• Title/Summary/Keyword: additional element

Search Result 692, Processing Time 0.028 seconds

Completeness requirements of shape functions for higher order finite elements

  • Rajendran, S.;Liew, K.M.
    • Structural Engineering and Mechanics
    • /
    • v.10 no.2
    • /
    • pp.93-110
    • /
    • 2000
  • An alternative interpretation of the completeness requirements for the higher order elements is presented. Apart from the familiar condition, $\sum_iN_i=1$, some additional conditions to be satisfied by the shape functions of higher order elements are identified. Elements with their geometry in the natural form, i.e., without any geometrical distortion, satisfy most of these additional conditions inherently. However, the geometrically distorted elements satisfy only fewer conditions. The practical implications of the satisfaction or non-satisfaction of these additional conditions are investigated with respect to a 3-node bar element, and 8- and 9-node quadrilateral elements. The results suggest that non-satisfaction of these additional conditions results in poorer performance of the element when the element is geometrically distorted. Based on the new interpretation of completeness requirements, a 3-node element and an 8-node rectangular element that are insensitive to mid-node distortion under a quadratic displacement field have been developed.

Fatigue study on additional cutout between U shaped rib and floorbeam in orthotropic bridge deck

  • Ju, Xiaochen;Zeng, Zhibin;Zhao, Xinxin;Liu, Xiaoguang
    • Steel and Composite Structures
    • /
    • v.28 no.3
    • /
    • pp.319-329
    • /
    • 2018
  • The field around additional cutout of the floor beam web in orthotropic bridge deck was subjected to high stress concentration, especially the weld toe between floor beam and U shaped rib and the free edge of the additional cutout. Based on different considerations, different geometrical parameters of additional cutout were proposed in European, American and Japanese specifications, and there remained remarkable differences among them. In this study, considering influence of out-of-plane deformation of floor beam web and U shaped rib, parameter analysis for additional cutout under typical load cases was performed by fine finite element method. The influence of additional cutout shape and height to the stress distribution around the additional cutout were investigated and analyzed. Meanwhile, the static and fatigue test on this structure details was carried out. The stress distribution was consistent with the finite element analysis results. The fatigue property for additional cutout height of 95mm was slightly better than that of 61.5 mm.

A Study on Changes of Mechanical Properties and Microstructure in Porcelain Fused to Gold Alloys by Heat Treatment (도재소부용 금합금의 열처리에 따른 기계적 성질 및 미세조직 변화에 관한 연구)

  • Nam, Sang-Yong;Kwak, Dong-Ju;Cha, Sung-Soo
    • Journal of Technologic Dentistry
    • /
    • v.31 no.4
    • /
    • pp.9-15
    • /
    • 2009
  • The purpose of this study was to observe the change of mechanical property and microstructure in porcelain fused to gold alloy by heat treatment. PFG alloys are composed with Au-Pd-Ag alloy of the additional elements with indium, tin and copper. Specimens were tested in hardness using vicker,s micro-hardness tester and the surface micro structural changes were analysed by SEM and EDS. The results were as fellows: 1. The vickers hardness showed highest in Au-Pd-Ag alloy of the additional element with tin. 2. By hardening-oxiding result, the vicker,s hardness increased in additional element with tin but there was no significant difference in additional elements with indium and copper. 3. The surface oxide layer of Au-Pd-Ag alloy with added indium and tin increased but there was small change in additional element with copper. 4. The elements of indium and tin increased with increasing heat treatment in the surface alloy.

  • PDF

Dynamic behaviour of stiffened and damaged coupled shear walls

  • Meftah, S.A.;Tounsi, A.;Adda-Bedia, E.A.
    • Computers and Concrete
    • /
    • v.3 no.5
    • /
    • pp.285-299
    • /
    • 2006
  • The free vibration of stiffened and damaged coupled shear walls is investigated using the mixed finite element method. The anisotropic damage model is adopted to describe the damage extent of the reinforced concrete shear wall element. The internal energy of a locally damaged shear wall element is derived. Polynomial shape functions established by Kwan are used to present the component of displacements vector on each point within the wall element. The principle of virtual work is employed to deduce the stiffness matrix of a damaged shear wall element. The stiffened system is reinforced by an additional stiffening beam at some level of the structure. This induces additional axial forces, and thus reduces the bending moments in the walls and the lateral deflection, and increases the natural frequencies. The effects of the damage extent and the stiffening beam on the free vibration characteristics of the structure are studied. The optimal location of the stiffening beam for increasing as far as possible the first natural frequency of vibration is presented.

