• 제목/요약/키워드: fracture/fracture criteria

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접착영역모델을 이용한 클린칭 접합부의 해석 모델 설계 및 적용 (Analysis and Application of Mechanical Clinched Joint Using Cohesive Zone Model)

  • 황빛나;이찬주;이선봉;김병민
    • 소성∙가공
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    • 제19권4호
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    • pp.217-223
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    • 2010
  • The objective of this study is to propose the FE model for mechanical clinched joint using cohesive zone model to analyze its failure behavior under impact loading. Cohesive zone model (CZM) is two-parameter failure criteria approach, which could describe the failure behavior of joint using critical stress and fracture toughness. In this study, the relationship between failure behavior of mechanical clinched joint and fracture parameters is investigated by FE analysis with CZM. Using this relationship, the critical stress and fracture toughness for tensile and shear mode are determined by H-type tensile test and lap shear test, which were made of 5052 aluminum alloy. The fracture parameters were applied to the tophat impact test to evaluate the crashworthiness. Compared penetration depth and energy absorption at the point where 50% of total displacement in result of FE analysis and experiment test for impact test, those has shown similar crashworthiness.

FATIGUE LIFE PREDICTION OF RUBBER MATERIALS USING TEARING ENERGY

  • Kim, H.;Kim, H.Y.
    • International Journal of Automotive Technology
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    • 제7권6호
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    • pp.741-747
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    • 2006
  • It has been almost impossible to predict the fatigue life in the field of rubber materials by numerical methods. One of the reasons is that there are no obvious fracture criteria and excessively various ways of mixing processes. Tearing energy is considered as a fracture criterion which can be applied to rubber compounds regardless of different types of fillers, relative to other fracture factors. Fatigue life of rubber materials can be approximately predicted based on the assumption that the latent defect caused by contaminants or voids in the matrix, imperfectly dispersed compounding ingredients, mold lubricants and surface flaws always exists. Numerical expression for the prediction of fatigue life was derived from the rate of rough cut growth region and the formulated tearing energy equation. Endurance test data for dumbbell specimens were compared with the predicted fatigue life for verification. Also, fatigue life of industrial rubber components was predicted.

원자력 발전소 배관에 대한 파단전누설 개념 적용기준의 수정 (Modification of Current Leak Before Break Criteria for Nuclear Piping System)

  • 유영준;김영진
    • 대한기계학회논문집A
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    • 제20권6호
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    • pp.1862-1871
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    • 1996
  • The puopose of this paper is sto modify the current LBB criteria. The validity of current LBB criteria and current standard LBB analysis mehtod are evaluated using linear elastic fracture mechanics and elastic-plastic fracture mechanics. The results of evaluation demonstrate that the current LBB driteria are very conservative and some level of margins already exist in the standard LBB analysis method. Thus, the margin on load .root. and margin on crack size 2 can be eliminated to extend LBB application for the samller diameter pipe.

자동차용 극저탄소 냉연강판의 Mash Sem TB를 이용한 용접시 특성에 관한 연구 (A study on characteristics of Mash Seam TB weld in ultra-low carbon steel applied on automotive body)

  • Han, Chang-Woo;Lee, Chang-Hee
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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    • pp.189-191
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    • 2001
  • This study introduces the new way for the evaluation criteria of the Mash-Seam Tailored Blank weldability, The materials used are low carbon automotive galvanized and high strength steels and the evaluation of weldability are examined with various thickness. Welding tests were conducted for both similar thickness and dissimilar thickness cases. The criteria developed for optimum welding conditions were based on the relationship among results of die press forming test, weld transverse tensile test, Erichsen test and microhardness measurements. The application of the developed criteria(fracture ratio, strength ratio, etc) in obtaining optimum welding condition revealed that a weld which satisfied ant of the criteria did not fracture during actual die press test.

