복합재료 적층판의 피로수명 예측을 위한 일정수명선도 연구

박태영,김명준,장병욱,이정진,박정선 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11

본 논문에서는 복합재료 적층판의 비선형 피로 거동을 묘사하기 위한 새로운 일정수명선도 식을 제안하였다. 또한 최근 제안되어 일반적으로 사용되고 있는 일정수명선도 모델들을 복합재료의 피로 데이터에 적용하여 제안된 일정수명선도 모델에 대한 예측 정확도를 비교 검증하였다. 이때 예측 정확도는 일정 수명선도 생성에 사용되지 않은 임의의 하중 조건에 대한 응력-수명 선도를 예측 후 실제 데이터와 비교하여 정량적으로 산출하였으며, 복합재료 피로 시험 데이터는 문서화된 데이터베이스를 통해 획득하였다. 연구 결과 제안된 일정수명선도는 비교적 간단한 계산 과정을 통해 현재 가장 정확도 높은 부분선형 일정수명선도만큼이나 정확한 응력-수명 선도를 예측함을 확인하였다. In this study, a new constant life diagram(CLD) formulation is developed to describe the nonlinear fatigue behavior of composite laminates. Most commonly used and recently proposed CLDs applied on composite materials fatigue data are presented and their predictive accuracy are compared with the proposed model. The accuracy of estimation is quantified by comparing actual fatigue data and the predicted S-N curve for arbitrary load condition for which no experimental data exists. Composite material fatigue data from a number of well documented databases were used. Finally, the results revealed that the proposed model predicted relatively accurate S-N curves with simple calculate process as well as currently the most accurate piecewise linear model.

콘크리트궤도 장대레일의 휨 피로수명 평가

성덕룡(Deok-Yong Sung),태성식(Sung-Sik Tae),박광화(Kwang-Hwa Park),강윤석(Sun-Yong Kong),박용걸(Yong-Gul Park) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7

장대레일 교체주기는 자갈궤도 레일두부 표면요철과 레일 휨피로의 상관관계 분석을 통해 산정되었다. 본 연구에서는 실물 레일 휨 피로시험을 통한 레일의 S-N선도, 국내 도시철도(서울메트로) 콘크리트궤도에서 발생하는 레일 휨응력 예측식, Haibach's rule을 통해 콘크리트궤도 장대레일의 휨 피로수명을 평가하였다. 여기서, 레일용접방법별 S-N선도와 레일표면요철, 열차운행속도가 고려되었다. 또한, S-N선도 파괴확률 1%, 0.1%, 0.01%를 고려한 휨 피로수명을 비교하였다. 따라서 본 연구에서는 콘크리트궤도 장대레일의 휨 피로수명을 제안하였다. It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In this study, based on the results of bending fatigue tests of rail and results of measuring tests in situ of rail bending stress, this study estimated the bending fatigue life of welded rail in concrete track, adopting a Haibach's rule. The bending fatigue life of CWR considered the rail surface irregularity, train speed and the S-N curve by types of rail welding. In addition, this study estimated it for the fracture probability 1%, 0.1%, 0.01%. Therefore, this study proposed bending fatigue life of CWR in concrete track.

드럼세탁기 축계의 피로수명 평가

김대진(D. J. Kim),위우택(W. T. We),석창성(C. S. Seok),이근호(G. H. Lee),민제홍(J. H. Min) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월

To estimate the fatigue life of flange-shaft assembly, fatigue test for flange material and bending fatigue test for flange-shaft assembly were conducted. Also, finite element analysis for flange-shaft assembly was conducted. Then, we have changed the obtained P-N curve to S-N curve using the finite element analysis results which were stress values at the location of fracture. The S-N curve of flange material itself was almost consistent with that of flange-shaft assembly, so it seems that the fatigue life of flange-shaft assembly could be estimated by using S-N curve for flange material and the stress at the location of fracture calculated by finite element methods.

샤시부품에 대한 내구해석용 용접부 피로물성 도출에 관한 연구

전태룡(Taeryong Jeon),구자석(Jasuk Koo),최승렬(Seungryul Choi),안병재(Byungjae Ahn) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

The fatigue properties curve (S-N curve)of the chassis components is presented in this paper. The structural stress of weld joints edge is used for the amplitude stress of S-N curve. The structural stress is consistent with elementary structural mechanics theory and provides an effective measure of a stress state that pertains to fatigue behavior of welded joints in the form of both membrane and bending components. In order to consider the effect of mean stress, the mean stress correction has been calculated according to the FKM guideline. The S-N curve of standard fatigue specimens is compared with the S-N curve obtained from fatigue test of chassis components. The S-N curve from standard fatigue specimens is well correlated with the SN curve of chassis components. Therefore, the S-N curve obtained from standard fatigue specimens is expected to improve the reliability of the fatigue analysis of the chassis components.

