• 한국기계가공학회지
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• 제18권11호
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• pp.47-56
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• 2019

A deep neural network (DNN) model was proposed to predict the upset in the inertia friction welding process using a database comprising results from a series of FEM analyses. For the database, the upset length, upset beginning time, and upset completion time were extracted from the results of the FEM analyses obtained with various of axial pressure and initial rotational speed. A total of 35 training sets were constructed to train the proposed DNN with 4 hidden layers and 512 neurons in each layer, which can relate the input parameters to the welding results. The mean of the summation of squared error between the predicted results and the true results can be constrained to within 1.0e-4 after the training. Further, the network model was tested with another 10 sets of welding input parameters and results for comparison with FEM. The test showed that the relative error of DNN was within 2.8% for the prediction of upset. The results of DNN application revealed that the model could effectively provide welding results with respect to the exactness and cost for each combination of the welding input parameters.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.71-75
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• 1998

This study deals with the friction weldability of A7075-T6 having high specific strength. The friction welding conditions used are rotation speed 2000rpm, friction pressure 40MPa, friction time 1.5sec, upset pressure 40~100MPa, upset time 5sec. First, upset length was measured by displacement transducer. The plastic flow in 7075-T6 weld generates convex lens shaped resion by friction and concave lens shaped resion by axial force. Under the condition of upset pressure 85MPa, the friction welds have tensile strength of 552MPa and shear strength of 262MPa.

• Journal of Welding and Joining
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• 제20권3호
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• pp.98-104
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• 2002

A study on microstructures of welds for Zircaloy-4 sheath end closure by the resistance upset welding methods was carried out. Two upset welding process variations such as magnetic farce and multi-impulse resistance welding were used. Grain size and microhardness across welds were analysed in terms of welding parameters. Magnetic farce resistance weld with one cycle of unbalanced mode has smaller upset length and $\alpha-grain$ size in heat affected zone than those of multi-impulse resistance weld because of lower heat input and shorter welding time. Heat affected zone formed by two upset resistance welding variations revealed fine Widmanstatten structure or martensitic ${\alpha}'$ structure due to the high heating rate and foster cooling rate. Magnetic force resistance welds showed recrystallized grains before grain growth, whereas multi-impulse resistance welds showed full grain growth.

• 한국공작기계학회논문집
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• 제17권5호
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• pp.36-43
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• 2008

This research is tendencious to manufacture solid piston-rod of shock absorber as hollow piston-rod using friction welding. The SM45C has been welded to the SM45C-pipe in order to investigate the effect of upset pressure on friction weldability. The friction time and upset pressure was variable conditions under the conditions of spindle revolution of 2,000rpm, friction pressure of 55MPa, and upset time of 2.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied of friction weld, and so the results were as follows. When the upset pressure is sufficient, gets the high tensile strength. The optimal welding conditions were n=2,000rpm, $P_1$=55MPa, $P_2$=95MPa, $t_1$=1.5sec, $t_2$=2.0sec when the total upset length is 4.5mm.

• 한국항공우주학회지
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• 제45권9호
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• pp.724-733
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• 2017

비정상 비행(Upset) 상황으로 인한 항공기 사고는 유인항공기와 무인항공기 모두에 치명적인 피해를 발생시킨다. 본 논문은 항공기의 비정상 비행상황에 대한 실시간 대처와 추가적인 위험상황을 방지하기 위한 기법을 연구한다. 먼저 확장칼만필터(Extended Kalman Filter) 방법을 이용해 얻게 되는 예측값과 센서를 통해 실제로 얻게 되는 측정값 사이의 차이를 모니터링하여 현재 항공기의 비정상 비행 진입 여부를 판단한다. 또한, 확장칼만필터의 시간 업데이트를 반복 연산하여 얻은 수 초 후의 예측값을 통해 항공기의 상태가 비정상 비행상황으로 진입할 것인지를 예측하여 사전에 판단할 수 있게 된다. 본 연구결과는 차세대 유무인 항공기의 비정상 비행 상태 진입 방지 시스템 구축을 위한 가교 역할을 할 것으로 사료된다.