Improvements to the analysis of floorbeams with additional web cutouts for orthotropic plated decks with closed continuous ribs

  • De Corte, Wouter;Van Bogaert, Philippe
    • Steel and Composite Structures
    • /
    • v.7 no.1
    • /
    • pp.1-18
    • /
    • 2007
  • Additional cutouts in the floorbeam webs of orthotropic plated bridge decks relieve the highly stressed lower flange of the ribs passing through these floorbeam webs from possible fatigue damage. Conversely, the floorbeam webs themselves suffer from high stress concentrations, especially along the free edges of the additional cutouts. These stresses result from a combination of direct introduction of vertical traffic loads in the weakened web and from the truss action of the floorbeam. The latter differs from a simple beam action due to the presence of the openings and corresponds more to the behaviour of a Vierendeel truss. Close assessment of the appearing stresses, highly relevant for fatigue resistance, requires the use of elaborate finite element modelling. However, a full finite element analysis merely provides the results of total stresses, leaving the researcher or designer the difficult task of finding the origin of these stress components. This paper presents a calculation method for cutout stresses based on a combination of a framework analysis and a two dimensional finite element analysis of much smaller parts of the floorbeam. This method provides more insight in the origin of the stress components, as well as it simplifies any comparison of different additional cutout geometries, independent of the floorbeam topology.

The Effect of Additional Elements X on Magnetic Properties of CoCrTa/Cr-X Thin Film (CoCrTa/Cr-X 자성박막의 자기적성질에 미치는 첨가원소 X의 영향)

  • 김준학;박정용;남인탁;홍양기
    • Journal of the Korean Magnetics Society
    • /
    • v.3 no.4
    • /
    • pp.314-319
    • /
    • 1993
  • The Effects of additional element X (X = Si, Mo, Cu, Gd) on magnetic properties and microstructure of Co-1Zat%Cr-Zat%Ta/Cr-X magnetic thin film were investigated. The thickness changes of Cr-X underlayer and CoCrTa magnetic layer were in the range of $1000~2000\AA$ and $200~800\AA$. respectively. Substrate temperatures were controlled from $100^{\circ}C$ to $200^{\circ}C$. Increase of coercivity by about 100~200 Oe was observed in CoCrTa/Cr-X thin films compared to those without additional X element. Cu was the most effective additional element for increasing coercivity. CoCrTa/Cr-Cu thin film shows relatively high coercivity in $1500\AA$ underlayer thickness and $600\AA$ magnetic layer thickness.

  • PDF

Effects of Pre-tension and Additional Half-pin on Fracture Stability in Hybrid External Fixator System (강선의 인장력과 추가 Half pin이 혼성외고정장치 시스템의 안정성에 미치는 영향)

  • 김윤혁;이현근;박원만;오종건
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2004.10a
    • /
    • pp.389-392
    • /
    • 2004
  • It is clinically well known that pre-tension of wires increases the fracture stability in ring or hybrid external fixation. In some cases, additional half pin should be necessary to increase the stability when soft tissue impalement occurs during fixation. In this paper, the fracture stability of a hybrid external fixator system with different pre-tension effects and additional half-pins was analysed using FEM to investigate the effects of these pre-tension and half pin on the system stability quantitatively. 3-D finite element models of five different fixator frames were developed using by beam elements. In axial compression analysis, the fracture stiffness was increased maximally 62% as the pre-tension increased. In torsion analysis, in the other hand, there is little variations in the fracture stiffness. Additional half pin increased the system stiffness about 200 %. From the results, proper pre-tension and additional half pin would provide good methods to increase the fracture stability of the hybrid external fixator and provide more surgical options to minimize soft tissue damage at the fracture site.

