자동차 압연강의 X선 잔류응력과 피로수명비의 관계

김득진,박승용,김민철,조석수,주원식 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.1

The relation between fatigue damage of the specimen surface and X-ray residual stress in in-plane bending fatigue test was investigated for SPCC steel. The residual stress of SPCC steel before fatigue test was -270MPa. The residual stress σ_r consisted of three sequent stages except stress amplitude near fatigue limit. On the first stage compressive residual stress decreased rapidly. On the second stage gradually, and On the last stage slightly. σ_r-logN relationship showed linear behavior except the early part of fatigue life. The slope of σ_r-logN seemed to take a constant value regardless stress amplitude. On the other hand, the N_f line was able to be expressed by a straight line on the σ_r-logN plotting. Therefore, it was possible to propose a method estimating the fatigue life fraction N/N_f using the gradient of σ_r-logN and the N_f line.

Mercaptoglycerol 중 cis-alkenyl thioethers의 입체 특이적 합성

김득진,여영근 경북대학교 농업과학기술연구소 1987 慶北大農學誌 Vol.5 No.-

광학성체인 isopropylidene glycerols로 부터 mercaptogiycerol을 합성하였다. 1,2-Isopropylideneglycerol을 tosyl화 하고 다시 tosyl group을 thiolacetate로 치환하였다. 염기성 가수분해와 산화에 의해 1,1'-dithiobis-2,3-isopropylidene-2,3-propanediol이 생성되었다. 이 화합물을 mercaptogiycerol 합성을 위해 사용함으로써 1-decenyl lithium으로 cis-S-dec-1'-enyl-2,3-isopropylidene-1-mercapto-2,3-propanediol을 생성하였다. 본 생성물은 plasmalogenase용 thioplasmaloger 기질 조제에 사용된다. Methods were developed to synthesize optically active mercaptoglycerol from optically active isopropylidene glycerols. 1,2-Isopropylideneglycerol was tosylated and the tosyl group displaced with thiolacetate. Base hydrolysis and oxidation gave 1,1'-dithiobis-2,3-isopropylidene-2,3-propanediol. This compound could be used as a source of mercaptoglycerol, or reacted with 1-decenyl lithium to form cis-1-S-dec-1'enyl-2,3-isopropylidene-1-mercapto-2,3-propanediol. The latter is a stereospecific synthetic route to cis-alkenyl thioethers of protected mercaptoglycerol, and it may be useful for the preparation of a thioplasmalogen substrate for plasmalogenase.

빗속의 이사

김득진 샘터사 2012 월간 샘터 Vol.509 No.-

X-선 회절을 이용한 SS41불림재와 M.E.F.복합조직강의 ΔK 및 K_max 추정에 관한 연구

김득진,조용배,주원식,임만배 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.1

This study verified the relationship between fracture mechanics parameters(ΔK, K_max) and X-ray parameters(σ_r, B) for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. Residual stress, σ_r were independent on stress ratio(R=0.1, 0.5) by arrangement of ΔK and half-value breadth, B were independent by arrangement of K_max. The equation of σ_r-ΔK and B-K_max were established by the experimental datas. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

SS41불림재와 M.E.F.복합조직강의 X-선 잔류응력거동에 관한 연구

장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1

This study verified the relationship between fracture mechanics parameters ΔK, Kmax and X-ray residual stress σr for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). X-ray stress constant K was determined for the diffraction line of (211) plane using Cr-Kα radiation. K was -340.87 MPa/deg. The fatigue crack propagation test were carried out under stress ratios of 0.1 and 0.5 and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface Residual stress σr were independent on stress ratio (R=0.1, 0.5) by arrangement of ΔK. The equation of σr-ΔK was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

X선 반가폭을 이용한 자동차 압연강의 피로수명평가에 관한 연구

장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1

In order to predict the fatigue life using X-ray diffraction techniques, in-plane bending fatigue test was carried out for SPCC steel. The relation between fatigue damage on the specimen surface and half-value breadth of X-ray diffraction lines was investigated in the process of cyclic loading. The change of half-value breadth B consisted of the three sequent except stress amplitude near fatigue limit. On the first stage, half-value breadth B decreased rapidly, on the second stage slightly, and on the third stage rapidly. B/B0-logNf relationship showed linear behavior except the early part of life. The slople of the seemed to take constant value regardless stress amplitude. On the other hand, Nf line was able to be expressed by a straight line on the B/B0-logNf relationship. Therefore, it was possible to prepose a method estimating the fatigue life fraction N/Nf using the gradient of B/B0-logNf relationship and the N? line.