• 한국생산제조학회지
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• 제21권6호
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• pp.932-937
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• 2012

In the presented study, SM45C carbon steel parts were joined by friction welding. The welding process was carried out under optimized conditions using statistical approach. The study of SM45C is conducted with various combinations of process parameters. Parameter optimization, microstructure and mechanical property correlation are the major contribution of the study. The welded joints were produced by varying spindle revolution speed, friction pressure, upset pressure and burn-off length. Tension tests were applied to welded parts to obtain the strength of the joints. Fracturs properties were additionally obtained experimentally under fluctuated tensile loads. Microstructures using microphotographs were examined in the weld interface and weld region and heat affected zone and base metal and flash zone of welded parts. Finally, Hardness variations in welding zone and base metal were also obtained. Through these tests, the optimum conditions of parameters for ${\phi}20$ SM45C in friction welding were obtained when the friction spindle revolution was 1,950 rpm, the friction pressures was 30 MPs, upset pressures was 50 MPs.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.102-107
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• 2006

This study investigates the properties as the difference friction welding area on SM25C steel rod. The tensile and bending strength and of welded joints, the hardness distribution of welds, the microstructure of welds and the tensile fracture surfaces were mainly investigated through this experiment. The fixed friction welding conditions were revolution 2000rpm, friction pressure 70Mpa, friction time 1.5sec, upset pressure 100Mpa, upset time 2.0sec, upset length 2.8mm and changeable friction welding parameter was friction welding area.

• Journal of Welding and Joining
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• 제15권4호
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• pp.90-98
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• 1997

A copper-tungsten sintered alloy(Cu-W) has been friction welded to a tough pitch copper in order to investigate the effect of friction pressure on bonding strength and a charicteristic of fracture. The tensile strength of the friction welded joint was increased up to 90% of the Cu base metal under the condition of friction time 1.2 sec, friction pressure 4.5kgf/$\textrm{mm}^2$ and upset pressure 10kgf/$\textrm{mm}^2$. From the results of fracture surface analysis, the increase of friction pressure could remarkably decrease the force and the time to be normally acted on weld interface. The W particles which were included in the plastic zone of Cu side could induce fracture adjacent to the weld interface because their existance in Cu induces a decrease in available section area and an increase in notch effect. Therefore, the tensile strength was decreased at high friction pressure (6kgf/$\textrm{mm}^2$) because the destruction of W was increased by an increase in mechanical force and crack was formed at weld interface.

• 한국생산제조학회지
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• 제19권6호
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• pp.841-846
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• 2010

The present study examined the mechanical properties of the friction welding with hollow and solid shaft of SM45, of which the diameter is 25.2mm and 33mm. Friction welding was conducted at welding conditions of 2,000rpm, friction pressure of 50MPa, upset pressure of 70MPa, friction time of 0.4sec to 1.4sec by increasing 0.2sec, upset time of 2.0 sec including variable such as friction time are following. Under these conditions, a tensile test, a hardness test and a microstructure of weld interface were studied. The results were as follows : When the friction time was 1.0 seconds under the conditions, the maximum tensile strength of the friction weld happened to be 1,094MPa, which is 120% compared with the tensile strength of SM45C base metal. The upset length linearly increased as friction time increased. According to the hardness test, the hardness distribution of the weld interface was formed from 475Hv to 739Hv. HAZ(Heat Affected Zone) was formed from the weld interface to 2mm of SM45C.

• 한국공작기계학회논문집
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• 제10권2호
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• pp.73-78
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• 2001

In this study, the friction weldability and properties of inconel alloy(IN738LC) to stainless steel (STS304) was investigat-ed. Upset length increased according to increment of friction pressure and time. The tensile strength of the friction weld-ing reached 85% of the STS304 base metal strength under the conditions of 8 sec friction time, 50MPa friction pressure and 150 MPa upset pressure. From the result of fracture surface analysis, IN738LC section can be joined with STS 304 materials in shape of a convex lens. Also, the temperature of welded interface was measured with k-type thermocouple. Finally the plastic flow confirmed at the welded interface STS304 by micro test.