Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2(M2)melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites ...Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2(M2)melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM_6C_■ Cr_7C_3 and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV_(0.1)=865-960 of the laser fused structure of the alloy is due to the oc-currence of martensite.展开更多
爆炸活塞式高速开断装置的炸药腔室结构直接影响混合型限流熔断器的动力、电气性能,不合理的结构会使动子获得的动能降低,导致分断能力下降甚至分断失败。针对此问题,以LS-DYNA为仿真平台建立了非线性动力学模型,对炸药腔室的结构进行...爆炸活塞式高速开断装置的炸药腔室结构直接影响混合型限流熔断器的动力、电气性能,不合理的结构会使动子获得的动能降低,导致分断能力下降甚至分断失败。针对此问题,以LS-DYNA为仿真平台建立了非线性动力学模型,对炸药腔室的结构进行了研究,得到了冲击波在炸药腔室内的传播规律,并分别分析了炸药与活塞距离、活塞半径、药腔半径对开断性能的影响,结果表明炸药腔室结构参数存在最优值。最后设计了额定900 V/1 000 A的装置样机进行了分断特性和短路开断试验,试验中开断器动子位移与仿真一致,样机成功分断了预期峰值40 k A、电流上升率12 A/μs的短路电流,机械刚分时间为84μs,短路电流峰值被限制在22.7 k A,表明仿真模型与相关研究结论可用于指导爆炸活塞式高速开断器的结构优化设计。展开更多
The optical attenuation of fused silica glass impacted by high-speed micro-particle was studied.The high-speed impact test was carried out using a laser-driven flyer system which accelerated 16 ?m-thick flyer to high ...The optical attenuation of fused silica glass impacted by high-speed micro-particle was studied.The high-speed impact test was carried out using a laser-driven flyer system which accelerated 16 ?m-thick flyer to high speed of 3.7 km s?1.Scanning electron microscopy and optical microscopy were used to characterize the damage morphology of the impacted surface.The transmittance of the impacted glass samples was measured by means of UV/VIS double beam spectrophotometer.It was found that the transmittance of the impact region decreased due to the formation of structural defects such as crater,ejecta and micro-crack on the surface.A mathematic formula was established to explain the relationship between glass optical properties and the damaged modes,which aids to describe optical degradation and design long life optical equipments used in spacecrafts under space particles environment.展开更多
文摘Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2(M2)melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM_6C_■ Cr_7C_3 and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV_(0.1)=865-960 of the laser fused structure of the alloy is due to the oc-currence of martensite.
文摘爆炸活塞式高速开断装置的炸药腔室结构直接影响混合型限流熔断器的动力、电气性能,不合理的结构会使动子获得的动能降低,导致分断能力下降甚至分断失败。针对此问题,以LS-DYNA为仿真平台建立了非线性动力学模型,对炸药腔室的结构进行了研究,得到了冲击波在炸药腔室内的传播规律,并分别分析了炸药与活塞距离、活塞半径、药腔半径对开断性能的影响,结果表明炸药腔室结构参数存在最优值。最后设计了额定900 V/1 000 A的装置样机进行了分断特性和短路开断试验,试验中开断器动子位移与仿真一致,样机成功分断了预期峰值40 k A、电流上升率12 A/μs的短路电流,机械刚分时间为84μs,短路电流峰值被限制在22.7 k A,表明仿真模型与相关研究结论可用于指导爆炸活塞式高速开断器的结构优化设计。
基金supported by the National Natural Science Foundation of China (Grant No. 41274191)
文摘The optical attenuation of fused silica glass impacted by high-speed micro-particle was studied.The high-speed impact test was carried out using a laser-driven flyer system which accelerated 16 ?m-thick flyer to high speed of 3.7 km s?1.Scanning electron microscopy and optical microscopy were used to characterize the damage morphology of the impacted surface.The transmittance of the impacted glass samples was measured by means of UV/VIS double beam spectrophotometer.It was found that the transmittance of the impact region decreased due to the formation of structural defects such as crater,ejecta and micro-crack on the surface.A mathematic formula was established to explain the relationship between glass optical properties and the damaged modes,which aids to describe optical degradation and design long life optical equipments used in spacecrafts under space particles environment.
