为了获取能更准确评价BRA改性沥青高温性能的指标,对BRA掺量不同的改性沥青进行了软化点试验、旋转黏度试验、常规震荡剪切试验(DSR)、多应力蠕变恢复(MSCR)等试验,比较分析试验得到的BRA改性沥青的软化点、当量软化点T 800、旋转黏度...为了获取能更准确评价BRA改性沥青高温性能的指标,对BRA掺量不同的改性沥青进行了软化点试验、旋转黏度试验、常规震荡剪切试验(DSR)、多应力蠕变恢复(MSCR)等试验,比较分析试验得到的BRA改性沥青的软化点、当量软化点T 800、旋转黏度、车辙因子G^*/sinδ,Shenoy不可恢复柔量、J nr平均不可恢复蠕变柔量评价指标的异同,并将这些指标分别与BRA改性沥青混合料60℃动稳定度进行回归分析.结果表明,BRA掺量与沥青软化点、当量软化点均存在良好的线性函数关系,而与135℃旋转黏度、车辙因子、Shenoy不可恢复柔量、J nr 0.1,J nr 3.2均存在良好的指数函数关系;BRA改性沥青的高温性能越好,其沥青混合料的动稳定度对BRA改性沥青高温性能的变化越敏感;J nr 0.1,J nr 3.2,Shenoy不可恢复柔量、当量软化点、软化点在BRA改性沥青高温性能的评价上均优于车辙因子,而135℃旋转黏度与BRA改性沥青混合料动稳定度的相关性最差;建议采用J nr值、Shenoy不可恢复柔量作为BRA改性沥青高温性能的评价指标,在没有条件情况下,也可以采用当量软化点作为BRA改性沥青高温性能的评价指标.展开更多
In order to obtain a high-quality weld during the laser welding process, extracting the characteristic parameters of weld pool is an important issue for automated welding. In this paper, the type 304 austenitic stainl...In order to obtain a high-quality weld during the laser welding process, extracting the characteristic parameters of weld pool is an important issue for automated welding. In this paper, the type 304 austenitic stainless steel is welded by a 5 kW high-power fiber laser and a high-speed camera is employed to capture the topside images of weld pools. Then we propose a robust visual-detection approach for the molten pool based on the supervised descent method. It provides an elegant framework for representing the outline of a weld pool and is especially efficient for weld pool detection in the presence of strong uncertainties and disturbances. Finally, welding experimental results verified that the proposed approach can extract the weld pool boundary accurately, which will lay a solid foundation for controlling the weld quality of fiber laser welding process.展开更多
文摘为了获取能更准确评价BRA改性沥青高温性能的指标,对BRA掺量不同的改性沥青进行了软化点试验、旋转黏度试验、常规震荡剪切试验(DSR)、多应力蠕变恢复(MSCR)等试验,比较分析试验得到的BRA改性沥青的软化点、当量软化点T 800、旋转黏度、车辙因子G^*/sinδ,Shenoy不可恢复柔量、J nr平均不可恢复蠕变柔量评价指标的异同,并将这些指标分别与BRA改性沥青混合料60℃动稳定度进行回归分析.结果表明,BRA掺量与沥青软化点、当量软化点均存在良好的线性函数关系,而与135℃旋转黏度、车辙因子、Shenoy不可恢复柔量、J nr 0.1,J nr 3.2均存在良好的指数函数关系;BRA改性沥青的高温性能越好,其沥青混合料的动稳定度对BRA改性沥青高温性能的变化越敏感;J nr 0.1,J nr 3.2,Shenoy不可恢复柔量、当量软化点、软化点在BRA改性沥青高温性能的评价上均优于车辙因子,而135℃旋转黏度与BRA改性沥青混合料动稳定度的相关性最差;建议采用J nr值、Shenoy不可恢复柔量作为BRA改性沥青高温性能的评价指标,在没有条件情况下,也可以采用当量软化点作为BRA改性沥青高温性能的评价指标.
基金Project was supported by the National Key R&D Program of China(Grant No.2017YFB1104404)
文摘In order to obtain a high-quality weld during the laser welding process, extracting the characteristic parameters of weld pool is an important issue for automated welding. In this paper, the type 304 austenitic stainless steel is welded by a 5 kW high-power fiber laser and a high-speed camera is employed to capture the topside images of weld pools. Then we propose a robust visual-detection approach for the molten pool based on the supervised descent method. It provides an elegant framework for representing the outline of a weld pool and is especially efficient for weld pool detection in the presence of strong uncertainties and disturbances. Finally, welding experimental results verified that the proposed approach can extract the weld pool boundary accurately, which will lay a solid foundation for controlling the weld quality of fiber laser welding process.
