Joints between sintered silicon carbide （SSiC） were produced using a polysiloxane silicon resin YR3370 （GE Toshiba Silicones） as joining material. Samples were heat treated in a 99.99% nitrogen flux at temperature...Joints between sintered silicon carbide （SSiC） were produced using a polysiloxane silicon resin YR3370 （GE Toshiba Silicones） as joining material. Samples were heat treated in a 99.99% nitrogen flux at temperatures ranging from 1 100 ℃ to 1 300 ℃. Three point bending strength of the joint reached the maximum of 179 MPa as joined at 1 200℃. The joining layer is continuous, homogeneous and densified and has a thickness of 2 μm -5μm. The joining mechanism is that the amorphous silicon oxycarbide （SixOyCz） ceramic pyrolyzed from silicon resin YR3370 acts as an inorganic adhesive to SSiC substrate, which means the formation of the continuous Si-C bond structure between SixOyCz structure and SSiC substrate. Life prediction of the ceramic joint can be realized through the measurement of the critical time of the joint after the cyclic loading test.展开更多
The geometry of solder joint in SMT is one of the important factors whichdetermine the solder joint reliability. In this study, a type of solder joint specimen has beendesigned and is subjected to thermal cycling to f...The geometry of solder joint in SMT is one of the important factors whichdetermine the solder joint reliability. In this study, a type of solder joint specimen has beendesigned and is subjected to thermal cycling to failure between -55 ℃ to +125 ℃ with a 36℃/min heating and cooling rate and 10 min temperature holding times. The solder jointgeometry is castellated and controlled with different solder fillet shape and stand off height.A statistical analysis of the scattered thermal cycle lives of solder joints by two parameterWeibull's probability density function has been carried out in this paper. The experimentalresults show that the more reliable solder joint geometry has flat or slight convex solderfillet with a stand off height larger than 0.1 mm. The results may be the recommendedguideline to design optimal solder joint geometry.展开更多
Stress concentration has a significant effect on fatigue properties of welded butt joint of bogie.The influences of joint geometric parameters {weld edge transition arc radius r,weld toe inclination angle θ） on stre...Stress concentration has a significant effect on fatigue properties of welded butt joint of bogie.The influences of joint geometric parameters {weld edge transition arc radius r,weld toe inclination angle θ） on stress concentration coefficient Kt at weld toe and fatigue life N were studied based on the finite element software ABAQUS/FE-SAFE,and the parametric equations were founded based on regression analysis of Origin software.The results show that weld edge transition arc radius r plays the most important role in stress concentration coefficient Kt as well as weld toe inclination angle 0.For the same inclination angle θ,stress concentration coefficient Kt decreases gradually with transition arc radius r increasing.With inclination angle θ increases,the effect of transition arc radius r on stress concentration factor Kt is increasing continuously,also the effect of change in stress concentration coefficient Kt caused by r on fatigue life N is increasing continuously.While in the case of same weld edge transition arc radius r,stress concentration coefficient Kt increases with inclination angle θincreasing.With transition arc radius r increases,the effect of inclination angle θ on stress concentration factor Kt is decreasing constantly,the effect of change in stress concentration coefficient Kt caused by θ on fatigue life N is decreasing constantly.The associated parametric equations have important instructive significance for the improvement of stress concentration degree and fatigue life of welded butt joint for train bogie.展开更多
The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plas...The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plastic strain range of the solder joints were determined. Based on the calculated maximum plastic strain range the thermal fatigue life of the solder joints was calculated using Coffin-Manson equation. The influences of shape parameters including volume of solder joint, pad size and stand-off on the thermal fatigue life of the solder joints were also studied. The results show that the stress and strain distribution in the solder joint are not uniform; the interface between the lead and the solder joint is the high stress and strain region; the maximum stress and stain occur at the topmost point where the solder joint intersects with the inner side of the lead. The solder joint cracks should occur firstly at this point and propagate along the interface between the solder and the lead. The solder joint with the pad size of 1.25mm×0.35mm, the stand-off of 0.02mm and the solder volume of 0.026mm^3 has longer fatigue life than that of any others. These optimal parameters have been applied in practice to assemble the 240-pin, 0.5mm pitch QFP.展开更多
目的探究冰水冷疗在关节手术患者术后行关节锻炼镇痛中的有效性。方法选取钦州市第一人民医院行关节置换手术及关节镜手术的400例患者,随机数表法将其分为试验组和对照组,每组200例。2组进行关节锻炼后,对照组给予固体冰袋冷疗治疗;试...目的探究冰水冷疗在关节手术患者术后行关节锻炼镇痛中的有效性。方法选取钦州市第一人民医院行关节置换手术及关节镜手术的400例患者,随机数表法将其分为试验组和对照组,每组200例。2组进行关节锻炼后,对照组给予固体冰袋冷疗治疗;试验组行康玛士(Kindman)布冰袋冰水冷疗。比较2组患者术后疼痛程度[数字评分法(NPS)]、肿胀程度、关节活动度及并发症,并分析患者生活质量(SF-36量表)及对护理满意度。结果与对照组比较,试验组8、24、48 h NRS评分依次降低(P<0.05),且不同时间比较具有交互效应(P<0.05)。与对照组比较,试验组在8、24、48 h的肿胀程度降低效果更明显(P<0.05)。与对照组比较,试验组关节活动度优良率更高(P<0.05)。试验组并发症发生率低于对照组(P<0.05)。与对照组比较,试验组术后3、5 d SF-16评分均显著升高(P<0.05)。试验组护理满意度高于对照组(P<0.05)。结论康玛士布冰袋冰水冷疗在关节手术患者术后行关节锻炼中可明显降低患者疼痛程度,改善关节活动度,提高生活质量。展开更多
基金National Key Fundamental R&D Plan (2004CB217808)National Natural Science Foundation of China (20271037)
文摘Joints between sintered silicon carbide （SSiC） were produced using a polysiloxane silicon resin YR3370 （GE Toshiba Silicones） as joining material. Samples were heat treated in a 99.99% nitrogen flux at temperatures ranging from 1 100 ℃ to 1 300 ℃. Three point bending strength of the joint reached the maximum of 179 MPa as joined at 1 200℃. The joining layer is continuous, homogeneous and densified and has a thickness of 2 μm -5μm. The joining mechanism is that the amorphous silicon oxycarbide （SixOyCz） ceramic pyrolyzed from silicon resin YR3370 acts as an inorganic adhesive to SSiC substrate, which means the formation of the continuous Si-C bond structure between SixOyCz structure and SSiC substrate. Life prediction of the ceramic joint can be realized through the measurement of the critical time of the joint after the cyclic loading test.
