미소 결함을 가진 S35C 환봉재의 피로균열 발생수명 예측

裵原鎬 慶一大學校 1997 論文集 Vol.14 No.2

A prediction method of crack initiation life of round bar in S35C steel which has a small artificial defect was studied. Crack growth rate can be expressed by stress intensity factor range, ΔK or σm ℓ. In this paper, these equations were examined to evaluate fatigue initiation life and the elastic strain-life relation which has known to Basquin's equation was examined. Paris equation was useful to predict for crack initiation life simply and easy, but it has some limitation to adopt. This equation would be expressed different type with the size of specimen or notch and the increase tendency of stress at notch root. This equation suitable to express the large crack growth rate, but the crack initiation life could be obtained during the small crack growth. Nisitami equation differentials expressed with crack length, and in early stage of crack growth, the measuring of crack length would be difficult. The crack initiation life was obtained easy by Basquin's equation, and the result of estimated life was well corresponded with the value of fatigue experiment. Basquin's equation could be obtain easy and it does not affected by the sort of materials and size of defect. So that, to predict the crack initiation life the method of Basquin's equation was most recommendable.

자기치유 콘크리트 성능평가를 위한 투수시험방법의 신뢰성 및 적합성 검증

배원호(Bae, Won Ho),김성우(Kim, Sung Woo),이광명(Lee, Kwang Myong),신경준(Shin, Kyung Joon) 한국콘크리트학회 2016 한국콘크리트학회 학술대회 논문집 Vol.28 No.1

표면균열의 피로균열 진전 거동에 대한 통계학적 고찰

裵原鎬 경일대학교 산업기술연구소 1991 産業技術硏究所 論文集 Vol.5 No.-

Fatigue crack growth behavior of surface crack in SB41 steel plate was investigated by statistically. Fatigue test were carried out for four stresses range, the one of the maximum stress was lower than the yield strength, and another was nearly to the yield strength and the other two were higher than the yield strength. The data of crack growth rate were scattered more widely with the increasing of stress intensity factor range, and the distribution was expressed by Log-normal distribution or Weibull distribution at constant level of stress intensity factor range. The tendency of variation about constant C and exponent n of Paris' equation to express the crack growth rate were also examined with the varying of stress intensity factor range. The Paris equation's constant C and exponent n were expressed different varying tendency with the increasing of stress intensity factor range at the each three types of maximum stress level. The constant C and exponent n of Paris' equation had very close relation, the constant C were lineally decreased with the increasing of exponent n and increased with decreasing of exponent n.

斜面 경납땜부의 引張强度에 關한 考察 : 脆性 땜 납재를 中心으로 focus on brittle material

裵原鎬 慶北工業專門大學 1980 論文集 Vol.17 No.-

In this study, the tensile strength of oblique plane brazed with brittle material were examined. The strength of obrique plane are theoreticaly analized by Maximumn Nomal Stress Theory and than compared with the experiment. The specimens were brazed BAg-4 and BCuP-3. The results of the analysis well coincide with the experiment as good enough to use all brittle brazing materials. They are as follows. 1. The simple tensile strength of the specimen with oblique angle ? is given ????????? 2. The base metal fractured with oblique angle ?????? 3. The strength of the oblique plane brazed with the brittle material increased with the growth of oblique angel.

有漢要素解析에 의한 應力擴大係數의 精度 改善에 關한 考察

裵原鎬 慶北工業專門大學 1981 論文集 Vol.18 No.-

In this paper, a study has been done to improve of accuracy value of the Stress Intensity Factors by the Finite Element Method. Especially to improve the Stress Intensity Factors value, we used a general program which is appropriatable to analyze the common elastic plastic stress and strain value. Every the stress Intencity factor of the Through Thickness crack, Single edge Noth, and Double edge notched plate is obtained by Stress Method, Displacement method-these are usual method of determination of the stress Intensity Factor by Finit Element method-and the special treat and compared with the Isida or Boie's theoretical value. The results were satisfactionable, the special method was usable to improve the Stress Intesity Factors values with the few elementes, moreover might use the existing program.

