• 제목/요약/키워드: simulation, fracture mechanics

검색결과 123건 처리시간 0.027초

Numerical simulation of the femur fracture under static loading

  • El Sallah, Zagane Mohammed;Smail, Benbarek;Abderahmane, Sahli;Bouiadjra, B. Bachir;Boualem, Serier
    • Structural Engineering and Mechanics
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    • 제60권3호
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    • pp.405-412
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    • 2016
  • Bone is a living material with a complex hierarchical structure that gives it remarkable mechanical properties. Bone constantly undergoes mechanical. Its quality and resistance to fracture is constantly changing over time through the process of bone remodeling. Numerical modeling allows the study of the bone mechanical behavior and the prediction of different trauma caused by accidents without expose humans to real tests. The aim of this work is the modeling of the femur fracture under static solicitation to create a numerical model to simulate this element fracture. This modeling will contribute to improve the design of the indoor environment to be better safe for the passengers' transportation means. Results show that vertical loading leads to the femur neck fracture and horizontal loading leads to the fracture of the femur diaphysis. The isotropic consideration of the bone leads to bone fracture by crack propagation but the orthotropic consideration leads to the fragmentation of the bone.

ON THE TREATMENT OF DUCTILE FRACTURE BY THE LOCAL APPROACH CONCEPT IN CONTINUUM DAMAGE MECHANICS : THEORY AND EXAMPLE

  • Kim, Seoung-Jo;Kim, Jin-Hee;Kim, Wie-Dae
    • Journal of Theoretical and Applied Mechanics
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    • 제2권1호
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    • pp.31-50
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    • 1996
  • In this paper, a finite element analysis based on the local approach concept to fracture in the continuum damage mechanics is performed to analyze ductile fracture in two dimensional quasi-static state. First an isotropic damage model based on the generalized concept of effective stress is proposed for structural materials in the context of large deformation. In this model, the stiffness degradation is taken as a measure of damage and so, the fracture phenomenon can be explained as the critical deterioration of stiffness at a material point. The modified Riks' continuation technique is used to solve incremental iterative equations. Crack propagation is achieved by removing critically damaged elements. The mesh size sensitivity analysis and the simulation of the well known shearing mode failure in plane strain state are carried out to verify the present formulation. As numerical examples, an edge cracked plate and the specimen with a circular hole under plane stress are taken. Load-displacement curves and successively fractured shapes are shown. From the results, it can be concluded that the proposed model based on the local approach concept in the continuum damage mechanics may be stated as a reasonable tool to explain ductile fracture initiation and crack propagation.

확률론적 파괴역학 수법의 적용성 검토 (Application of Probabilistic Fracture Mechanics Methodology)

  • 이준성;곽상록;김영진
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2001년도 춘계학술대회 논문집
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    • pp.667-670
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    • 2001
  • For major structural components periodic inspections and integrity assessments are needed for the safety. However, many flaws are undetectable because sampling inspection is carried out during in-service inspection. Probabilistic integrity assessment is applied to take into consideration of uncertainty and variance of input parameters arise due to material properties and undetectable cracks. This paper describes a Probabilistic Fracture Mechanics(PEM) analysis based on the Monte Carlo(MC) algorithms. Taking a number of sampling data of probabilistic variables such as fracture toughness value, crack depth and aspect ratio of an initial surface crack, a MC simulation of failure judgement of samples is performed. For the verification of this analysis, a comparison study of th PFM analysis using a commercial code, mathematical method is carried out and a good agreement was observed between those results.

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A mesoscale stress model for irradiated U-10Mo monolithic fuels based on evolution of volume fraction/radius/internal pressure of bubbles

  • Jian, Xiaobin;Kong, Xiangzhe;Ding, Shurong
    • Nuclear Engineering and Technology
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    • 제51권6호
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    • pp.1575-1588
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    • 2019
  • Fracture near the U-10Mo/cladding material interface impacts fuel service life. In this work, a mesoscale stress model is developed with the fuel foil considered as a porous medium having gas bubbles and bearing bubble pressure and surface tension. The models for the evolution of bubble volume fraction, size and internal pressure are also obtained. For a U-10Mo/Al monolithic fuel plate under location-dependent irradiation, the finite element simulation of the thermo-mechanical coupling behavior is implemented to obtain the bubble distribution and evolution behavior together with their effects on the mesoscale stresses. The numerical simulation results indicate that higher macroscale tensile stresses appear close to the locations with the maximum increments of fuel foil thickness, which is intensively related to irradiation creep deformations. The maximum mesoscale tensile stress is more than 2 times of the macroscale one on the irradiation time of 98 days, which results from the contributions of considerable volume fraction and internal pressure of bubbles. This study lays a foundation for the fracture mechanism analysis and development of a fracture criterion for U-10Mo monolithic fuels.

High-Yield Etching-Free Transfer of Graphene: A Fracture Mechanics Approach

  • Yoon, Taeshik;Jo, Woo Sung;Kim, Taek-Soo
    • 마이크로전자및패키징학회지
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    • 제21권2호
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    • pp.59-64
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    • 2014
  • Transfer is the critical issue of producing high-quality and scalable graphene electronic devices. However, conventional transfer processes require the removal of an underlying metal layer by wet etching process, which induces significant economic and environmental problems. We propose the etching-free mechanical releasing of graphene using polymer adhesives. A fracture mechanics approach was introduced to understand the releasing mechanism and ensure highyield process. It is shown that the thickness of adhesive and target substrate affect the transferability of graphene. Based on experimental and fracture mechanics simulation results, we further observed that compliant adhesives can reduce the adhesive stress during the transfer, which also enhances the success probability of graphene transfer.

