Hole Drilling 방법의 열과 표면처리에 의한 잔류응력 계산

유재석,박세만 明知大學校 産業技術硏究所 2008 産業技術硏究所論文集 Vol.27 No.-

Residual stresses deteriorate strength of materials adversely affecting quality of industrial products. A removable or a reduction of the residual stresses is an essential procedure in successful product developments. Effective and convenient methods are necessary for detection and evaluation of the residual stresses. In this investigation Hole Drilling Method is chosen for identification and a quantitative determination of the residual stresses of specimen in different groups under three heat and surface treatment conditions. The specimen in the first group is standard reference specimen without the heat treatment. The ones in the second group is carburized specimen with the surface treatment. In another group specimen is exposed to high frequency electric power to achieve the desired heat treatment condition. The residual stresses of metal alloys are evaluated subsequently with an analysis for the specimens prepared under a variety of heat and surface conditions, revealing complex effects of the treatments on the residual stresses as well as on properties of the materials. The amount of the residual stresses comes in that order of the specimen with the high frequency, with the carburized treatment and the specimen without the heat treatment. The quantitative analysis as well as experience suggests reliable and effective processes to eliminate or reduce the residual stresses. Also, during process of pipe welding a high level of residual stresses is observed to develop and its level increases non-uniformly with a depth into a hole. Based on the experimental results and the analysis, proper treatment conditions can be predicted to reduce or even completely eliminate the residual stresses, leading to an establishment of reliable methods for a control of the residual stresses.

Features of Mechanical Properties and Residual Stress Distribution in Butt Joint of HSB690-SM355 Dissimilar Steel

엄태환,장경호,이재익,Sazid Nizam Khan,Hirohata Mikihito 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.3

HSB690 steel is high-performance steel for bridges manufactured by POSCO of Korea through a thermo-mechanical controlled process (TMCP). However, the application of these high-performance steels to the entire structure is challenging in terms of cost. The combination of dissimilar steels can be a good alternative. Welding of HSB690 steel is mainly used for joining dissimilar steel materials. Residual stresses and deformations caused by welding aff ect the fatigue performance of the structure. In particular, tensile residual stress around welds signifi cantly aff ects the fatigue and fracture behavior of dissimilar materials by increasing the mean stress. Bridge structures using HSB690 are gradually increasing, but the features of residual stress at the similar or dissimilar welded joint using HSB690 have not been reported. The physical and mechanical properties at each temperature are essential for residual stress analysis. However, the mechanical properties of HSB690 with temperature are not clear yet. Thus, before the residual stress analysis, the mechanical properties of HSB690 were determined by high-temperature tensile tests. Then, the three-dimensional (3D) thermal elastic–plastic fi nite element (FE) analysis was conducted to assess the residual stresses in the butt-welded member composed of SM355 and HSB690 steel. The residual stresses measured by the strain release method were compared for the precision of the analysis results. Moreover, residual stress analysis in welds composed of the same kind of steel materials was also performed for comparison. As a result of simulations and experimental measurements, in the member welded with dissimilar steels, the SM355 side showed almost similar residual stress distribution compared to corresponding similar steel welds, but the residual stress distribution in the HSB690 side was higher than that of the similar steel welds.

The effect of initial stress induced during the steel manufacturing process on the welding residual stress in multi-pass butt welding

Park, Jeong-ung,An, Gyubaek,Woo, Wanchuck The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

A residual stress generated in the steel structure is broadly categorized into initial residual stress during manufacturing steel material, welding residual stress caused by welding, and heat treatment residual stress by heat treatment. Initial residual stresses induced during the manufacturing process is combined with welding residual stress or heat treatment residual stress, and remained as a final residual stress. Because such final residual stress affects the safety and strength of the structure, it is of utmost importance to measure or predict the magnitude of residual stress, and to apply this point on the design of the structure. In this study, the initial residual stress of steel structures having thicknesses of 25 mm and 70 mm during manufacturing was measured in order to investigate initial residual stress (hereinafter, referred to as initial stress). In addition, thermal elastic plastic FEM analysis was performed with this initial condition, and the effect of initial stress on the welding residual stress was investigated. Further, the reliability of the FE analysis result, considering the initial stress and welding residual stress for the steel structures having two thicknesses, was validated by comparing it with the measured results. In the vicinity of the weld joint, the initial stress is released and finally controlled by the weld residual stress. On the other hand, the farther away from the weld joint, the greater the influence of the initial stress. The range in which the initial stress affects the weld residual stress was not changed by the initial stress. However, in the region where the initial stress occurs in the compressive stress, the magnitude of the weld residual compressive stress varies with the compression or tension of the initial stress. The effect of initial stress on the maximum compression residual stress was far larger when initial stress was considered in case of a thickness of 25 mm with a value of 180 MPa, while in case of thickness at 70 mm, it was 200 MPa. The increase in compressive residual stress is almost the same as the initial stress. However, if initial stress was tensile, there was no significant change in the maximum compression residual stress.

