• 대한기계학회논문집A
• /
• 제36권2호
• /
• pp.125-135
• /
• 2012

잔류응력 생성을 위한 대부분의 숏피닝 유한요소 해석모델은 숏볼이 재료표면에 수직으로 충돌하는 것을 가정한다. 하지만 실제 피닝공정에서 숏볼은 경사각을 갖고 재료표면에 충돌한다. 본 논문 에서는 잔류응력평가를 위한 3차원 경사충돌 유한요소 해석모델을 제안하였다. 다중경사충돌 유한요소 해석모델을 이용하여, 투사각, 충돌패턴, 숏볼수량 등 피닝인자들이 해석해에 미치는 영향을 조사하였다. 아울러 숏볼의 소성변형도 고려하였다. 유한요소해와 XRD 실험해의 비교를 통해 해석모델의 유효성을 검증했다. 본 논문에서 제안된 모델은 다양한 경사각에 대한 다중숏 충돌 유한요소 해석모델의 기초가될 것이다.

• 한국정밀공학회지
• /
• 제34권2호
• /
• pp.151-156
• /
• 2017

Shot peening is widely used to improve the fatigue life and strength of various mechanical parts and an accurate method is important for the prediction of the compressive residual stress caused by this process. A finite element (FE) model with an elliptical multi-shot is suggested for random-angled impacts. Solutions for compressive residual stress using this model and a normal random vertical-impact one with a spherical multi-shot are obtained and compared. The elliptical multi-shot experimental solution is closer to an X-ray diffraction (XRD) than the spherical one. The FE model's peening coverage also almost reaches the experimental one. The effectiveness of the model based on an elliptical shot ball is confirmed by these results and it can be used instead of previous FE models to evaluate the compressive residual stress produced on the surface of metal by shot peening in various industries.

• 대한기계학회논문집A
• /
• 제34권3호
• /
• pp.323-331
• /
• 2010

본 연구에서는 경사충돌시 피닝잔류응력 평가를 위해 3 차원 유한요소해석모델을 제안한다. 단일경사 충돌 해석모델을 이용해 Rayleigh 재료감쇠, 동적마찰 그리고 재료의 변형률 속도에 대한 영향을 알아 보고 이를 통합하여 피닝잔류응력 유일해를 얻는다. 숏볼은 변형을 고려한 소성숏을 포함한 해석 모델이며, 다중숏 경사충돌해석으로 확장한다. 다중경사충돌 해석모델은 단일경사충돌 연구를 통해 결정된 통합된 피닝인자들을 반영했고, 숏볼은 소성숏을 사용하였다. XRD 실험해와 비교시, 강체 및 탄성숏 해석모델에서 얻어진 해석해에 비해 소성숏 모델의 해석해가 실험해에 매우 근접하다. 이로부터 다양한 투사각을 갖는 3 차원 유한요소해석모델의 유효성을 확인하였다. 궁극적으로 제안된 해석모델은 실제 피닝현상을 충분히 반영하기 위한 다중숏 경사충돌해석연구의 초석이 될 것이다.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2005년도 춘계학술대회 논문집
• /
• pp.185-190
• /
• 2005

The shot peening process is often used to improve fatigue properties of metal parts. Among them, It is the most use in an auto-component. In order to achieve optimum, repeatable and reliable fatigue enhancement from the shot peening process, the important shot peening parameters must be controlled. In this paper, the optimum peening intensity (Almen intensity) condition is investigated by experiment. The Spur Gear steel was used to investigate shot peening effects. The fatigue life at $\sigma_a=1,050$ and $\sigma_a=1,250MPa$ first gently increases, then drops gently as peening intensity increases compared with unpeened specimen. Experimental results show that the optimum peening intensity range is $0.391\~0.434mmA$..So the fatigue strength and fatigue life have been tremendously increased by optimum-peening treatment. However, the fatigue strength and fatigue life have been decreased by over peeing.

• 한국기계기술학회지
• /
• 제20권6호
• /
• pp.844-851
• /
• 2018

In this study, the regression equation was suggested to predict of the shot ball velocity according to blade shapes based on discrete element (DE) analysis. First, the flat type blade DE model was used in the analysis, the validity of the DE model was verified by giving that the velocity of the shot ball almost equal to the theoretical one. Next, the DE analyses for curved and combined blade models was accomplished, and their analytical velocities of shot ball were compared with the theoretical one. The velocity of combined blade model was greatest. From this, the regression equation for velocity of shot ball according to the blade shape based on the DE analysis was derived. Additionally, the wind speed measurement experiment was carried out, and the experimental result and analytical one were the same. Ultimately, it was confirmed that the prediction method of the velocity of shot ball based on DE analysis was effective.