• Title/Summary/Keyword: deformed shape

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A Simple Finite Element Method to Determination of Deformed Shape and Load-Displacement Curve of Elastomers (방진고무 변형형상 및 하중-변위곡선 예측을 위한 단순 유한요소법)

  • Jeon, Man-Su;Mun, Ho-Geun;Kim, Seong-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.2
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    • pp.217-222
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    • 1997
  • A simple finite element approach to predicting deformed shape and load-deflection curve of elastomers is presented in this paper. The method is based on several simplifications in deformation pattern and material behavior. The conventional updated Lagrangian approach is employed together with material data obtained by a simple tension test. The presented approach is verified through comparison of predicted results with experimental ones and applied successfully to shape design of various elastomers for shock, vibration and noise control. The advantage of the presented approach lies in easiness, simplicity and accuracy enough for engineering application.

Optimum design of a pilger mill process for wire forming using CAD/CAE (CAD/CAE를 이용한 세선 성형용 필거밀 공정의 최적설계)

  • 정용수;박훈재;김승수;나경환;이형욱;한창수
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.84-88
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    • 2003
  • In this paper, The optimum design of a die shape has been carried out the FEM analysis of a pilger mill process considering various factors. The pilger mill forming process consists of a pair of rotating die which has appropriate surface shape. The important design parameters of the pilger mill are the feed rate and the profile of grooved die. Optimum design procedure was performed in order to investigated effects on the forming load and the deformed shape of material depending on the die radius profile. Profile of the die surface for the optimum design were suggested with the linear, the cosine and the quadratic curve considering a physical forming process. The surface of each die was modeled using the 3DAutoCAD and the analysis of pilger forming process was performed using the LS-DYNA3D. The optimum profile of the die shape for the pilger mill was determined to the quadratic profile. Since the analysis results provide that the model of the quadratic profile gives the lowest forming load and a proper deformed shape.

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A Robust Algorithm for Tracking Non-rigid Objects Using Deformed Template and Level-Set Theory (템플릿 변형과 Level-Set이론을 이용한 비강성 객체 추적 알고리즘)

  • 김종렬;나현태;문영식
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.40 no.3
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    • pp.127-136
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    • 2003
  • In this paper, we propose a robust object tracking algorithm based on model and edge, using deformed template and Level-Set theory. The proposed algorithm can track objects in case of background variation, object flexibility and occlusions. First we design a new potential difference energy function(PDEF) composed of two terms including inter-region distance and edge values. This function is utilized to estimate and refine the object shape. The first step is to approximately estimate the shape and location of template object based on the assumption that the object changes its shape according to the affine transform. The second step is a refinement of the object shape to fit into the real object accurately, by using the potential energy map and the modified Level-Set speed function. The experimental results show that the proposed algorithm can track non-rigid objects under various environments, such as largely flexible objects, objects with large variation in the backgrounds, and occluded objects.

Displacement tracking of pre-deformed smart structures

  • Irschik, Hans;Krommer, Michael;Zehetner, Christian
    • Smart Structures and Systems
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    • v.18 no.1
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    • pp.139-154
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    • 2016
  • This paper is concerned with the dynamics of hyperelastic solids and structures. We seek for a smart control actuation that produces a desired (prescribed) displacement field in the presence of transient imposed forces. In the literature, this problem is denoted as displacement tracking, or also as shape morphing problem. One talks about shape control, when the displacements to be tracked do vanish. In the present paper, it is assumed that the control actuation is provided by imposed eigenstrains, e.g., by the electric field in piezoelectric actuators, or by thermal actuators, or via analogous physical effects, such as magneto-striction or pre-stress. Structures with a controlled eigenstrain-type actuation belong to the class of smart structures. The action of the eigenstrains can be conveniently characterized by actuation stresses. Our theoretical derivations are performed in the framework of the theory of small incremental dynamic deformations superimposed upon a statically pre-deformed configuration of a hyperelastic solid or structure. We particularly ask for a distribution of incremental actuation stresses, such that the incremental displacements follow exactly a prescribed trajectory field, despite the imposed incremental forces are present. An exact solution of this problem is presented under the assumption that the actuation stresses can be tailored freely and applied everywhere within the body. Extending a Neumann-type solution strategy, it is shown that the actuation stresses due to the distributed control eigenstrains must satisfy certain quasi-static equilibrium conditions, where auxiliary body-forces and auxiliary surface tractions are to be taken into account. The latter auxiliary loading can be directly computed from the imposed forces and from the desired displacement field to be tracked. Hence, despite the problem is a dynamic one, a straightforward computation of proper actuator distributions can be obtained in the framework of quasi-static equilibrium conditions. Necessary conditions for the functioning of this concept are presented. Particularly, it must be required that the intermediate configuration is infinitesimally superstable. Previous results of our group for the case of shape control and displacement tracking in linear elastic structures are included as special cases. The high potential of the solution is demonstrated via Finite Element computations for an irregularly shaped four-corner plate in a state of plain strain.