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극저탄소 냉연강판의 Mash Seam TB를 이용한 용접 시 특성과 평가에 관한 연구 (A study on characteristics and evaluation of Mash Seam TB weld in ultra-low carbon steel applied on automotive body)

  • Han, Chang-Woo;Lee, Chang-Hee
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2001년도 추계학술발표대회 개요집
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    • pp.81-84
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    • 2001
  • This study introduces the new way for the evaluation criteria of the Mash-Seam Tailored Blank weldability, The materials used are low carbon automotive galvanized and high strength steels and the evaluation of weldability are examined with various thickness. Welding tests were conducted for both similar thickness and dissimilar thickness cases. The criteria developed for optimum welding conditions were based on the relationship among results of die press forming test, forming limit diagram, Erichsen test and microhardness measurements. The application of the developed criteria(fracture ratio, strength ratio, etc) in obtaining optimum welding condition revealed that a weld which satisfied ant of the criteria did not fracture during actual die press test and FLD dome test.

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경첩 운동이 가능한 외고정장치를 이용한 Pilon골절의 치료 (Treatment of Pilon Fracture using Articulated External Fixator with Hinge)

  • 박인헌;이기병;송경원;이진영;이승용
    • 대한족부족관절학회지
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    • 제1권1호
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    • pp.30-37
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    • 1997
  • Pilon fracture is an intraarticular fracture of distal tibia. It is high energy injury with significantly associated soft tissue damage, bone comminution, and articular surface disruption. Until recently, this treatment has followed the AO principles, Because the risk of complications outweighs potential benefits, the principle of a Pilon fracture treatment are changing. Newer techniques using articulated external fixation minimize disturbance of the soft tissue envelope and have decreased these complications. Series of 5 patients with Pilon fracture were treated by articulated external fixator and followed up more than 12 monthes at the Department of orthopaedic surgery, Kang Dong Sacred Heart Hospital, College of medicine, Hallym University. The results were as follows: 1. The type of fracture were type C2(3 cases),type C3(2 cases) according to AO-$M{\ddot{u}}ller$ classification. 2. The clinical results according to functional criteria by Mast and Teipner were good in 4 cases and poor in 1 case, which is an old fracture. 3. Techniques utilizing articulated external fixator were associated with satisfactory results and appeared to significantly decrease the incidence of soft tissue complication, post-traumatic arthritis, osteoporosis, and fibrosis of ankle joint.

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Compression Strength Size Effect on Carbon-PEEK Fiber Composite Failing by Kink Band Propagation

  • Kim, Jang-Ho
    • KCI Concrete Journal
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    • 제12권1호
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    • pp.57-68
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    • 2000
  • The effect of structure size on the nominal strength of unidirectional fiber-polymer composites, failing by propagation of a kink band with fiber microbuckling, is analyzed experimentally and theoretically. Tests of novel geometrically similar carbon-PEEK specimens, with notches slanted so as to lead to a pure kink band (without shear or splitting cracks), are conducted. The specimens are rectangular strips of widths 15.875, 31.75. and 63.5 mm (0.625, 1.25 and 2.5 in and gage lengths 39.7, 79.375 and 158.75 mm (1.563, 3.125 and 6.25 in.). They reveal the existence of a strong (deterministic. non-statistical) size effect. The doubly logarithmic plot of the nominal strength (load divided by size and thickness) versus the characteristic size agrees with the approximate size effect law proposed for quasibrittle failures in 1983 by Bazant This law represents a gradual transition from a horizontal asymptote, representing the case of no size effect (characteristic of plasticity or strength criteria), to an asymptote of slope -1/2 (characteristic of linear elastic fracture mechanics. LEFM) . The size effect law for notched specimens permits easy identification of the fracture energy of the kink bandand the length of the fracture process zone at the front of the band solely from the measurements of maximum loads. Optimum fits of the test results by the size effect law are obtained, and the size effect law parameters are then used to identify the material fracture characteristics, Particularly the fracture energy and the effective length of the fracture process zone. The results suggest that composite size effect must be considered in strengthening existing concrete structural members such as bridge columns and beams using a composite retrofitting technique.

