쇼트블라스팅 공정 해석을 위한 충격하중에 따른 복합재료의 거동해석

송승엽(Seung Youp Song),박준영(Junyoung Park),김준식(Jun-Sik Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

A material surface treatment can be divided two parts, such as shot peening and shot blasting. shot peening is a method of using the residual compression stress in order to enhance the material surface. Many studies relevant to the shot peening have been conducted, for instance, the shape design of shot ball, the residual stress prediction, and the effect of material properties of the shot ball to the residual stress on the other hand, the shot blasting is a way of polishing the material surface, which is quite similar to the shot blasting, but its purpose is different. It has been also studied by many researchers. In this paper, the shot blasting process is simulated for layered steel structures to find out the optimal design parameters. The parametric study shows that it is possible to improve the process used to industry.

Study on the Influence of the Main Parameters of Pellets Distribution and Settlement in the Passage of Shot Blasting

Yanghou Chen,Yangbo Chen 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.4

The simulation of separation and settlement under two kinds of flue gas channels in the new dust removal method of shot peening is studied. By using FLUENT software and orthogonal experiment method of four factors and three levels, the influence of different velocity, pellet density, pellet size and velocity difference on the settlement rate of primary settlement channel is analyzed. The results show that the layout of flue gas channel has a significant impact on the mechanical settlement mode, which is mainly reflected in the impact of the density on the shot, and the shot density is the leading factor in several factors studied. Under the same flue structure, when the material density of the pellets is increased, the sedimentation rate of pellets can be increased, so the pellets are easier to be removed. In the process of free settlement, when the velocity of flue gas is increased, the migration path of pellets carried by flue gas increases, which is unfavorable to the removal of pellets. Therefore, the high density and inertia separation method is preferred in dust removal of shot blasting.

Fatigue Strength Improvement of Welded Joints of Existing Steel Bridges by Shot-Peening

Koji Kinoshita,Yuki Banno,Yuki Ono,Shohey Yamada,Mitsuru Handa 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2

Shot-peening recently can be applied to existing steel bridges due to the development of new vacuuming techniques of shots after peening in the construction site. This study experimentally investigates eff ects of fatigue strength improvement of shot-peening on welded joints. Bending fatigue tests using out-of-plane gusset welded joints specimens were carried out and three type specimens were compared: as-welded, grit-blasted, and shot-peened. In addition, this paper examines diff erences of fatigue strength improvement eff ects in case of applying shot-peening to inside of scallop where shots might be diffi cult to hit perpendicularly to weld toe of welded joints because of narrow space, and the residual stress measurement in order to clarify introducing compressive residual stress were carried out. As a result, it may be concluded that shot-peening can improve fatigue strength of welded joints and its mechanism was identifi ed as extension of crack initiation life and delay crack propagation due to benefi cial compressive residual stress in the vicinity of surface layer.

Effect of Ultrasonic and Air Blast Shot Peening on the Microstructural Evolution and Mechanical Properties of SUS304

유대황,J. L. Dong,D. H. Yoo,조인식,Y. Pyoun,I. Cho,신기삼 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.3

The effects of the process parameters of shot peening on the microstructural evolution and resulting mechanical property of SUS304 were investigated with microscopic analyses and mechanical tests. Shot peening on SUS304 was carried out with different impact energies and ball diameters (2.3 - 6 mm). In the deformed layer of 80 220 with a high dislocation density, the top layer of in thickness was found to have nanostructures of 20 100 nm with mechanical twins, which decreased with increasing depth. Deformation-induced martensite, whose volume fraction increased as the total energy deposition increased and/or as the ball diameter decreased, even at the same impact energy. The density of the multi-directional mechanical twins gradually decreased and single-directional mechanical twins gradually appeared instead. In addition, the average distance of twins increased with increasing depth in all of the shot-peened specimens. When processed by air blast shot peening, a few precipitates were additionally observed on the grain boundaries and are attributed to the conceivably higher temperature reached during the processing.

Performance enhancement of a doublepass solar air heater with a shot-blasted absorber plate and winglets

P. Ganesh Kumar,D. Sakthivadivel,K. Balaji,Mohammed Salman,Sung Chul Kim 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

A double-pass solar air heater (DPSAH) with shot blasting and winglets in the air passage is a recommended cost-effective design development to enhance thermal performance. Three different absorber plate configurations for DPSAHs were experimentally tested: (a) V-corrugation with shot blasting, (b) V-corrugation with shot blasting and a 4-3 winglet pattern, and (c) V-corrugation with shot blasting with a 3-2 winglet pattern. Furthermore, aluminum winglets were welded to the DPSAH absorber plate to increase the channel turbulence to enhance the heat transfer performance. The pressure drop and thermal performance of the DPSAHs with and without winglets were investigated using meteorological parameters such as ambient temperature, wind speed, solar irradiance, and interior temperature at regular time intervals. V-corrugation with 4-3 winglets has a maximum thermal efficiency and pressure drop of 49.5 % and 230 Pa, respectively, at a mass flow rate of 0.02 m/s. Results showed that the thermal efficiency of V-corrugation with 4-3 winglets was improved by a maximum of 7 % compared with the V-corrugation air heater. Finally, increasing the mass flow rate from 0.01 kg/s to 0.02 kg/s increases the pressure drop by 1.22 times for the V-corrugation and 1.3 times for the V-corrugation with 4-3 winglets. Furthermore, a complete economic study of DPSAHs for India is examined in this article.

