• 제목/요약/키워드: Cohesive element

검색결과 147건 처리시간 0.027초

Linking bilinear traction law parameters to cohesive zone length for laminated composites and bonded joints

  • Li, Gang;Li, Chun
    • Advances in aircraft and spacecraft science
    • /
    • 제1권2호
    • /
    • pp.177-196
    • /
    • 2014
  • A theoretical exploration for determining the characteristic length of the cohesive zone for a double cantilever beam (DCB) specimen under mode I loading was conducted. Two traction-separation laws were studied: (i) a law with only a linear elastic stage from zero to full traction strength; and (ii) a bilinear traction law illustrating a progressive softening stage. Two analytical solutions were derived for the first law, which fit well into two existing solution groups. A transcendental equation was derived for the bilinear traction law, and a graphical method was presented to identify the resultant cohesive zone length. The study using the bilinear traction law enabled the theoretical investigation of the individual effects of cohesive law parameters (i.e., strength, stiffness, and fracture energy) on the cohesive zone length. Correlations between the theoretical and finite element (FE) results were assessed. Effects of traction law parameters on the cohesive zone length were discussed.

점성토에서 유한요소해석에 의한 무소음.무진동 스크류PHC말뚝의 거동 분석 (An Analysis on the Behaviors of a Noise & Vibration-Free Screw PHC Pile in cohesive Soils by Finite Element Code)

  • 김영필;하영민;정호영;황정환;최용규
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
    • /
    • pp.377-384
    • /
    • 2009
  • Noise & vibration-free screw pile method is being developed for solution of noise and vibration problem in existing pile method. In this paper, prior to pilot test construction, conditions which a PHC pile and a screw PHC pile were constructed into ground were modeled by finite element code and through the parametric study in cohesive soils, the behaviors of two kinds of pile according to soil characteristics were compared.

  • PDF

응집 영역 요소를 이용한 고분자 접착 테이프의 박리거동 모사 (Numerical Simulation of the Delamination Behavior of Polymeric Adhesive Tapes Using Cohesive Zone Element)

  • 장진혁;성민창;유웅열
    • Composites Research
    • /
    • 제29권4호
    • /
    • pp.203-208
    • /
    • 2016
  • 금속/고분자 샌드위치 복합재는 경량성과 제진, 방음 등의 다기능성의 측면에서 기존의 스틸 강판을 대체할 후보 중 하나로서 연구되고 있다. 금속/고분자 복합재의 활용하기 위해서는 접착력을 바탕으로 한 박리 거동 예측이 매우 중요한 요소이다. 본 연구에서는 응집요소를 사용하여 유한요소 해석을 통해 접착제를 사용한 고분자 테이프의 박리거동 해석을 수행하였다. 응집요소의 특성은 박리시험과 역학 관계로부터 도출한 파괴인성을 통해 정의하였고 이를 해석에 적용하였다. 스틸 강판에서 고분자 테이프를 박리하는 시험을 모사하였고, 해석결과와 시험결과를 비교하여 박리 거동 모사가 가능함을 확인하였다.

응집영역모델을 이용한 정수압 성형 해석시 고무몰드의 변형거동 (Deformation of the Rubber Mold by Using the Cohesive Zone Model Under Cold Isostatic Pressing)

  • 이성철;김기태
    • 대한기계학회논문집A
    • /
    • 제32권5호
    • /
    • pp.387-395
    • /
    • 2008
  • Stress distribution and interfacial debonding process at the interface between a rubber mold and a powder compact were analyzed during unloading under cold isostatic pressing. The Cap model proposed by Lee and Kim was used for densification behavior of powder based on the parameters involved in the yield function of general Cap model and volumetric strain evolution. Cohesive elements incorporating a bilinear cohesive zone model were also used to simulate interfacial debonding process. The Cap model and the cohesive zone model were implemented into a finite element program (ABAQUS). Densification behavior of powder was investigated under various interface conditions between a rubber mold and a powder compact during loading. The residual tensile stress at the interface was investigated for rubber molds with various elastic moduli under perfect bonding condition. The variations of the elastic energy density of a rubber mold and the maximum principal stress of a powder compact were calculated for several interfacial strengths at the interface during unloading.

A new geomechanical approach to investigate the role of in-situ stresses and pore pressure on hydraulic fracture pressure profile in vertical and horizontal oil wells

  • Saberhosseini, Seyed Erfan;Keshavarzi, Reza;Ahangari, Kaveh
    • Geomechanics and Engineering
    • /
    • 제7권3호
    • /
    • pp.233-246
    • /
    • 2014
  • Estimation of fracture initiation pressure is one of the most difficult technical challenges in hydraulic fracturing treatment of vertical or horizontal oil wells. In this study, the influence of in-situ stresses and pore pressure values on fracture initiation pressure and its profile in vertical and horizontal oil wells in a normal stress regime have been investigated. Cohesive elements with traction-separation law (XFEM-based cohesive law) are used for simulating the fracturing process in a fluid-solid coupling finite element model. The maximum nominal stress criterion is selected for initiation of damage in the cohesive elements. The stress intensity factors are verified for both XFEM-based cohesive law and analytical solution to show the validation of the cohesive law in fracture modeling where the compared results are in a very good agreement with less than 1% error. The results showed that, generally by increasing the difference between the maximum and minimum horizontal stress, the fracture pressure and its profile has been strongly changed in the vertical wells. Also, it's been clearly observed that in a horizontal well drilled in the direction of minimum horizontal stress, the values of fracture pressure have been significantly affected by the difference between overburden pressure and maximum horizontal stress. Additionally, increasing pore pressure from under-pressure regime to over-pressure state has made a considerable fall on fracture pressure in both vertical and horizontal oil wells.