혼합모드 균열의 응력확대계수 해석과 정도 개선에 대한 고찰

배원호(Won-Ho Bae) 한국산업융합학회 2004 한국산업융합학회 논문집 Vol.7 No.4

The finite element method were used to determine the stress intensity factor of cracked plate. The stress method, displacement method and J Integral are most popular finte element method. ANSYS proposed another a kind of displacement method. In this paper, it was examined that the accuracy and utility of the ANSYS method could believable to determine the stress intensity factors of centered inclined crack. Generally, inclined crack has two portion of stress intensity factors, tensile mode F1 and shear mode F2. For the purpose of increasing the accuracy of stress intensity factors, examined the effect of the numbers of nodes and elements, crack tip element size and number of partition of the crack tip vicinity. It was found that the method proposed by ANSYS is useful and has high accuracy. Accuracy of calculated stress intensity factors was increased by increase of the number of nodes and elements, and at the small size of crack tip elements can get more highly accuracy.<br/> <br/>

SM45C강의 피로균열 진전 특성과 피로수명 예측

裵原鎬,金鎭烈 慶一大學校 1992 論文集 Vol.8 No.1

Generally, machine shaft which had defect or notch might be cracked by cyclic bending or torsion. The initiated crack at the small defect on the surface of shaft propagates to failure by cyclic load. Fatigue crack growth behavior of SM45C steel was investigated and the crack growth rate was expressed by stress intensity factor range, K. Fatigue life could predicted by the use of stress or strain at the notch tip, and is known that the strain method is more effective than stress method. To estimate the fatigue life, the linear rule was adopted, base line notch factor was used to estimate the strain at notch tip. It was assumed that stress concentration foctor Kt, and strain concentration factor Ke have the same value with the base line notch factor in plain strain condition like a small notch. The estimated fatigud life was compared with expelimental result, and the predicted life was well according with experiments. So that, it was found that the method by base line notch factor is useful to predicted fatigue life of small notched round bar.

人工 微小 缺陷이 있는 환봉의 피로균열 進展

裵原鎬 慶一大學校 1986 論文集 Vol.2 No.1

A round bar with small cracks or defects was studied under ratate-Bending Fatigue condition. The artificial defects were offered by drilled hole of diameter 0.3mm, depth 0.3mm. Fatigue initiation, for the small defect size or crack size, can be characterized by the fatigue limit range ?? , and threshold stress Intensity Factor range ?? , the functions of ?? . Also for the fatigue crack growth character of the meterial with small crack size can be expressed by the function of ?? and dℓ/dN functional of ?? . For the larger crack size from the defect, the fatigue crack growth formaly expressed ?? with adopting surface crack analize of plate bending. The fatigue crack growth rates of the defected zone decreasing rapidly in eary crack propagation stage, but the crack shape progress the surface crack type, rapidly increasing was found.

CRACK을 가진 長方形板의 應力擴大係數

裵原鎬 慶北工業專門大學 1983 論文集 Vol.20 No.-

Fracture of the materials or the Structure is Specified by Stress Intensity Factores. To find a profitable S.I.F in variable each case, The Lineal Stress Theory were used frequently. In this paper, The Boundary Collocation Method by Isida and some others is adopted to find the Stress Intensity Factores of the rectangular plate with central crack tip or inclind central crack tip. The result is satisfactionable, and this method is recommen able to find the Stress Intensity Factores of the rectangular plate with crack tip.

體積方法에 의한 應力擴大係數 解析 : 2次元 混合境界値 問題

裵原鎬 慶北工業專門大學 1984 論文集 Vol.21 No.-

Stress Intensity Factores bas been used as a parameter of Fracture or steress Concentration of structures or materials. The Body Force method also has been used a powerful method to evaluate the stress intensity factores, but mostly bas been used on the case of the stress boundary conditions were given. In this paper, The Body Force Method was studied in the case of the Boundary condition were given as stress and displacements. The complex stress functions used as a basic stress functions. The result of this study, this method is very useful for various complexed boundary value problem.