유한요소해석을 이용한 스테인리스 스틸의 쇼트 블라스팅 공정 최적화

송승엽(Seung Youp Song),박준영(Junyoung Park),김준식(Jun-Sik Kim) 한국기계가공학회 2013 한국기계가공학회지 Vol.12 No.1

A shot blasting process is to improve the surface quality of stainless steels. The process is similar to a well-known shot peening that is used to strengthen the surface via the residual stress. In the shot blasting process, it is important to decide many parameters, such as the size, incident angle and velocity of shot balls, to effectively get rid of the iron oxide on the surface of stainless steels. In this study, the simulation of the shot blasting process is carried out by a finite element software, which can help to find out the optimal design parameters to cause the delamination of the iron oxide from the stainless steel substrate. The results obtained are also compared to those of the discrete element method to verify them.

SCM420H 유성기어의 쇼트피닝 효과에 관한 연구

류성기 ( Sung Ki Lyu ),안민주 ( Min Ju Ahn ),안인효 ( In Hyo Ahn ) 한국안전학회(구 한국산업안전학회) 2011 한국안전학회지 Vol.26 No.1

This study deals with the effect of the shot peening in SCM420H planetary gears. The hardness and roughness of the gear surface can be improved by shot blast and shot peening. there in, the shot peening techniques are welcomed especially as one of the physical surface improvement methods. The two treatments are used widely, because of the qualitative analysis of shot blast and shot peening has become possible and the surface treatment can be done with little costs compared with other surface improvement methods. Therefore, this study investigates the effects of shot blast and shot peening in surface shape. The fatigue strength test at a constant stress amplitude is performed by using an electrohydraulic serve-controlled pulsating tester. And fatigue test also explained characteristics of shot blast and shot peening of planetary gears.

다양한 표면처리가 Ti-6Al-4V 티타늄 합금의 피로강도 특성에 미치는 영향

김병수,부명환,-- 인제대학교 2002 仁濟論叢 Vol.17 No.1

Grit blasting is a standard method of inducing a roughened surface to promote physical attachment between porous coating and substrate material, but it has been shown to reduce fatigue strength. Shot peening is known to produce compressive residual surface stresses, which increase the fatigue strength of Ti-6Al-4V. However, these beneficial stresses can be reduced or eliminated under the influence of mechanical or thermal surface treatment. It is not known how subsequent grit blasting affects these benefits. In the present study, the effects of various pre-coating surface treatments, such as polished (control); belted and beaded; belted, beaded, and grit blasted; and belted, beaded, shot peened, and grit blasted, on the fatigue strength of Ti-6Al-4V were investigated. Belting and beading resulted in a slight increase in endurance limit (S<아래첨자>e</아래첨자>), but subsequent grit blasting reduced S<아래첨자>e</아래첨자> by over 15% from polished. Shot peening preceded grit blasting shows a fifty percent recovery over grit blasting alone in S<아래첨자>e</아래첨자>, suggesting that residual compressive surface stresses, induced by peening. were not eliminated by the blast process. R<아래첨자>α</아래첨자> and RMS measurements did not correlate with S<아래첨자>e</아래첨자> trends of Ti-6Al-4V. SEM results showed classical fatigue fractures, consistent with surface crack initiation.

Ti-6Al-4V 티타늄 합금의 표면처리가 피로특성에 미치는 영향

김병수(Byeong Soo Kim),부명환(Myung-Hwan Boo) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3

Grit blasting is a standard method of inducing a roughened surface to promote physical attachment between porous coating and substrate material, but it has been shown to reduce fatigue strength. Shot peening is known to produce compressive residual surface stresses, which increase the fatigue strength of Ti-6Al-4V. However, these beneficial stresses can be reduced or eliminated under the influence of mechanical or thermal surface treatment. It is not known how subsequent grit blasting affects these benefits. In the present study, the effects of various pre-coating surface treatments, such as polished (control); belted and beaded; belted, beaded, and grit blasted; and belted, beaded, shot peened, and grit blasted, on the fatigue strength of Ti-6Al-4V were investigated. Belting and beading resulted in a slight increase in endurance limit (S<SUB>e</SUB>), but subsequent grit blasting reduced S<SUB>e</SUB> by over 15% from polished. Shot peening preceded grit blasting shows a fifty percent recovery over grit blasting alone in S<SUB>e</SUB> suggesting that residual compressive surface stresses, induced by peening, were not eliminated by the blast process. R<SUB>a</SUB> and RMS measurements did not correlate with S<SUB>e</SUB> trends of Ti-6AI-4V. SEM results showed classical fatigue fractures, consistent with surface crack initiation.

Air Shot Blast 작업실 내부 환기 시스템 개선에 관한 수치해석

진도훈,Chin, Do-Hun 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.5

The purpose of this study is to design an effective atmospheric environment system through the design of the dust collection in the air shot room being operated in a domestic shipyard. The ventilation system in the current air shot room mostly uses a dust collecting filter to filter internal particles and releases them in the atmosphere. A conventional design was made too much. In order to prevent an error and draw an optimal design, Computational fluid dynamics (CFD) tried to be applied only to air shot room. In the advanced design technique, computer simulation was conducted to secure basic design data. In order to find the basic design of the ventilation system and the flow field in the air shot room at propeller mold workplace of a shipyard, the CFD was conducted. In the case of Model-1 as a conventional workplace, where air flows in the inlet due to the subatmospheric pressure generated by inhalation of an air blower and flows out to the outlet, a discharge flow rate was somewhat low, and there was the holdup zone in the room. In the case of Model-2 as an improved model, the ventilation system was improved in the Push-Pull type, and the holdup of the internal flow field was improved.