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쇼트피닝 가공에 의한 자동차용 Drive Plate의 내구성 향상
이국진,이동선,이재헌,정성균 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-
The effects of shot peening on the fatigue strength of SK-5M steel is investigated by experiment. The shot peening process is investigated optimum peening condition by changing impeller speed and exposure time. Bending fatigue test is accomplished to investigate the effect of optimum peening condition on the fatigue characteristics. As exposure time is increased, fatigue life in high stress is increased in early stage, become the maximum from 60 to 100 seconds, and then is decreased. Observing fracture surface through SEM after fatigue test, we can see clear configuration of cracks and peening layer.
3차원 대칭-셀 유한요소모델에 의한 다중 숏 충돌시 면적평균 피닝잔류응력해
김태형(Taehyung Kim),이형일(Hyungyil Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In this paper, we evaluate the peening residual stress due to multi-impacts via 3-D FE symmetry-cell model with combined physical and kinetic factors. With the FE model, we investigate FE peening coverage, dependency on the impact sequence, effect of repeated cycles. We obtain 4-node-averaged solution at four impact positions in the symmetry-cell, and compare the solution with XRD solution. In contrast to rigid and elastic shots, plastic shot produces residual stress closer to XRD solution. Generally XRD solution gives the area-averaged value at X-ray irradiated region. Considering this, we take FE area-averaged solution at all-nodes forming the cross-section at each depth of FE model with plastic shot. The area-averaged FE solution is much superior to 4-node-averaged in proximity to XRD solution. Consequently, we confirmed that the 3-D FE model can successfully evaluate the area-averaged peening residual stress by multi-impact.
쇼트피닝 가공에 의한 자동차용 Drive Plate의 내구성 향상
이국진(Kookjin Lee),이동선(Dongsun Lee),이재헌(Jaeheon Lee),정성균(Seongkyun Cheong) 한국생산제조학회 2005 한국생산제조시스템학회 학술발표대회 논문집 Vol.2005 No.5
The effects of shot peening on the fatigue strength of SK-5M steel is investigated by experiment. The shot peening process is investigated optimum peening condition by changing impeller speed and exposure time. Bending fatigue test is accomplished to investigate the effect of optimum peening condition on the fatigue characteristics. As exposure time is increased, fatigue life in high stress is increased in early stage, become the maximum from 60 to 100 seconds, and then is decreased. Observing fracture surface through SEM after fatigue test, we can see clear configuration of cracks and peening layer.
부식환경하에서 Al 7075-T6의 피로수명에 미치는 쇼트피닝의 효과에 관한 연구
정성균(Seong-Kyun Cheong),남지헌(Ji-Hun Nam),구대림(Dae-Lim Kou),노승남(Seung-Nam Ro) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.2
부식은 기계류나 금속 부품의 성능과 수명을 저해하는 가장 큰 요인으로 작용하고 있다. 이 논문에서는 쇼트피닝이 부식환경하에서 Al 7075-T6의 피로수명에 미치는 쇼트피닝의 효과를 연구하였다. 쇼트피닝한 시험편의 피로한도는 약 52% 증가하는 것으로 나타났으며, 금속재 부품의 피로수명을 크게 연장시키는 것으로 보인다. 쇼트피닝을 한 시험편과 쇼트피닝 하지 않은 시험편을 1주에서 1년까지 비교 시험한 결과 부식은 피로강도를 현격히 감소시켰다. 쇼트피닝을 하였을 경우에는 부식에 의해 6개월 까지는 피로강도 및 피로 수명이 감소하지 않은 것으로 나타났다. 따라서 쇼트피닝 가공이 금속재료의 수명에 대한 부식의 영향을 크게 감소시키는 효과가 있음을 알 수 있다. Corrosion highly affects the lifetime and performance of machinery metallic components. The effects of shot peening on the fatigue life of Al 7075-T6 under corrosive environment are investigated in this paper. Experimental results show that the fatigue limit of shot peened specimen increases about 52%. That means the fatigue life of metallic components is highly extended by shot peening. The corrosion greatly reduces the fatigue strength depending on the corrosive condition from one week up to one year. In case of shot peened specimen, the corrosion does not reduce the fatigue strength and fatigue life up to six months. It means that the shot peening has superior effectiveness to reduce the influence of corrosion to the metallic materials.
강용수(Yong-Soo Kang),박진성,오영택,김현규(Hyun-Kyu Kim),정성균(Seong-Kyun Cheong) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
To avoid inefficient shot peening process, the optimum shot peening condition should be investigated by experiments. In this paper, the optimum shot peening condition of SK-5M is detected and the changing of fatigue life is evaluated. Through a number of bending fatigue tests, the fatigue characteristics is investigated on different shot peening conditions. As exposure time and ball speed increase, the fatigue life increases in an early stage. The maximum fatigue life is obtained at the condition of 6 to 7 minutes of time and 50Hz of ball speed. From the experimental results, we can see that the over peening can reduce the fatigue life.
노승남,김희송,이승호 서울産業大學校 1998 논문집 Vol.47 No.1
Exhaust gas of vehicle is a big problem today. Reducing the weight of vehicle is desirable to reduce the cost and to improve the efficiency of vehicle. In the previous work, it seemed that the shot peening of suspension spring of vehicle improved the fatigue strength. Compressive residual stress can be obtained up to -792MPa by shot peening. Fatigue strength of machining spring steel is 425MPa. But fatigue strength of shot peened spring steel increased up to 756MPa.
소성숏이 포함된 3차원 다중충돌 대칭-셀 해석모델을 이용한 면적평균 피닝잔류응력해
김태형(Taehyung Kim),이형일(Hyungyil Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.4
In this paper, we estimate area-averaged solution of peening residual stress using a 3-D multi-impact symmetry-cell FE model. The symmetry-cell model includes factors reflecting peening phenomena and plastic shot. Area-averaged solution is much closer to XRD experimental solution than 4-node-averaged solution in plastic shot FE model. We then obtain FE Almen saturation curve corresponding to experimental Almen curve based on area-averaged solution. Using the curve, we obtain FE area-averaged solution in major peening materials, and compare the FE solution with experimental solution. In peening materials, surface, maximum compressive residual stress and deformation depth reach experimental solutions. Thus, FE Almen curve is useful for estimation of residual stress solution and could improve the efficiency of peening process. Consequently, it is confirmed that concept of area-averaged solution is the realistic analytical method for evaluation of peening residual stress.