대퇴골 간부 골절시 사용한 금속물의 금속부전(Metal failure)의 기전에 대한 연구

인주철,안면환,안종철,서재성,전춘배 영남대학교 의과대학 1990 Yeungnam University Journal of Medicine Vol.7 No.1

1983년 5월부터 1989년 9월까지 본 영남의료원 정형외과에 대퇴골 간부골절시 사용한 금속 내 고정물의 금속 부전으로 입원한 경우 중 부전된 금속의 표면관찰이 가능한 8례에 대한 임상적 고찰 및 부전된 금속 파손 표면의 관찰을 통해 확인한 파손 원인을 요약하면 다음과 같다. 1. 금속 부전이 발생 내고정물의 종류는 압박 금속판 5례, Jewett nail 1례, Rowe plate screw 1례, interlocking nail 1례였다. 2. 금속 부전의 임상적 추정에 의한 원인으로는 반대편 피질골 결손 5례, 부적절한 위치선정 1례 및 부적절한 금속선택 1례였다. 3. 금속 내고정후 금속 부전이 되기까지의 기간을 보면, 4개월이 1례, 6개월에서 12개월사이가 6례, 3년이 1례였다. 4. 부전된 내고정물의 파손면 관찰을 통해 학인한 금속부전의 원인을 보면, 첫째, impact failure 1례 둘째, fatigue failure 6례 machining mark가 있어 이것이 stress riser로서 역할을 한 것으로 보이는 경우가 4례였으며, 이의 형태는 low consistent cyclic fatigue failure와 irregular cyclic fatigue failure의 형태를 관찰할 수 있었다. 셋째, Stress corrosion crack 1례를 관찰할 수 있었다. 5. 316L Stainless Steel은 내부식성이 좋은 금속이지만 fretting에 의해 특유의 부동태 피막이 손상되면 pitting corrosion을 일으키며 경우에 따라서는 파손의 기점으로 작용되어 failure의 주요 원인이 되기도 한다. 6. screw hole의 가공시 기계에 의한 손상 및 기구(implant) 제조 과정중 손상이 plate의 failure를 유발하는 중요한 원인이 될 수도 있다. 기계에 의한 손상은 응력을 집중시키므로 plate가 파손되기 쉽게 한다. 이상의 결과 임상적 추정에 의한 원인 이외에도 부전된 금속파손면 관찰을 통해 중요한 다른 원인을 찾을 수 있었으므로, 금속부전의 예방을 위해 앞으로 이 방향으로의 계속적인 연구가 필요할 것으로 사료된다. The author fractographically analyized the cause of metal failure(the first time this procedure has been used for this metal failure)and also analyized it clinically. In this study, I selected eight cases which have been analyized fractographically. In all these cases, the analysis was done after treatment of metal failure of implants internally fixed to femur shaft fractures at the Department of Orthopedic Surgery, Yeung-Nam University Hospital during the six year period from May 1983 to September 1989. 1. Metal failure occured in five dynamic-compression plates, one Jewett nail, one screw in Rowe plate, and one interlocking nail. 2. The clinical cause of metal failure was deficiency of medial butress in five cases, incorrect position of implant in one case, and incorrect selection of implant in two cases. 3. The time interval between internal fixation and metal failure was four months in one case, between five months to twelve months in six cases, three years in one case. 4. The fractographically analytical cause of metal failure was ; first, impact failure, one case, second, fatigue failure, six cases, machining mark(stress liser), four cases type : low consistent cyclic fatigue failure irregular cyclic fatigue failure third, stress corrosion crack, one case. 5. 316L Stainless Steel has good resistance to corrosion. However, when its peculiar surface film is destroyed by fretting, it shows pitting corrosion. This is, perhaps, the main cause of metal failure. 6. It is possible that mechanical injury occured in implants during the manufacturing of implants or that making a screw hole is the main cause of metal failure.

INVESTIGATION OF FATIGUE STRENGTH AND FAILURE MODE IN CFRP LAMINATES UNDER FRETTING CONDITIONS

SHIN, Hyung-Seop,KIM, Moon-Saeng ENGINEERING TRIBOLOGY RESEARCH INSTITUTE KYUNGPOOK 1998 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.1998 No.-

Fretting fatigue tests were carried out to investigate the fatigue behavior of CFRP laminates under fretting conditions. Influences of the stacking sequence of laminates and the contact stress on the fatigue strength of specimens were studied. A special fixture was designed to apply a contant stress transversely to the specimen. As a result, the fretting fatigue caused a significant drop of the fatigue strength in CFRP laminates, as compared with the case of the plain fatigue. The B type specimen of 【±45/0₂/±45/0₂】sym represented a higher fatigue strength than the A type one of【0₂/90₂/0₂/90₂】sym, against both plain fatigue and fretting fatigue. Effects of contact stress on the fatigue strength showed a different behavior according to the stacking sequence of laminates, and it appeared only on the A type specimen. The failure mode under fretting fatigue showed different appearances depending upon the stacking sequence and the applied fatigue dtress level. The fractography could explain well the fretting behaviors of CFRP laminates.