A boundary element approach for quasibrittle fracture propagation analysis

  • Tin-Loi, F.
    • Structural Engineering and Mechanics
    • /
    • 제8권5호
    • /
    • pp.439-452
    • /
    • 1999
  • A simple numerical scheme suitable for tracing the fracture propagation path for structures idealized by means of Hillerborg's classical cohesive crack model is presented. A direct collocation, multidomain boundary element method is adopted for the required space discretization. The algorithm proposed is necessarily iterative in nature since the crack itinerary is a priori unknown. The fracture process is assumed to be governed by a path-dependent generally nonlinear softening law. The potentialities of the method are illustrated through two examples.

2-D meso-scale complex fracture modeling of concrete with embedded cohesive elements

  • Shen, Mingyan;Shi, Zheng;Zhao, Chao;Zhong, Xingu;Liu, Bo;Shu, Xiaojuan
    • Computers and Concrete
    • /
    • 제24권3호
    • /
    • pp.207-222
    • /
    • 2019
  • This paper has presented an effective and accurate meso-scale finite element model for simulating the fracture process of concrete under compression-shear loading. In the proposed model, concrete is parted into four important phases: aggregates, cement matrix, interfacial transition zone (ITZ), and the initial defects. Aggregate particles were modelled as randomly distributed polygons with a varying size according to the sieve curve developed by Fuller and Thompson. With regard to initial defects, only voids are considered. Cohesive elements with zero thickness are inserted into the initial mesh of cement matrix and along the interface between aggregate and cement matrix to simulate the cracking process of concrete. The constitutive model provided by ABAQUS is modified based on Wang's experiment and used to describe the failure behaviour of cohesive elements. User defined programs for aggregate delivery, cohesive element insertion and modified facture constitutive model are developed based on Python language, and embedded into the commercial FEM package ABAQUS. The effectiveness and accuracy of the proposed model are firstly identified by comparing the numerical results with the experimental ones, and then it is used to investigate the effect of meso-structure on the macro behavior of concrete. The shear strength of concrete under different pressures is also involved in this study, which could provide a reference for the macroscopic simulation of concrete component under shear force.

목포해역 점착성 퇴적물의 수송에 관한 수치모의 (Numerical Modeling of Cohesive Sediment Transport at Mokpo Coastal Zone)

  • 정태성;김태식;정동국
    • 한국해양환경ㆍ에너지학회지
    • /
    • 제9권1호
    • /
    • pp.36-44
    • /
    • 2006
  • 연안해역에서 점착성 퇴적물의 수송과정을 수치모의하였다. 복잡한 지형을 가진 연안해역에 효과적인 유한요소모형 이 해수유동과 퇴적물 수송을 모의하기 위해 수립되었다. 침식률을 기존 연구결과 및 바닥퇴적물 시료의 물리특성 분석자료를 가지고 편리하게 결정하였으며, 모의결과는 관측된 부유사 농도의 시간변화와 잘 일치하는 양호한 계산 결과를 보였다, 따라서 본 연구에서 사용한 침식률 결정방법이 퇴적물 수송모의에 효과적으로 활용될 수 있음을 확인할 수 있었다.

  • PDF

유한요소법에 의한 피로균열 진전 시뮬레이션 (Simulation of Fatigue Crack Propagation by Finite Element Analysis)

  • 구병춘;양승용;박준서
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2005년도 춘계학술대회 논문집
    • /
    • pp.337-340
    • /
    • 2005
  • The effect of residual stress on fatigue crack growth was investigated in terms of finite element analysis. Simulations were performed on a CT specimen in plane strain. An interface-cohesive element that accounts for damage accumulation due to fatigue along the notch direction has been used. Numerical results show that fatigue crack growth rate slows down when compressive residual stress field exists in front of the crack tip.

  • PDF

고체추진로켓 내부에서 발생하는 동적 파괴 현상과 유체-고체 상호작용의 시뮬레이션 - Part 1 (이론적 측면) (Simulation of dynamic fracture and fluid-structure interaction in solid propellant rockets : Part 1 (theoretical aspects))

  • 황찬규
    • 한국산학기술학회논문지
    • /
    • 제9권2호
    • /
    • pp.286-290
    • /
    • 2008
  • 본 논문은 고체 추진 로켓의 연소 중에 발생하는 고체추진체의 동적 파괴 현상 및 유체-구조 상호작용을 시뮬레이션 하기 위한 프로그램 개발에 대한 것이다. 개발된 프로그램은 구조해석을 위한 CVFE (cohesive Volumetric Finite Element) 방법과 외재적 ALE (Arbitrary Lagrangian Eulerian) 방법을 응용한 유한요소법 코드와 유동해석을 위한 외재적 비정렬 유한 체적 오일러 코드(Explicit Unstructured Finite Volume Euler code)로 구성된다. 개발된 프로그램의 또 다른 중요한 특징은 균열의 전파와 고체추진체의 변형에 따라 생기는 추진제 형상의 대변형이 발생할 때, 새로 생긴 유체 영역에서의 격자의 확장과 복구되는 능력이다.