평면굽힘하중을 받는 표면미소균열의 프랙탈 특성에 관한 연구

장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1

Irregular shapes and growth behavior of surface nicro-crack showed very complex and nonlinear properties and many investigators have performed theoretical analyses and experiments on them to characterize fatigue strength. They had difficulties in estimating fatigue life due to random distribution, growth and coalescence of surface micro-cracks. The straightness of crack growth along intergranular and transgranular was prevented from irregular microstructure and precipitates. Euclid geometry can't quantify shape of surface micro-crack but fractal geometry can. Therefore, it is suggested that average fractal dimension of surface micro-cracks is able to estimate fatigue life but fractal dimension of maximum surface micro0crack is not in Al 2.24-T3 alloy.

X선 회절을 이용한 Al 2024-T3합금의 피로강도추정에 관한 연구

장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1

The fatigue process can be roughly divided into four stages ; cyclic hardening/softening, crack nucleation, crack propagation, and fracture. X-ray diffraction techniques can measure residual stress on the basis of the change of lattice plane spacings and half-value breadth corresponding to nonuiform strain in the constituent grains. The half-value breadth decreased with increase of number of cycles and stress range. The change of half-value breadth in crack nucleation is dependent on applied stress range. The relationship between propagation life ratio(N-Nc)/Nf and crack propagation half-value breadth ratio (Hw-Hwc)/Hwo shows strong linear behavior. Therefore, the remaining life of mechanical components can be predicted using half-value breadth ratio on crack nucleation and in process of crack propagation.

X선 프렉토그래피기법을 이용한 금속복합재료의 피로손상 해석에 관한 연구

김광영,박동성,박영철,윤두표,김득진 韓國非破壞檢査學會 1998 한국비파괴검사학회지 Vol.18 No.3

본 연구에서는 비파괴방법중 대단히 효과적인 방법이라 할 수 있는 X선 프렉토그래피 방법을 이용하여 파괴역학적 파라메타인 ΔK, Kmax의 정량적인 평가의 가능성에 대하여 검토하였다. 이를 위하여 Al2009-15v/o SiCw 복합재료와 SS41 불림재를 이용하여 피로균열진전시험을 실시하고 그 결과로부터 파면상의 X선 프렉토그래피 파라메타와 파면형성시의 파괴역학적 파라메타를 비교 ㆍ검토하여 X선 프렉토그래피에 의한 ΔKdhk Kmax의 평가 방법에 대하여 연구하였다. 또한, 정적하중부에 의한 소성변형률의 비파괴적 평가법에 대하여도 검토하였다. 이를 위하여 인장시험으로 소성변형을 부하한 후, X선 프렉토그래피 파라메타를 이용하여 부하된 소성변형량의 비파괴평가법에 대하여 검토하였다. 그 결과 피로파괴시의 부하된 Kmax와 피로손상 정도를 X선 프렉토그래피에 의하여 정량적으로 평가할 수 있는 방법을 제시하였다. It is attempted to verify the Quantitative relationship between fracture mechanical parameters(ΔK, Kmax)and X-ray parameters (residual stress, half-value breadth) of Al2009-15v/o SiCw composite, and normalized SS41 steel. In this study, fatigue crack propagation test were carried out X-ray diffraction was applied to fatigue fractured surface in order to investigate the change of residual stress and half-value breadth on fatigue fractured surface. And it is loaded prestrain to each tensile specimen, Al2009-15v/o SiCw composite(0.3,0.5,1,1.5,2%) and normalized SS41 steel(0.63,7.50,13.7,20%),for investigating plastic strain rate using nondestructive measurement method. X-ray diffraction was applied to the prestrained tensile specimens in order to measure the change of residual stress and half-value breadth.

SS41 강의 파손해석과 피로균열진전속도 추정에 관한 X-선적 연구

김득진,오세욱 東亞大學校 海洋資源硏究所 1994 硏究論文集 Vol.7 No.1

The failure analysis and estimation of fatigue crack propagation rate were carried out for SS41 steel normalized using X-ray diffraction technique. The half value breadth of diffraction profile and diffraction patterns by Laue camera were investigated on the surface of plastic deformed tension specimens according to degree of deformation. The residual strees was measured on the fatigue fractured surface. It is possible to estimate the plastic strain εp by the half value breadth B and diffraction patterns. The residual stress on the fatigue fractured surface tends to decrease with increasing ΔK and is larger when the stress ratio is higher. The relation between residual stress σr and effective stress intensity factor range ΔKeff can be expressed with following equation, σr = -75.2 log ΔKeff + 310.12. From this equation, estimation of fatigue crack propagation rate is possible by the residual stress.