Modeling of wind-induced fatigue of cold-formed steel sheet panels

Rosario-Galanes, Osvaldo,Godoy, Luis A. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.2

Wind-induced failure around screwed connections has been documented in roof and wall cladding systems made with steel sheet cold-formed panels during high wind events. Previous research has found that low cycle fatigue caused by stress concentration and fluctuating wind loads is responsible for most such failures. A dynamic load protocol was employed in this work to represent fatigue under wind effects. A finite element model and fatigue criteria were implemented and compared with laboratory experiments in order to predict the fatigue failure associated with fluctuating wind loads. Results are used to develop an analytical model which can be employed for the fatigue analysis of steel cold-formed cladding systems. Existing three dimensional fatigue criteria are implemented and correlated with fatigue damage observed on steel claddings. Parametric studies are used to formulate suitable yet simple fatigue criteria. Fatigue failure is predicted in different configurations of loads, types of connections, and thicknesses of steel folded plate cladding. The analytical model, which correlated with experimental results reported in a companion paper, was validated for the fatigue life prediction and failure mechanism of different connection types and thicknesses of cold-formed steel cladding.

Modeling of wind-induced fatigue of cold-formed steel sheet panels

Osvaldo Rosario-Galanes,Luis A. Godoy 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.2

Wind-induced failure around screwed connections has been documented in roof and wall cladding systems made with steel sheet cold-formed panels during high wind events. Previous research has found that low cycle fatigue caused by stress concentration and fluctuating wind loads is responsible for most such failures. A dynamic load protocol was employed in this work to represent fatigue under wind effects. A finite element model and fatigue criteria were implemented and compared with laboratory experiments in order to predict the fatigue failure associated with fluctuating wind loads. Results are used to develop an analytical model which can be employed for the fatigue analysis of steel cold-formed cladding systems. Existing three dimensional fatigue criteria are implemented and correlated with fatigue damage observed on steel claddings. Parametric studies are used to formulate suitable yet simple fatigue criteria. Fatigue failure is predicted in different configurations of loads, types of connections, and thicknesses of steel folded plate cladding. The analytical model, which correlated with experimental results reported in acompanion paper, was validated for the fatigue life prediction and failure mechanism of different connection types and thicknesses of cold-formed steel cladding.

십자형 필릿 용접부에서의 피로파괴 형상과 특성

이용복,정준기,박상흡,Lee, Yong-Bok,Chung, Joon-Ki,Park, Sang-Heup 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.4

The proportion of the welding in the production process of machinery, buildings and marine structures is increasing and the joining are mainly conducted by butt and fillet weld. In the case of fillet weld, the shape of structures is complicated depending on the constraint on the geometry of the structures, therefore, the full penetration is mostly difficult. Accordingly, it is necessary to establish safe and economical criteria of design of the structures through the strength based on the penetration state of the fillet weld. Patterns of fatigue failure in cruciform fillet weld jont appear in the form of the root, toe and mixed failure. In the case of toe and mixed failure, the fatigue strength is higher than root failure. Therefore, we have to make the enough depth of penetration or perform the welding work through improving the fatigue strength of cruciform joints in welded structures. So it is necessary to optimize the penetrated depth in the range of the possible mixed failure and find the way in the cost-effective design to lessen the amount of the welding work.

드럼 세탁기 Spider의 피로수명 신뢰성 평가에 대한 연구

이성민(Seongmin Lee),조상봉(Sangbong Cho),조성진(Seongjin Jo),김영수(Youngsoo Kim),강동우(Dongwoo Kang),정연수(Younsu Jung),정보선(Bosun Chung) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월

The spider of a drum washing machine receives the repeated fatigue loadings during laundering. Although the spider is designed statically safely, it often happens fatigue failure. Therefore it requires the safe design for fatigue and needs the prediction of quantitative fatigue life. The S-N diagram for a spider material is developed by fatigue test and statistical analysis. The stresses are measured directly from strain gages on the spider. To predict the fatigue life of spider, the rainflow counting method and Miner"s rule are used. The data for fatigue life are analyzed statistically. From these data, reliability estimation for fatigue life can be done and also, equivalent fatigue life can be obtained. It will be applied to make and improve to a short period for design and prototype test.