  • PDF

Spline-Based Finite Element Analysis with T-Spline Local Refinement (T-스플라인 국부세분화를 고려한 스플라인 기반 유한요소해석)

  • Seo, Yu-Deok;Kim, Ki-Seung;Youn, Sung-Kie
    • Proceedings of the KSME Conference
    • /
    • 2007.05a
    • /
    • pp.366-371
    • /
    • 2007
  • In many CAD systems, NURBS has been employed to construct exact geometries. Recently, NURBS finite element analysis methods were proposed by some authors for convenient connection between CAD and finite element analysis. Additional advantages of NURBS FEA, such as exact geometry and no mesh generation, are obtained. However, NURBS is inefficient in local refinement and merging patches. For refinement of local region in interest, additional control points should be inserted into the entire row or column which contains the local region. There is another inefficiency of NURBS during merging patches into a large structure due to propagation of control points. In order to overcome these inefficiencies of NURBS, T-spline was proposed by Sederberg. In this work, T-spline based finite element method is proposed for efficient local refinement and merging patches. At first, accuracy and efficiency of NURBS FEA is verified and efficiency of T-spline FEA is verified by comparing with NURBS FEA.

  • PDF

Feasibility Study on Similarity Principle in Discrete Element Analysis (이산요소법을 이용한 수치해석에서의 상사성 이론의 적용성 검토)

  • Yun, Taeyoung;Park, Hee Mun
    • International Journal of Highway Engineering
    • /
    • v.18 no.2
    • /
    • pp.51-60
    • /
    • 2016
  • PURPOSES : The applicability of the mechanics-based similarity concept (suggested by Feng et al.) for determining scaled variables, including length and load, via laboratory-scale tests and discrete element analysis, was evaluated. METHODS: Several studies on the similarity concept were reviewed. The exact scaling approach, a similarity concept described by Feng, was applied in order to determine an analytical solution of a free-falling ball. This solution can be considered one of the simplest conditions for discrete element analysis. RESULTS : The results revealed that 1) the exact scaling approach can be used to determine the scale of variables in laboratory tests and numerical analysis, 2) applying only a scale factor, via the exact scaling approach, is inadequate for the error-free replacement of small particles by large ones during discrete element analysis, 3) the level of continuity of flowable materials such as SCC and cement mortar seems to be an important criterion for evaluating the applicability of the similarity concept, and 4) additional conditions, such as the kinetics of particle, contact model, and geometry, must be taken into consideration to achieve the maximum radius of replacement particles during discrete element analysis. CONCLUSIONS : The concept of similarity is a convenient tool to evaluate the correspondence of scaled laboratory test or numerical analysis to physical condition. However, to achieve excellent correspondence, additional factors, such as the kinetics of particles, contact model, and geometry, must be taken into consideration.

Proposal of residual stress mitigation in nuclear safety-related austenitic stainless steel TP304 pipe bended by local induction heating process via elastic-plastic finite element analysis

  • Kim, Jong-Sung;Kim, Kyoung-Soo;Oh, Young-Jin;Oh, Chang-Young
    • Nuclear Engineering and Technology
    • /
    • v.51 no.5
    • /
    • pp.1451-1469
    • /
    • 2019
  • This paper proposes a residual stress mitigation of a nuclear safety-related austenitic stainless steel TP304 pipe bended by local induction heating process via performing elastic-plastic finite element analysis. Residual stress distributions of the pipe bend were calculated by performing finite element analysis. Validity of the finite element analysis procedure was verified via comparing with temperature histories measured by using thermocouples, ultrasonic thickness measurement results, and residual stress measurement results by a hole-drilling method. Parametric finite element stress analysis was performed to investigate effects of the process and geometric shape variables on the residual stresses on inner surfaces of the pipe by applying the verified procedure. As a result of the parametric analysis, it was found that it is difficult to considerably reduce the inner surface residual stresses by changing the existing process and geometric shape variables. So, in order to mitigate the residual stresses, effect of an additional process such as cooling after the bending on the residual stresses was investigated. Finally, it was identified that the additional heating after the bending can significantly reduce the residual stresses while other variables have insignificant effect.