http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
신현호,김종봉 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
The correction functions that can be used to determine the stress state of a flattened disk specimen in diametral testing are provided by referring to the analytical solutions for arc- and point-loaded circular specimens. The stress components at three important locations in the flattened specimen (with varying degrees of truncation, w) were obtained numerically by finite element analysis, and compared with the analytical solutions at the center of the arc- and point-loaded specimens. The correction functions, which are provided as a function of w, can be useful tools for the analysis of the stress state and for the design of the flattened disk specimen in diametral testing.
Wee, J.W.,Choi, B.H. Pergamon Press ; Elsevier Science Ltd 2016 International journal of solids and structures Vol.97 No.-
Because of the characteristic of high triaxial stress of a circular notched bar (CNB) specimen under tensile loads, it is a promising candidate for accelerated durability testing of high-density polyethylene (HDPE). To understand the slow crack growth (SCG) behavior of HDPE using a CNB specimen, it is practically important to base the evaluation of the SCG model using a CNB specimen on the concept of fracture mechanics. In this study, the SCG kinetics of HDPE with a CNB specimen is modeled on the basis of the concept of an axisymmetric crack layer (CL) system. CL theory is applied to the modeling of the axisymmetric SCG considering the geometry of the CNB specimen. Green's functions of the stress intensity factor and crack opening displacement of the CNB specimen are calculated in order to simulate the CL kinetics. The obtained Green's functions are also utilized to compute the thermodynamic forces for both the crack growth and the CL growth, and a generalized CL growth algorithm is developed. A parametric study of several key input parameters is conducted for validation of the developed CL model. In addition, actual SCG generated experimentally is simulated using the developed model, and it is found that the actual test results can be successfully simulated using the developed CL model.
유한요소해석기법을 이용한 토크 시편의 축 오열 영향 분석
김주희(Ju-Hee Kim),김윤재(Yun-Jae Kim),허용학(Yong-Hak Huh) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.11
본 논문은 3 차원 유한요소해석 기법을 이용하여 토오크 시험을 위한 표준시험시편의 각도 및 동심 오열이 시편의 응력과 변형률 변화에 미치는 영향을 분석하였다. 해석 결과의 정량적 비교를 위해 각, 동심 및 복합 축 오열에 대한 평균 굽힘 변형률을 적용하였으며, 시편 형상에 따른 축 오열 영향을 확인하기 위해 환봉형 시편과 튜브형 시편에 대해 각각 유한요소해석을 실시하였다. 해석결과로부터 얻어진 변형률과 응력의 변화로 축 오열의 종류와 방향을 예측하는 일반적인 기준을 제시하였으며, 초기 항복조건을 적용하여 축 오열이 토오크 시편의 초기 항복 모멘트에 미치는 영향을 분석하였다. Using three-dimensional (3-D) FE analyses, this paper provides a method for analyzing the effects on stresses and strains produced by angular and concentric misalignment of a test specimen for a torsion test. To quantitativele compare of the FE results, the average bending strain for the angular, concentric, and combined misalignment was proposed. To verify the effects of axial misalignment of the test specimens, we used both circular and tubular specimens. From the FE results, we proposed general predictions for the effects caused by the various types of axial misalignment and its direction. In addition, we confirmed the effect of initial yielding moment based on the initial yielding condition for axial misalignment of specimens in torsion tests.
Analysis of Bearing Capacity of Circular Concrete Filled CFRP-Steel Tubular Beam-Column
Kuan Peng,Yongbo Shao,Qingli Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.1
In practice, it is common for circular concrete-filled CFRP-steel tube (C-CF-CFRP-ST) member severing under eccentric load, but there are few related investigations on its mechanical behavior currently. In this study, experimental study and finite element analysis are employed to reveal the static behavior of circular concrete filled CFRP-steel tube under eccentric compression. Total 32 C-CF-CFRP-ST specimens, taking the slenderness ratio (λ) and eccentric ratio (e) as principal parameters, were designed and tested firstly, obtaining the failure modes, N-um curve and the strains in the steel tube and CFRP. It was found that the damage of concrete became more serious with the decrease of the slenderness ratio but got mitigated with the increase of eccentricity. Additionally, it was indicated that the N-um curve of C-CF-CFRP-ST consisted of three stages, namely elastic stage, elastic-plastic stage and plastic stage. In the elastic-plastic stage, the damage is gradually accumulated in CFRP and concrete, and the specimens finally exhibited ductile failure in the end of plastic stage. In the entire loading process, CFRP has almost same strains compared to the steel tube. Following the experimental study, finite element analysis was conducted to investigate the static behavior of C-CF-CFRP-ST comprehensively. The proposed finite element model reproduced the compressive behavior of C-CF-CFRP-ST, in terms of failure modes and N-um curves. The influence of material strength, layers of CFRP and steel ratio on the static behavior of C-CF-CFRP-ST specimens were then studied through numerical parametric study. In the end, equations for predicting the bearing capacity of C-CF-CFRP-ST are proposed, and the predicted static strengths of the specimens are basically consistent with the experimental results.
