;Shin, SangJoon
    • Proceeding of EDISON Challenge
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    • pp.209-216
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    • 2016
  • Holes of rivets, bolts and nuts may cause stress concentration on the plates used in aircraft, ship and other structures. Excessive stress concentration may lead to severe breakage of the plates. Thus, accurate analysis of the stress concentration at the design stage will be important. In this paper, accuracy of EDISON program in stress concentration analysis was examined. By changing hole size on a narrow plate, the change of the stress concentration factor(K) was investigated. Additionally, the same experiment was conducted about series of holes on plate to investigate the interaction between adjacent holes. Then, these numerical results were compared with the analytic prediction. EDISON program showed very high accuracy about stress concentration, since the numerical results was correlated well with the analytic prediction.

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A Study on the Effect of Stress Concentration Factor Determined by 3D-ESPI System on the Fatigue Life (3D-ESPI 시스템을 이용하여 결정된 응력집중계수가 피로수명에 미치는 영향에 관한 연구)

  • 김경수;심천식
    • Journal of Ocean Engineering and Technology
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    • v.16 no.1
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    • pp.46-51
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    • 2002
  • Fatigue life estimation by the theoretical stress concentration factors are, in general, considerably different from test results. And in calculating stress concentration factor, it is very difficult to consider actual geometry and material property which are the notch shapes, imperfections or defects of materials such as porosities inclusions and casting defects, etc. Therefore, the paper deals with the experimental method to find out the more exact stress concentration factors by measuring the strain distributions on each specimen by 3D-ESPI(Electronic Speckle Pattern Interferometry) System. Then the fatigue lives are compared between theoretical calculations using stress concentration factors determined by 3D-ESPI system and fatigue test results.

Field Test Study on Stress Concentration Ratio of Composited soft ground with Crushed-stone Compaction Pile (쇄석다짐말뚝 복합지반의 응력분담에 관한 현장실험 연구)

  • 김태훈;이민희;최용규
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.717-724
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    • 2003
  • Although sand compaction pile is applied considerably for increase of hearing capacity in domestic, it is getting more necessary to develope the alternative materials because of exhaustion and increase of unit cost of sand. In this study, stress concentration ratio between crushed-stone pile and soft ground was measured and, a displacement ratio 30, 40 and 50%, variation of stress concentration ratio was analyzed. As an increase displacement ratio, the stress concentration effect of crushed-stone compaction pile doesn't increase proportionally and effect of ground improvement in case of ground was good at displacement ratio 30% or 40%. The stress concentration ratio of crushed-stone compaction pile in group piles is 1.5 times that of crushed-stone compaction pile in single pile.

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A Numerical Analysis for the Influential Factors on the Stress Concentration Ratio (모래다짐말뚝지반의 응력분담비에 영향을 미치는 인자에 대한 해석적 연구)

  • Choi, Hyo-Won;Shin, Hyun-Young;Yoo, Han-Kyu;Kim, Soo-Sam
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.966-973
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    • 2005
  • The stress concentration ratio in accordance with area replacement ratios were considered as core elements of design. However, the stress concentration ratio will be vary depends on progress of consolidation in clay ground. And, since it is not sure to know the affecting factors accurately, the value is decided based on field experiences. To use SCP method more effective and correspond to soil improvement, the decision on proper area replacement ratio through the exact stress concentration ratio is very important. Accordingly, a numerical analysis on influence of various factors that needed to make rational designing guide for decision of proper area replacement ratio to stress concentration ratio was executed in this study.

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A Study on the Stress Concentration Phenomenon of a Dissimilar Joints (이종재 접합부에서의 응력집중현상에 관한 연구)

  • 조상명;김영식
    • Journal of Welding and Joining
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    • v.10 no.1
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    • pp.35-42
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    • 1992
  • In this study, the stress concentration phenomenon for the dissimilar joints(ceramic-metal) bonded by thermal treating using a soft-insert metal(copper) was investigated with the aid of FEM(finite element method) under the load condition of uniform tension. The analysis was carried out by the supposing that stress states are plane stress or plane strain and elastic or elastic-plastic. And the Von Mises yield criterion and the incremental theory as plastic flow were adopted in this analysis. As the summarized results obtained, the stress concentration phenomenon was severer as the soft insert metal was thicker, in plane strain than in plane stress and in elastic-plastic state than in elastic state. Furthermore, the inducing mechanism of stress concentration was well expressed by the constraint forces(Fc) generated between the soft and the hard material.

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Estimation of stress concentration factor in bolt jointed structure with variable preload (체결력에 따른 볼트 결합구조물의 응력집중계수 평가)

  • 송준혁
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.298-303
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    • 1998
  • Most of mechanical structures are combined of substructures such as beam and/or plates. There are few system with unibody structures but are not a few systems with united body structures. Generally the dynamic analysis of whole structures is perform ed under alternating load. However, the analysis of each joint area is more important than others for zero severity. This paper presents the results of analysis of concentration stress in bolt jointed structure with variable preload. At frist, a static vibration test was performed to find out a nominal stress of bolt joint ed plates from the relationship between natural frequency and nominal stress. Then a concentration stress was computed at contact point between bolt and plate in the structure. It is believed that the proposed method has promising implications for safer design with fatigue quality index of stress concentration factor and has merit for cost down and saving time at the beginning of vehicle development.

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