Correlation of localized residual stresses with ductile fracture toughness using in situ neutron diffraction and finite element modelling

Wang, Huai,Woo, Wanchuck,Lee, Soo Yeol,An, Gyubaek,Kim, Dong-Kyu Elsevier 2019 International journal of mechanical sciences Vol.160 No.-

<P><B>Abstract</B></P> <P>Localized residual stresses were correlated to ductile fracture toughness quantitatively in steel and aluminium alloys using in situ neutron diffraction method coupled with elastic-plastic finite element modelling. Local out-of-plane compression (LOPC) method generated compressive and tensile residual stresses in the vicinity of the fatigue pre-crack front in two compact tension (CT) specimens, respectively, and the evolution of the stress fields was simultaneously measured using in situ neutron diffraction technique under mode-I fracture loading. The results clearly showed that the localized tensile residual stress apparently accelerated stress transfer at the mid-thickness of the CT specimen compared to the specimen having compressive residual stress. The coupled quasi-static ductile fracture simulations and neutron diffraction results revealed a clear correspondence of fracture initiation toughness with localized residual stresses in both steel and aluminium alloys. In the aluminium case, tensile residual stress of 208 MPa was obviously detrimental to the fracture toughness resulting in a 43% reduction while compression of −220 MPa increases by up to 14%. On the other hand, localized residual stress in steel hardly affected fracture initiation toughness due to high plastic dissipation energy. This experiment-simulation coupled study quantitatively elucidates the distinctive role of plastic deformation and stress triaxiality in ductile fracture initiation between steel and aluminium alloy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spatially-resolved stress/strain mapping is done inside the material under loading. </LI> <LI> Ductile fracture initiation reveals a clear correlation to localized residual stresses. </LI> <LI> Accumulation of plastic deformation dominates fracture of the EH40 steel. </LI> <LI> Increase of stress triaxiality governs fracture of the Al5083 aluminium. </LI> <LI> Tensile residual stresses reduce 43% of fracture toughness of the Al5083 aluminium. </LI> </UL> </P>

The effect of initial stress induced during the steel manufacturing process on the welding residual stress in multi-pass butt welding

Jeong-ung Park,Gyubaek An,Wanchuck Woo 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

A residual stress generated in the steel structure is broadly categorized into initial residual stress during manufacturing steel material, welding residual stress caused by welding, and heat treatment residual stress by heat treatment. Initial residual stresses induced during the manufacturing process is combined with welding residual stress or heat treatment residual stress, and remained as a final residual stress. Because such final residual stress affects the safety and strength of the structure, it is of utmost importance to measure or predict the magnitude of residual stress, and to apply this point on the design of the structure. In this study, the initial residual stress of steel structures having thicknesses of 25 mm and 70 mm during manufacturing was measured in order to investigate initial residual stress (hereinafter, referred to as initial stress). In addition, thermal elastic plastic FEM analysis was performed with this initial condition, and the effect of initial stress on the welding residual stress was investigated. Further, the reliability of the FE analysis result, considering the initial stress and welding residual stress for the steel structures having two thicknesses, was validated by comparing it with the measured results. In the vicinity of the weld joint, the initial stress is released and finally controlled by the weld residual stress. On the other hand, the farther away from the weld joint, the greater the influence of the initial stress. The range in which the initial stress affects the weld residual stress was not changed by the initial stress. However, in the region where the initial stress occurs in the compressive stress, the magnitude of the weld residual compressive stress varies with the compression or tension of the initial stress. The effect of initial stress on the maximum compression residual stress was far larger when initial stress was considered in case of a thickness of 25 mm with a value of 180 MPa, while in case of thickness at 70 mm, it was 200 MPa. The increase in compressive residual stress is almost the same as the initial stress. However, if initial stress was tensile, there was no significant change in the maximum compression residual stress.

Neutron diffraction residual stress analysis during fatigue crack growth retardation of stainless steel

Seo, Sukho,Huang, E-Wen,Woo, Wanchuck,Lee, Soo Yeol Elsevier 2017 International journal of fatigue Vol.104 No.-

<P><B>Abstract</B></P> <P>After tensile overloading during fatigue crack growth, retardation of the crack growth rate was significant. Neutron diffraction was employed to examine the evolution of crack-tip residual stress fields during constant-amplitude cyclic loading and during fatigue crack growth following the overload. It was found that the tensile overload induces larger compressive residual stress and zone size near the crack tip in the crack-growth and crack-opening direction. For the maximum crack growth retardation, the largest compressive residual stresses were measured in the region between an overloading point and the current propagating crack tip, for all three of the orthogonal directions. Such large compressive residual stresses in the crack-wake region are thought to reduce the crack tip driving force, thereby retarding the crack propagation rate significantly. Residual stress mapping was performed to examine the effect of the fatigue stress state on the residual stresses in the three different regions from the centerline to the surface, along the through-thickness direction in the compact-tension specimen. Much larger compressive residual stresses were measured at the surface than at mid-thickness. It is thought that larger compressive residual stresses at the surface result from the plane stress condition, resulting in a slower fatigue crack growth rate at the surface of the specimen.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Neutron diffraction was used to measure residual stress fields near the crack tip. </LI> <LI> A tensile overload induced larger compressive residual stress and zone size. </LI> <LI> The maximum retardation revealed the largest compressive residual stresses. </LI> <LI> Compressive residual stresses were larger at the surface than in the middle. </LI> <LI> Effect of the fatigue stress state on the residual stress was revealed. </LI> </UL> </P>