Kim, I.,Zhao, Y.,Choi, B.H.,Lee, J.M.,Lee, K.S.,Lee, J.M. Pergamon Press ; Elsevier Science Ltd 2013 Engineering fracture mechanics Vol.108 No.-
The effects of various misalignments of circular notched bar (CNB) specimens on the fatigue crack propagation behavior of pipe grade polyethylene were investigated by finite element analyses. Generally, as the misalignments increased, the asymmetric crack growth accelerated with a consequent decrease in the time taken to reach the critical stress intensity factors. It was therefore confirmed that the lifetime to failure of CNB specimens varies noticeably when they are misaligned. Going by our study results, the fatigue crack growth behavior of CNB specimens, including their lifetime estimations, should be considered by addressing the effects of their misalignments.
축 정렬 이상이 토오크 부재의 응력 변화에 미치는 영향
김주희(Ju-Hee Kim),김윤재(Yun-Jae Kim),허용학(Yong-Hak Heo),제진호(Jin-Ho Je),홍석표(Seok-Pyo Hong) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Using a three-dimensional (3-D) FE analysis, this paper provides the stress variation of the standard test specimen for the torsion test, as well as a method for analyzing effects of misalignment under the angular and concentric misalignment. For verification, FE analysis is performed, which is designed for the perfectly full-model. To verify FE results of the torsion-controlled fatigue test specimen, we compared the FE-results and theoretical results. Additionally, three kinds of misalignment (angular, concentric and combined misalignment) are applied to the circular and tubular specimens to show effects of misalignments in the FE analysis. The present results will provide valuable information for designing shafts for every kind of mechanical system under torsional force.
비틀림 시험에 대한 표준시험시편 형상 및 축 정렬 이상 영향 분석
김주희(Ju-Hee Kim),김윤재(Yun-Jae Kim),허용학(Yong-Hak Heo),제진호(Jin-Ho Je) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Using a three-dimensional (3-D) FE analyses, this paper provides the shape optimization of the standard test specimen for the torsion test, as well as a method for analyzing effects of misalignment under the angular and concentric misalignment. For verification, FE analysis is performed, which is designed for the perfectly full-model. To optimize the design shape of the torsion-controlled fatigue test specimen, we performed sensitivity analysis using shape parameters. Additionally, two kinds of misalignment (angular misalignment and concentric misalignment) are applied to the circular and tubular specimens to show effects of misalignments in the FE analysis. The present results will provide valuable information for designing shafts for every kind of mechanical system under torsional force.
배관용 고밀도 폴리에틸렌재의 환형노치시험편을 이용한 피로균열거동평가
Yongjian Zhao,최병호(Byoung-Ho Choi),이기수(Ki-Soo Lee) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
For evaluating the crack resistance of pipe grade polyethylene, several standard tests have been proposed but most industrial standards on crack resistance are not adequate for recently developed high performance pipe grade polyethylene due to extremely long time to test. Recently, a circular notched specimen (CNS) has been selected for studying the characteristics of the crack resistance of pipe grade polyethylene as a part of understanding quasi-brittle failure. CNS can create tri-axial stress status around the crack tip, so it can be good specimen geometry for developing an accelerated test. In this study, four types of pipe grade polyethylene were chosen and tested under variable fatigue loading conditions with various notch depths. The fatigue characteristics of four polyethylene were evaluated, and the fracture surface of CNS after failure is analyzed by optical microscope and scanning electron microscope (SEM) to evaluate the fracture mechanism of pipe grade polyethylene.