Hydraulic fracture simulation of concrete using the SBFEM-FVM model

  • Zhang, Peng;Du, Chengbin;Zhao, Wenhu;Zhang, Deheng
    • Structural Engineering and Mechanics
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    • 제80권5호
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    • pp.553-562
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    • 2021
  • In this paper, a hybrid scaled boundary finite element and finite volume method (SBFEM-FVM) is proposed for simulating hydraulic-fracture propagation in brittle concrete materials. As a semi-analytical method, the scaled boundary finite element method is introduced for modelling concrete crack propagation under both an external force and water pressure. The finite volume method is employed to model the water within the crack and consider the relationship between the water pressure and the crack opening distance. The cohesive crack model is used to analyse the non-linear fracture process zone. The numerical results are compared with experimental data, indicating that the F-CMOD curves and water pressure changes under different loading conditions are approximately the same. Different types of water pressure distributions are also studied with the proposed coupled model, and the results show that the internal water pressure distribution has an important influence on crack propagation.

소규모 냉각재 상실사고하의 원자로 압력용기에 대한 확률론적 파괴역학 평가 (Evaluation of Probabilistic Fracture Mechanics for Reactor Pressure Vessel under SBLOCA)

  • 김종욱;이규만;김태완
    • 한국압력기기공학회 논문집
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    • 제4권2호
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    • pp.13-19
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    • 2008
  • In order to predict a remaining life of a plant, it is necessary to select the components that are critical to the plant life. The remaining life of those components shall be evaluated by considering the aging effect of materials used as well as numerous factors. However, when evaluating reliability of nuclear structural components, some problems are quite formidable because of lack of information such as operating history, material property change and uncertainty in damage models. Accordingly, if structural integrity and safety are evaluated by the deterministic fracture mechanics approach, it is expected that the results obtained are too conservative to perform a rational evaluation of plant life. The probabilistic fracture mechanics approaches are regarded as appropriate methods to rationally evaluate the plant life since they can consider various uncertainties such as sizes and shapes of cracks and degradation of material strength due to the aging effects. The objective of this study is to evaluate the structural integrity for a reactor pressure vessel under the small break loss of coolant accident by applying the deterministic and probabilistic fracture mechanics. The deterministic fracture mechanics analysis was performed using the three dimensional finite element model. The probabilistic integrity analysis was based on the Monte Carlo simulation. The selected random variables are the neutron fluence on the vessel inside surface, the content of copper, nickel, and phosphorus in the reactor pressure vessel material, and initial RTNDT.

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몬테카를로 시뮬레이션을 이용한 확률론적 파괴역학 수법의 적용성 검토 (Application of Probabilistic Fracture Mechanics Technique Using Monte Carlo Simulation)

  • 이준성;곽상록;김영진
    • 한국정밀공학회지
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    • 제18권10호
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    • pp.154-160
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    • 2001
  • For major structural components periodic inspections and integrity assessments are needed for the safety. However, many flaws are undetectable because sampling inspection is carried out during in-service inspection. Probabilistic integrity assessment is applied to take into consideration of uncertainty and variance of input parameters arise due to material properties and undetectable cracks. This paper describes a Probabilistic Fracture Mechanics(PFM) analysis based on the Monte Carlo(MC) algorithms. Taking a number of sampling data of probabilistic variables such as fracture toughness value, crack depth and aspect ratio of an initial surface crack, a MC simulation of failure judgement of samples is performed. for the verification of this analysis, a comparison study of the PFM analysis using a commercial code, mathematical method is carried out and a good agreement was observed between those results.

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확률론적 파괴역학을 도입한 CANDU 압력관의 예리한 결함에 대한 건전성평가 (Integrity Assessment of Sharp Flaw in CANDU Pressure Tube Using Probabilistic Fracture Mechanics)

  • 이준성;곽상록;김영진;박윤원
    • 대한기계학회논문집A
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    • 제26권4호
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    • pp.653-659
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    • 2002
  • This paper describes a probabilistic fracture mechanics(PFM) analysis based on Monte Carlo(MC) simulation. In the analysis of CANDU pressure tube, the depth and aspect ratio of an initial semi-elliptical surface crack, a fracture toughness value and delayed hydride cracking(DHC) velocity are assumed to be probabilistic variables. As an example, some failure probabilities of piping and CANDU pressure tube are calculated using MC method with the stratified sampling MC technique, taking analysis conditions of normal operations. In the stratified MC simulation, a sampling space of probabilistic variables is divided into a number of small cells. For the verification of analysis results, a comparison study of the PFM analysis using other commercial code is carried out and a good agreement was observed between those results.

Sensitivity analysis of skull fracture

  • Vicini, Anthony;Goswami, Tarun
    • Biomaterials and Biomechanics in Bioengineering
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    • 제3권1호
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    • pp.47-57
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    • 2016
  • Results from multiple high profile experiments on the parameters influencing the impacts that cause skull fractures to the frontal, temporal, and parietal bones were gathered and analyzed. The location of the impact as a binary function of frontal or lateral strike, the velocity, the striking area of the impactor, and the force needed to cause skull fracture in each experiment were subjected to statistical analysis using the JMP statistical software pack. A novel neural network model predicting skull fracture threshold was developed with a high statistical correlation ($R^2=0.978$) and presented in this text. Despite variation within individual studies, the equation herein proposes a 3 kN greater resistance to fracture for the frontal bone when compared to the temporoparietal bones. Additionally, impacts with low velocities (<4.1 m/s) were more prone to cause fracture in the lateral regions of the skull when compared to similar velocity frontal impacts. Conversely, higher velocity impacts (>4.1 m/s) showed a greater frontal sensitivity.