Design optimization of precision casting for residual stress reduction

Keste, Appasaheb Adappa,Gawanden, Shravan Haribhau,Sarkar, Chandrani Society for Computational Design and Engineering 2016 Journal of computational design and engineering Vol.3 No.2

Normally all manufacturing and fabrication processes introduce residual stresses in a component. These stresses exist even after all service or external loads have been removed. Residual stresses have been studied elaborately in the past and even in depth research have been done to determine their magnitude and distribution during different manufacturing processes. But very few works have dealt with the study of residual stresses formation during the casting process. Even though these stresses are less in magnitude, they still result in crack formation and subsequent failure in later phases of the component usage. In this work, the residual stresses developed in a shifter during casting process are first determined by finite element analysis using ANSYS(R) Mechanical APDL, Release 12.0 software. Initially the analysis was done on a simple block to determine the optimum element size and boundary conditions. With these values, the actual shifter component was analyzed. All these simulations are done in an uncoupled thermal and structural environment. The results showed the areas of maximum residual stress. This was followed by the geometrical optimization of the cast part for minimum residual stresses. The resulting shape gave lesser and more evenly distributed residual stresses. Crack compliance method was used to experimentally determine the residual stresses in the modified cast part. The results obtained from the measurements are verified by finite element analysis findings.

링 전단시험기를 이용한 암석절리의 잔류강도 특성에 관한 연구

권준욱,김선명,윤지선 한국지반공학회 2000 한국지반공학회논문집 Vol.16 No.6

Residual stress is defined as a minimum stress with a large displacement of specimens and the residual stress after peak shear stress appears with displacement volume but there is no provision to select the residual stress. In the previous study, residual stress was recorded when the change of shear load is small in the condition of the strain more than 15%. But, in this study, hyperbolic function((No Abstract.see full/text), b=experimental constant) of soil test is adapted to joint of rock and the propriety is investigated. In a landslide and landsliding of artificial slope, wedge failure of tunnel with a large displacement, tests are simulated from peak stress to residual stress for safety analysis. But now. direct shear stress and triaxial compressive tests are usually performed to find out characteristics of shear stress about joint. Although these tests get a small displacement, that data of peak stress and residual stress are used for safety analysis. In this study, we tried to determine failure criteria for joints of rock using ring shear test machine. The residual stress following shear behavior was determined by the result of ring shear test and direct shear test. In conclusion, after comparing the results of the two test, we found that cohesion(c) and internal friction angle(ø) of ring shear test are 30% and 22% respectively of those of the direct shear test.

5083-0 Al합금 鎔接材의 잔류응력에 관한 硏究

권관구(Gwan-Gu Gwon) 산업기술교육훈련학회 2012 산업기술연구논문지 (JITR) Vol.17 No.4

The purpose of this thesis was to investigate the welding characteristics and the residual stress behavior of SS41, commonly using power station, aircraft and ship. The experimented material was GMA welded in order to look over the residual stress distribution was measured under perfect restraint and nonrestraint welding conditions. From these test, we reached conclusion as followings ; The welding residual stress welded specimens was much higher in restraint condition than in nonrestraint. In case of restraint welding, the σx direction residual stress was measured the tensile residual stress. In case of nonrestraint welding, it was rapidly changed to compressive residual stress at about 15mm from welding bead center. In case of nonrestraint welding, the σy direction residual stress was measured the tensile residual stress. In case of restraint welding, it was changed to compressive residual stress at 40~45mm from welding bead center.

Effect of heat treatment residual stress on stress behavior of constant stress beam

Kwak, Si Young,Hwang, Ho Young Society for Computational Design and Engineering 2018 Journal of computational design and engineering Vol.5 No.1

Although most casting and heat treatment processes generate significantly high residual stress in the products, this factor is generally not taken into account in the design stage of the product. In this study, experimental study and numerical analysis were conducted on a constant stress beam to examine effects of the residual stress generated during the heat treatment process on yielding behavior of the product in use. A constant stress beam of SUS 304 was designed in order to test the stress behavior related to residual stress. The residual stresses generated during quenching heat treatment of the beam were measured in advance by ESPI (Electronic Speckle-Pattern Interferometry) equipment, and then the external stresses generated while applying a simple external load on the beam were measured. Also, the residual stress distribution generated during the heat treatment process was computed using a numerical analysis program designed for analyzing heat treatment processes. Then, the stress distribution by a simple external load to the beam was combined with the calculated residual stress results of the previous heat treatment step. Finally, the results were compared with experimental ones. Simulation results were in good agreement with the experimental results. Consistency between experimental results and computational results prove that residual stress has significant effects on the stress behavior of mechanical parts. Therefore, the residual stress generated in the previous heat treatment step of casting must be taken into account in the stage of mechanical product design.