The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test,...The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test, differential scanning calorimetry （DSC） test and transmission electronic microscopy （TEM） observations. When pre-ageing temperature is 20℃ （natural ageing）, the peak hardness of subsequent artificial aged alloy is lower than that of T6 treated alloy （negative effect）, while a positive effect appears when pre-ageing temperature is above 80℃. The size of needlelike /3-precipitate in subsequent artificial aged alloy is much coarser when pre-ageing temperature is 20℃, which causes a decrease in peak-hardness. The positive effect occurs again when natural ageing time is longer than 3 weeks. There are seven exothermic peaks in DSC curve of as-quenched alloy, while the number and height of exothermic peak decrease with increasing pre-ageing temperature and natural ageing time.展开更多
针对钢管混凝土拱桥建设中预制拱肋预拼装验收遇到的问题,探讨一种结合三维激光扫描与建筑信息模型(Building Information Modeling,BIM)的虚拟验收方法。利用三维激光扫描技术获取预制拱肋的高精度实际点云模型并生成实际BIM模型,然后...针对钢管混凝土拱桥建设中预制拱肋预拼装验收遇到的问题,探讨一种结合三维激光扫描与建筑信息模型(Building Information Modeling,BIM)的虚拟验收方法。利用三维激光扫描技术获取预制拱肋的高精度实际点云模型并生成实际BIM模型,然后依据设计图纸建立预制拱肋的设计BIM模型并通过离散化处理生成设计点云模型,通过匹配BIM模型并进行布尔运算对预制拱肋外观进行初步验收,进一步用点云模型检测钢管直径尺寸、拱轴线并对点云模型进行精确配准计算模型间点云偏差,实现精确验收。结果表明:所测量预制拱肋方法符合相关规范要求,简化了验收流程,提高了验收结果的可靠性,并为类似结构的验收提供了参考。展开更多
基金supported by the National Key Technology R&D Program of China under grant No.2007BAE38B01
文摘The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test, differential scanning calorimetry （DSC） test and transmission electronic microscopy （TEM） observations. When pre-ageing temperature is 20℃ （natural ageing）, the peak hardness of subsequent artificial aged alloy is lower than that of T6 treated alloy （negative effect）, while a positive effect appears when pre-ageing temperature is above 80℃. The size of needlelike /3-precipitate in subsequent artificial aged alloy is much coarser when pre-ageing temperature is 20℃, which causes a decrease in peak-hardness. The positive effect occurs again when natural ageing time is longer than 3 weeks. There are seven exothermic peaks in DSC curve of as-quenched alloy, while the number and height of exothermic peak decrease with increasing pre-ageing temperature and natural ageing time.
文摘针对钢管混凝土拱桥建设中预制拱肋预拼装验收遇到的问题,探讨一种结合三维激光扫描与建筑信息模型(Building Information Modeling,BIM)的虚拟验收方法。利用三维激光扫描技术获取预制拱肋的高精度实际点云模型并生成实际BIM模型,然后依据设计图纸建立预制拱肋的设计BIM模型并通过离散化处理生成设计点云模型,通过匹配BIM模型并进行布尔运算对预制拱肋外观进行初步验收,进一步用点云模型检测钢管直径尺寸、拱轴线并对点云模型进行精确配准计算模型间点云偏差,实现精确验收。结果表明:所测量预制拱肋方法符合相关规范要求,简化了验收流程,提高了验收结果的可靠性,并为类似结构的验收提供了参考。