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지하저장공동 주변 불연속 암반에서의 가스-물 천이유동해석을 위한 개별균열 유동모델의 개발 및 응용 (Development and Its Application of a Discrete Fracture Flow Model for the Analysis of Gas-Water Transient Flow in Fractured Rock Masses Around Storage Cavern)

  • 나승훈;성원모
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2000년도 가을 학술발표회 논문집
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    • pp.705-712
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    • 2000
  • The fluid generally flows through fractures in crystalline rocks where most of underground storage facilities are constructed because of their low hydraulic conductivities. The fractured rock is better to be conceptualized with a discrete fracture concept, rather continuum approach. In the aspect of fluid flow in underground, the simultaneous flow of groundwater and gas should be considered in the cases of generation and leakage of gas in nuclear waste disposal facilities, air sparging process and soil vapor extraction for eliminating contaminants in soil or rock pore, and pneumatic fracturing for the improvement of permeability of rock mass. For the purpose of appropriate analysis of groundwater-gas flow, this study presents an unsteady-state multi-phase FEM fracture network simulator. Numerical simulation has been also conducted to investigate the hydraulic head distribution and air tightness around Ulsan LPG storage cavern. The recorded hydraulic head at the observation well Y was -5 to -10 m. From the results obtained by the developed model, it shows that the discrete fracture model yielded hydraulic head of -10 m, whereas great discrepancy with the field data was observed in the case of equivalent continuum modeling. The air tightness of individual fractures around cavern was examined according to two different operating pressures and as a result, only several numbers of fractures neighboring the cavern did not satisfy the criteria of air tightness at 882 kPa of cavern pressure. In the meantime, when operating pressure is 710.5 kPa, the most areas did not satisfy air tightness criteria. Finally, in the case of gas leaking from cavern to the surrounding rocks, the resulted hydraulic head and flowing pattern was changed and, therefore, gas was leaked out from the cavern ceiling and groundwater was flowed into the cavern through the walls.

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Proposal for a modified classification of isolated zygomatic arch fractures

  • Jung, Seil;Yoon, Sihyun;Nam, Sang Hyun
    • 대한두개안면성형외과학회지
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    • 제23권3호
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    • pp.111-118
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    • 2022
  • Background: Although the zygomatic arch is an important structure determining facial prominence and width, no consensus exists regarding the classification of isolated zygomatic arch fractures, and the literature on this topic is scarce. To date, five papers have subdivided zygomatic arch fractures; however, only one of those proposed classifications includes the injury vector, although the injury vector is one of the most important factors to consider in fracture cases. Furthermore, the only classification that does include the injury vector is too complicated to be suitable for daily practice. In addition, the existing classifications are clinically limited because they do not consider greenstick fractures, nondisplaced fractures, or coronoid impingement. In the present study, we present a rearrangement of the previously published classifications and propose a modified classification of isolated zygomatic arch fractures that maximizes the advantages and overcomes the disadvantages of previous classification systems. Methods: The classification criteria for isolated zygomatic arch fractures described in five previous studies were analyzed, rearranged, and supplemented to generate a modified classification. The medical records, radiographs, and facial bone computed tomography findings of 134 patients with isolated zygomatic arch fractures who visited our hospital between January 2010 and December 2019 were also retrospectively analyzed. Results: We analyzed major classification criteria (displacement, the force vector of the injury, V-shaped fracture, and coronoid impingement) for isolated zygomatic arch fracture from the five previous studies and developed a modified classification by subdividing zygomatic arch fractures. We applied the modified classification to cases of isolated zygomatic arch fracture at our hospital. The surgery rate and injury severity differed significantly from fracture types I to VI. Conclusion: Using our modified classification, we could determine that both the injury force and the injury vector meaningfully influenced the surgery rate and the severity of the injuries.

CNKI 검색을 통한 척추 압박 골절의 최신 한의 치료 방법 연구 (A Review of Recent Studies for Treatment of Compression Fracture Using CNKI Database)

  • 김동은;김정훈;정진수;유선애;조성우
    • 한방재활의학과학회지
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    • 제27권3호
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    • pp.1-12
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    • 2017
  • Objectives The purpose of this research is to investigate recent clinical treatment of Traditional Chinese Medicine for Compression Fracture. Methods We searched recent clinical studies about Oriental Medicine treatment in traditional chinese medical journals for Compression Fracture through China National Knowledge Infrastructure (CNKI). Clinical articles published from 2012 to 2016 were analyzed. This study examined the authors, published years, types of study, number of sample, criteria for evaluation, periods, purposes of study and classified articles by techniques of treatment. Results 23 papers were selected from 98 studies. Most of articles were classified as RCT. The techniques of treatment were herb medicine, herb medicine apply therapy, herb medicine fumigation therapy, Dao yin exercise. Conclusions Various and valuable studies about treatment of Compression fracture performed in chinese medicine. And more studies using various treatment needed for Korean Medicine development.