文摘The geometry of solder joint in SMT is one of the important factors whichdetermine the solder joint reliability. In this study, a type of solder joint specimen has beendesigned and is subjected to thermal cycling to failure between -55 ℃ to +125 ℃ with a 36℃/min heating and cooling rate and 10 min temperature holding times. The solder jointgeometry is castellated and controlled with different solder fillet shape and stand off height.A statistical analysis of the scattered thermal cycle lives of solder joints by two parameterWeibull's probability density function has been carried out in this paper. The experimentalresults show that the more reliable solder joint geometry has flat or slight convex solderfillet with a stand off height larger than 0.1 mm. The results may be the recommendedguideline to design optimal solder joint geometry.
基金supported by the National Natural Science Foundation of China(No.51365014)Natural Science Foundation of Jiangxi Province(No.20151BAB206007)
文摘Stress concentration has a significant effect on fatigue properties of welded butt joint of bogie.The influences of joint geometric parameters {weld edge transition arc radius r,weld toe inclination angle θ） on stress concentration coefficient Kt at weld toe and fatigue life N were studied based on the finite element software ABAQUS/FE-SAFE,and the parametric equations were founded based on regression analysis of Origin software.The results show that weld edge transition arc radius r plays the most important role in stress concentration coefficient Kt as well as weld toe inclination angle 0.For the same inclination angle θ,stress concentration coefficient Kt decreases gradually with transition arc radius r increasing.With inclination angle θ increases,the effect of transition arc radius r on stress concentration factor Kt is increasing continuously,also the effect of change in stress concentration coefficient Kt caused by r on fatigue life N is increasing continuously.While in the case of same weld edge transition arc radius r,stress concentration coefficient Kt increases with inclination angle θincreasing.With transition arc radius r increases,the effect of inclination angle θ on stress concentration factor Kt is decreasing constantly,the effect of change in stress concentration coefficient Kt caused by θ on fatigue life N is decreasing constantly.The associated parametric equations have important instructive significance for the improvement of stress concentration degree and fatigue life of welded butt joint for train bogie.
基金Project(02336060) supported by the Natural Science Foundation of Guangxi Province , China
文摘The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plastic strain range of the solder joints were determined. Based on the calculated maximum plastic strain range the thermal fatigue life of the solder joints was calculated using Coffin-Manson equation. The influences of shape parameters including volume of solder joint, pad size and stand-off on the thermal fatigue life of the solder joints were also studied. The results show that the stress and strain distribution in the solder joint are not uniform; the interface between the lead and the solder joint is the high stress and strain region; the maximum stress and stain occur at the topmost point where the solder joint intersects with the inner side of the lead. The solder joint cracks should occur firstly at this point and propagate along the interface between the solder and the lead. The solder joint with the pad size of 1.25mm×0.35mm, the stand-off of 0.02mm and the solder volume of 0.026mm^3 has longer fatigue life than that of any others. These optimal parameters have been applied in practice to assemble the 240-pin, 0.5mm pitch QFP.
文摘目的探究冰水冷疗在关节手术患者术后行关节锻炼镇痛中的有效性。方法选取钦州市第一人民医院行关节置换手术及关节镜手术的400例患者,随机数表法将其分为试验组和对照组,每组200例。2组进行关节锻炼后,对照组给予固体冰袋冷疗治疗;试验组行康玛士(Kindman)布冰袋冰水冷疗。比较2组患者术后疼痛程度[数字评分法(NPS)]、肿胀程度、关节活动度及并发症,并分析患者生活质量(SF-36量表)及对护理满意度。结果与对照组比较,试验组8、24、48 h NRS评分依次降低(P<0.05),且不同时间比较具有交互效应(P<0.05)。与对照组比较,试验组在8、24、48 h的肿胀程度降低效果更明显(P<0.05)。与对照组比较,试验组关节活动度优良率更高(P<0.05)。试验组并发症发生率低于对照组(P<0.05)。与对照组比较,试验组术后3、5 d SF-16评分均显著升高(P<0.05)。试验组护理满意度高于对照组(P<0.05)。结论康玛士布冰袋冰水冷疗在关节手术患者术后行关节锻炼中可明显降低患者疼痛程度,改善关节活动度,提高生活质量。
