• Title/Summary/Keyword: 스트레쳐

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A Study on the Surface Roughness in the A 5032 Sheet Metal Forming (A 5032 판재성형에서 발생하는 표면거칙기에 관한 연구)

  • 박서운;김진무
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.546-551
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    • 1997
  • In sheet metal forming, since the surface area of workpiece is apparently larger than the volume of it, the surface condition of the sheet metal is much varied. The formability of sheet metal is decided by the forming limit and the macroscopic suface defect as like fracture and wrinkle, and microscopic asponent, The factors affected in forming limit are stain herdening exponent, strain-rate scnsitivity exponent, anisotropic coefficient. The increasing of surface roughness is decresed the forming limit curve. It is known that the greater plastic deformation the more surface roughness by Kienzle, Osadaka. The purpose of this study is to investigate the influences of surface roughness in a uniaxial tension and the traperzoidal-shaped box drawing.

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Optimal Shape Design of Legs and Stretcher Parts of Chair (의자 다리와 스트레쳐를 중심으로 한 형상 최적화 설계)

  • Lee, Young-Min;Jeong, Hoon
    • Proceeding of EDISON Challenge
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    • 2016.03a
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    • pp.256-261
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    • 2016
  • In this paper, Shape optimal design for a chair with 4 legs and 2 stretchers consisting of stainless steel was conducted. The shape was transformed by identifying stress and deformation for the part of leg and stretcher. In addition, load condition and mesh was designed using Hypermesh. The stress analysis was carried out using CSD_Elast that is one of EDISON program. In seat test, Maximum equivalent stress was showed at the contact part between seat and legs. As a result, a leg cross-section with rectangular and arch was designed. And optimal height of stretcher was found to reduce a deformation. Also, maximum deformation was reduced by designing a stretcher with ellipse cross-section. So, Optimal chair having 4 legs with rectangular cross section and 2 stretchers with ellipse cross section was shown to satisfy the safety ratio.

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Case Study on Fracture Type of Wooden Crib Wall (목재 Crib wall의 파괴유형에 대한 사례연구)

  • Shin, Changgun;Paik, Moonyeol;Hong, Cheolhwa;Bae, Wooseok
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.7
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    • pp.39-50
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    • 2013
  • Crib wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall. In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall. Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall. Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall. However, in the wooden crib wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling. In this study, it was analyzed fracture types and causes of wooden crib wall through detailed investigation and analysis of a large crib wall construction site. As a results, it occurred the damage in the members of 5.7% in a total of 2,315 locations and the damage of header occurred in the members of a header 80.2%. The 65.7% of the damaged header are concentrated in the lower part of crib wall. Therefore, it was analyzed the differences of fracture types and causes of wooden crib wall depending on the installation position and the kinds of members. It is considered basically the members of various forms of distortion and the grain affecting.

A Study on the Deformation Behavior of the Segmental Grid Retaining Wall Using Scaled Model Tests (조립식 격자 옹벽의 변형거동에 관한 모형실험 연구)

  • Bae, Woo-Seok;Kwon, Young-Cheul;Kim, Jong-Woo
    • Tunnel and Underground Space
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    • v.17 no.5
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    • pp.350-359
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    • 2007
  • Most large cut slopes of open pit mines, roadways, and railways are steeply inclined and composed with rocks that do not contain soils. However, these rock slopes suffer both weathering and fragmentation. In the case of steep slopes, falling rock and collapse of a slope may often occur due to surface erosion. Cast-in place concrete and rubble work are the most widely used earth structure-based pressure supports that act as restraints against the collapse of the rock slope. In order to overcome the shortcomings of conventional retaining walls, a segmental grid retaining wall is being used with connects precasted segments to construct the wall. In this study, laboratory model test was conducted to estimate deformation behavior of segmental grid retaining wall with configuration of rear strecher, height and inclination of the wall. In order to examine the behavior characteristics of a segmental grid retaining wall, this research analyzes the aspects of spacial displacement through relative displacement according to change in the inclination of the wall. Also, the walls behavior according to the formation and status of the rear stretcher which serves the role of transferring the load from the header and the stretcher which make up the wall, the displacement of backfill materials in the wall, and the location of the maximum load were surveyed and the characteristics of displacement in the segmental grid retaining wall were observed. The test results of the segmental grid retaining wall showed that there was a sudden increase in failure load according to the decrease in the wall's height and the size of the in was greatly decreased. Furthermore, it revealed that with identical inclination and height, the structure of the rear stitcher did not greatly affect the starting point or size of maximum horizontal displacement, but rather had a stronger effect on the inclination of the wall.