용접부 피로물성 도출에 관한 연구

전태룡(Taeryong Jeon),구자석(Jasuk Koo),안병재(Byungjae Ahn),권혁선(Hyuksun Kwon) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

The fatigue properties curve (S-N curve) of the chassis components is presented in this paper. The structural stress of weld joints edge is used for the amplitude stress of S-N curve. The structural stress is consistent with elementary structural mechanics theory and provides an effective measure of a stress state that pertains to fatigue behavior of welded joints in the form of both membrane and bending components. In order to consider the effect of mean stress, the mean stress correction has been calculated according to the FKM guideline. The S-N curve of standard fatigue specimens is compared with the S-N curve obtained from fatigue test of chassis components. The S-N curve from standard fatigue specimens is well correlated with the S-N curve of chassis components. Therefore, the S-N curve obtained from standard fatigue specimens is expected to improve the reliability of the fatigue analysis of the chassis components

수정된 S-N 곡선과 랜덤 변형률 이력을 이용한 피로수명 예측

유수호(Sooho Yoo),김강욱(Kangwook Kim),이동석(Dongseok Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

When the Car run on the road, assembled part support axle force and moment. In the FEM analysis of assembled part, the technique to predict Fatigue life and calculate stress need to apply correct force. In this study we use the stabilizer-bar during the experimentation for module road simulator using a full car road data generate crack. Strain gauge is attached to cracked point and estimates the strain history. The fatigue analysis will be implemented after calculate random stress history. S-N curve will be modified by cracked mode and compare to current a part-test-result for the confident fatigue analysis. Additional, damage analysis practice usually used S/W and numerical analysis method with measured strain data.

Ventilated Disk Brake의 피로 수명 해석

박재실(J. S. Park),이영훈(Y. H. Lee),석창성(C. S. Seok),김성호(S. H. Kim),이동근(D. G. Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3

Brakes in cars and trucks are safety parts. Requirements not only in performance but also in comfort, serviceability and working lifetime are high and rising. In this study, we used the ventilated disk brake in 11 ton-bus. Mechanical stress analysis and thermal stress analysis were performed using ABAQUS software. Especially, characteristics of the rotor were analyzed in considering deceleration, initial temperature and intial velocity of brake. And tensile test and fatigue test were performed on those of brake. Form the comparing the results of experiment and FEM analysis, the standard for durability of brake was presented.

레일체결장치용 방진패드의 피로거동에 관한 해석적 연구

최정열 국제문화기술진흥원 2021 The Journal of the Convergence on Culture Technolo Vol.7 No.2

본 연구에서는 레일체결장치용 방진패드의 사용수명 및 스프링강성을 평가하고자 비선형 재료모델 및 피로하중조건을 적용한 유한요소해석을 수행하였다. 피로해석 결과, 초기조건 대비 스프링강성의 변화율은 약 16%로 나타나 피로경화가 발생된 것으로 분석되었다. 방진패드의 길이방향으로 발생되는 응력은 중앙부와 외곽부(Edge)의 발생응력의 차이가 약 10배 이상 발생되었다. 또한 중앙부 보다 외곽 경계부의 등가응력이 2배 이상 크게 발생하는 것으로 분석되었다. 따라서 실제 사용조건에서 방진패드의 손상 및 변형 취약부는 방진패드의 모서리부분인 것으로 분석되었다. 피로해석을 통해 산출된 반복횟수에 따른 방진패드의 등가응력을 이용하여 방진패드의 피로수명선도를 도출하였다. 본 연구에서 도출한 방진패드의 피로수명선도를 이용하여 향후 다양한 하중조건에서 방진패드의 등가응력을 산출하여 해당조건에서의 피로수명을 예측하는 데에 활용이 가능할 것으로 판단된다. In this study, a finite element analysis was performed applying a nonlinear material model and fatigue load conditions to evaluate the service life and spring stiffness of the resilient pad for rail fastening system. As a result of the fatigue analysis, the rate of change in spring stiffness compared to the initial condition was about 16%, indicating that fatigue hardening occurred. As for the stress generated in the longitudinal direction of the resilient pad, the difference between the stress generated at the center and the edge was about 10 times or more. In addition, it was analyzed that the equivalent stress of the outer boundary was more than twice as large as that of the central part. Therefore, it was analyzed that the damage and deformation of the resilient pad are the corners of the resilient pad under actual service conditions. The fatigue life diagram of the resilient pad (S-N curve) was derived using the equivalent stress of the resilient pad according to the fatigue cycles. Using the fatigue life diagram of the resilient pad derived in this study, it is considered that it can be used to predict the fatigue life under the relevant conditions by calculating the equivalent stress of the resilient pad under various load conditions.

국내 철도 레일의 휨 피로거동 분석

성덕룡(Sung Deok-Yong),김박진(Kim Bag-Jin),박광화(Park Kwang-Hwa),경갑수(Kyung Kab-Soo),박용걸(Park Yong-Gul) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월

The replacement period criteria of rail according to the accumulated passing tonnage was estimated by the bending fatigue life of rail. In order to estimate the bending fatigue life, it basically needs to analyze bending fatigue behaviour on the rail. This study performed a bending fatigue test for 50㎏/m and 60㎏/m rails, and these were distinguished by new and used rails, and the types of rail welding such as base material welding, thermite welding, and gas pressure welding. Also, it analyzed the fractured surface, the position of initial crack, and the bending fatigue behaviour(S-N curve). Therefore, it achieved S-N curve for new and used rail according to the types of rail welding. It might be made full use of essential data in order to estimate rail the bending fatigue life according to accumulated passing tonnage.

저비중 SMC 외장패널의 피로특성 평가

김은성(Eun-sung Kim) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.5

A research for application of LDSMC(Low Density Sheet Molding Compound) composite is in progress for lightening the weight. This paper has performed fatigue test and simulation of external panel for Korean commercial vehicle. Before the fatigue test, static test was carried out. From the test, the structural safety was investigated using Goodman diagram. After the static test performance, the fatigue test was conducted at a range of load frequency 5Hz, a stress ratio(R) of 0.05 and an endurance limit of 10<SUP>6</SUP> to obtain the S-N curve. The S-N curve is applied to the fatigue analysis of the external panel assembly. The result of FEM analysis was in accord with the experimental result within 83% confidence. It showed that the process to set up the safety range of allowable error is required in process of the design and simulation verification.