Improved deformation energy for enhancing the visual quality of planar shape deformation (평면 형상 변형의 시각적 품질 향상을 위한 개선된 형상 변형 에너지)

  • Yoo, Kwangseok;Choi, Jung-Ju
    • Journal of the Korea Computer Graphics Society
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    • v.18 no.4
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    • pp.1-8
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    • 2012
  • We present improved deformation energy to enhance the visual quality of a shape deformation technique, where we preserve the local structure of an input planar shape. The deformation energy, in general, consists of several constraints such as Laplacian coordinate constraint to preserve the quality of deformed silhouette edges, mean value coordinates and edge length constraints to preserve the quality of deformed internal shape, and user-specified position constraints to control the shape deformation. When the positions of user-specified vertices change, shape deformation techniques compute the positions of the other vertices by means of nonlinear least squares optimization to minimize the deformation energy. When a user-specified vertex changes its position rapidly, it is frequently observed that the visual quality of the deformed shape decrease rapidly, which is mainly caused by unnecessary enlargement of the Laplacian vectors and unnecessary change of the edge directions along the boundary of the shape. In this paper, we propose improved deformation energy by prohibiting the Laplacian and edge length constraints from changing unnecessarily. The proposed deformation energy incorporated with well-known optimization technique can enhance the visual quality of shape deformation along the silhouette and within the interior of the planar shape while sacrificing only a little execution time.

Fast Planar Shape Deformation using a Layered Mesh (계층 메쉬를 이용한 빠른 평면 형상 변형)

  • Yoo, Kwang-Seok;Choi, Jung-Ju
    • Journal of the Korea Computer Graphics Society
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    • v.17 no.3
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    • pp.43-50
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    • 2011
  • We present a trade-off technique for fast but qualitative planar shape deformation using a layered mesh. We construct a layered mesh that is embedding a planar input shape; the upper-layer is denoted as a control mesh and the other lower-layer as a shape mesh that is defined by mean value coordinates relative to the control mesh. First, we try to preserve some shape properties including user constraints for the control mesh by means of a known existing nonlinear least square optimization technique, which produces deformed positions of the control mesh vertices. Then, we compute the deformed positions of the shape mesh vertices indirectly from the deformed control mesh by means of simple coordinates computation. The control mesh consists of a small number of vertices while the shape layer contains relatively a large number of vertices in order to embed the input shape as tightly as possible. Since the time-consuming optimization technique is applied only to the control mesh, the overall execution is extremely fast; however, the quality of deformation is sacrificed due to the sacrificed quality of the control mesh and its relativity to the shape mesh. In order to change the deformation behavior and consequently to compensate the quality sacrifice, we present a method to control the deformation stiffness by incorporating the orientation into the user constraints. According to our experiments, the proposed technique produces a planar shape deformation fast enough for real-time applications on limited embedded systems such as cell phones and tablet PCs.