Structural system reliability-based design optimization considering fatigue limit state

Young-Joo Lee,Nophi Ian D. Biton 국제구조공학회 2024 Smart Structures and Systems, An International Jou Vol.33 No.3

The fatigue-induced sequential failure of a structure having structural redundancy requires system-level analysis to account for stress redistribution. System reliability-based design optimization (SRBDO) for preventing fatigue-initiated structural failure is numerically costly owing to the inclusion of probabilistic constraints. This study incorporates the Branchand- Bound method employing system reliability Bounds (termed the B³ method), a failure-path structural system reliability analysis approach, with a metaheuristic optimization algorithm, namely grey wolf optimization (GWO), to obtain the optimal design of structures under fatigue-induced system failure. To further improve the efficiency of this new optimization framework, an additional bounding rule is proposed in the context of SRBDO against fatigue using the B3 method. To demonstrate the proposed method, it is applied to complex problems, a multilayer Daniels system and a three-dimensional tripod jacket structure. The system failure probability of the optimal design is confirmed to be below the target threshold and verified using Monte Carlo simulation. At earlier stages of the optimization, a smaller number of limit-state function evaluation is required, which increases the efficiency. In addition, the proposed method can allocate limited materials throughout the structure optimally so that the optimally-designed structure has a relatively large number of failure paths with similar failure probability.

Effects of stretching and cycling on the fatigue behavior of polymer-supported Ag thin films

Sim, G.D.,Lee, Y.S.,Lee, S.B.,Vlassak, J.J. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.575 No.-

The fatigue behavior of silver films on polyethylene-terephthalate substrates is studied for various levels of film thickness, pre-stretch, sample width, and applied strain range. Films with large pre-stretch have a shorter fatigue life, with failure caused by strain localization (films thicker than 100nm) or intergranular crack formation (100nm film). There is a significant effect of film thickness on how the strain range affects the fatigue life - we observe 'smaller is better' behavior for films subjected to a total strain range of Δε<SUB>t</SUB>=1.0%, while the opposite is true when the total strain range increases to 2.0%. We attribute this difference to a shift in failure mechanism with strain amplitude from typical fatigue failure to a more ductile-type failure. Our experimental results are well described by the Coffin-Manson relationship and a failure mechanism map is drawn based on the experimental results. Considering stretchability and long-term reliability, design suggestions are made to optimize the fatigue life of coatings subjected to uniaxial stretch and fatigue.

Overload failure curve and fatigue behavior of spot-welded specimens

Lee, Hyungyil,Kim, Nahmho,Lee, Tae Soo Elsevier 2005 Engineering fracture mechanics Vol.72 No.8

<P><B>Abstract</B></P><P>The mechanical behavior of a spot-welded specimen is generally approached in angles of overload and fatigue failures. The primary issue in an overload failure is to establish an overload failure criterion. Fatigue failure of spot-welded specimens can be dealt with a fracture parameter, since a spot-weld forms a singular geometry of external crack type. In this work, we express the limit loads in terms of base metal yield strength and specimen geometries. We then present a master overload failure curve for a single spot-welded specimen in a mixed-mode load domain. The coordinates of the domain are normalized by the limit loads of single spot-welded specimens. Recasting the load vs. fatigue life relations experimentally obtained, we attempt to predict the fatigue life of various spot-weld specimens with a single parameter denoting the equivalent stress intensity factor. This crack driving parameter is demonstrated to successfully describe the effects of specimen geometry and load type in an inclusive manner. The suggested fatigue life formula for a single spot-weld can be used in the assessment of spot-welded panel structures as the fatigue strength of multi-spots is eventually determined by that of each single spot-weld.</P>

Rehabilitation Intervention for Individuals With Heart Failure and Fatigue to Reduce Fatigue Impact: A Feasibility Study

Young Joo Kim,Jennifer C. Radloff,Patricia A. Crane,Linda P. Bolin 대한재활의학회 2019 Annals of Rehabilitation Medicine Vol.43 No.6

Objective To investigate feasibility of recruitment, tablet use in intervention delivery, and use of self-report outcome measures and to analyze the effect of Energy Conservation plus Problem-Solving Therapy versus Health Education interventions for individuals with heart failure-associated fatigue. Methods This feasibility study was a block-randomized controlled trial involving 23 adults, blinded to their group assignment, in a rural southern area in the United States. Individuals with heart failure and fatigue received the interventions for 6 weeks through videoconferencing or telephone. Participants were taught to solve their fatigue-related problems using energy conservation strategies and the process of Problem-Solving Therapy or educated about health-related topics. Results The recruitment rate was 23%. All participants completed the study participation according to their group assignment, except for one participant in the Energy Conservation plus Problem-Solving Therapy group. Participants primarily used the tablet (n=21) rather than the phone (n=2). Self-report errors were noted on Activity Card Sort (n=23). Reported fatigue was significantly lower for both the Energy Conservation plus Problem-Solving Therapy (p=0.03, r=0.49) and Health Education (p=0.004, r=0.64) groups. The Health Education group reported significantly lower fatigue impact (p=0.019, r=0.48). Participation was significantly different in low-physical demand leisure activities (p=0.008; r=0.55) favoring the Energy Conservation plus Problem-Solving Therapy group. Conclusion The recruitment and delivery of the interventions were feasible. Activity Card Sort may not be appropriate for this study population due to recall bias. The interventions warrant future research to reduce fatigue and decrease participation in sedentary activities (Clinical Trial Registration number: NCT03820674).