Vertebral abnormality in Hatchery-reared Black Sea Bream (Acanthoparus schlegelii) fingerlings (인공종묘 생산 감성돔 (Acanthoparus schlegelii) 치어의 척추 변형에 관하여)

  • Park, Sung-Woo;No, Yun-San;Yu, Jin-Ha;Kim, Jin-Do
    • Journal of fish pathology
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    • v.21 no.2
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    • pp.139-148
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    • 2008
  • Vertebral deformity in hatchery-reared black sea bream (Acanthoparus schlegelii) fingerlings occurred. Deformed fish had a good appetite but no clinical signs were found except the vertebral abnormality and darkness around the dorsal skin of the deformed vertebra. As more than 90% of the hatchery-reared fish exhibited vertebral abnormality, the fingerlings could not be used for commercial seeds any more. No morphological change in the swim bladder was observed. Histopathological changes on the deformed vertebra, gill, liver, and spleen were observed to clarify the cause of the deformity. The vertebra were irregularly deformed upward with the shape of "V" in an alphabetic character causing the spinal cord and dorsal aorta suppressed. The diameters of the muscle fibers around the deformed vertebra, especially, in the dorsal part, were much smaller and more irregular than those in normal fish, and the gabs between the fiber bundles were enlarged. No evidence of inflammatory responses in the lateral musculature were found. On the basis of normal inflation of the swim bladder, cultural environments for growth of the fingerlings, and histopathological alterations in the muscle, vertebra and gills, it is suggested that high speed of water current in the culturing aquaria between 23 to 30 days after hatching was responsible for the development of vertebral abnormality.

Shape Recognition of a Cabinet by using Ultrasonic Sensors (초음파 센서를 사용한 캐비닛 형상 인식)

  • Park, Sang-Sin;Sung, Young-Whee;Kim, Dong-Hyeon
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.48 no.4
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    • pp.10-16
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    • 2011
  • A cabinet is an outer frame of a TV, which is usually made of poly-carbonate. Cabinets are apt to be deformed because of applied heat during injection molding process and UV joining process. Severely deformed cabinets cause a falling-off in quality of the final product. Therefore cabinets should be inspected and only the good ones should be delivered to the following process. We implemented an experimental system for shape recognition of a cabinet and proposed several indices to characterize the shape of a cabinet. We also proposed algorithms to eliminate the possible bias present in measured data and to check the goodness of a cabinet. Experimental results show the feasibility of the propose algorithms.

Analysis of Free Forging of Cylindrical Billets by Using finite Element Method (유한요소법을 이용한 원통형 강편의 자유단조 해석)

  • 정동원
    • Journal of Ocean Engineering and Technology
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    • v.16 no.6
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    • pp.49-54
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    • 2002
  • The Finite Element Method is applied to the determination of the deformed bulge profile and strain distribution during upset forming of cylindrical billets. From the results of simulation, the bulging along the z-axis becomes more severe with increasing eight reduction, and with increasing friction at the die-material interface. The present method can be used for the simple prediction of the deformed shape and strain distribution in upset forging of cylindrical billets with dissimilar fictional conditions at the die-material interfaces.

The Classification of Foot Types of Junior High School Boys for the Development of Shoes' Easy-Order Prototype (신발류 이지오더 Prototype 개발을 위한 청소년의 발의 형태 분류)

  • Lim, Ji-Young;Choi, Sung-Won
    • Fashion & Textile Research Journal
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    • v.7 no.5
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    • pp.535-541
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    • 2005
  • The health of feet is connected with individual's health and affects a man's activity. Shoes need to be designed to protect feet and to absorb the impact of land. In order to choose suitable shoes for feet, the foot size and shape must be considered, so it is essential to grasp the exact size and shape of the foot. This study aims to present fundamental data on shoes' easy order prototype development for choosing shoes of good wearing comfort, by classifying feet size and shape junior high school boys in the early adolescent period. The subject were 234 Korean junior high school boys age from 14 to 16 years old. The subjects were directly measured anthropometrically and indirectly analyzed photographically. 6 factors were extracted through factor analysis and those factors comprised 79.42% of total variance. The factors characterizing foot girth and width, foot length, foot height, foot shape around the fifth toes, angle of foot breadth and foot shape around the first toes. 3 clusters as their foot shape were categorized using 6 factor scores by cluster analysis. Type 1 was characterized by long large foot with deformed first toe. Type 2 had smaller in foot girth, width and length than other types and with deformed fifth toe. Type 3 had average size and high foot shape. Shoes prototype which is to be developed later on will be able to generate 2D flattening in the foot sole form. Therefore, it would be a great support in producing and choosing appropriate shoes if forms are classified by subdividing foot form classification and extract a factor which shows only the foot sole shape.