采用有限元法模拟了高速电弧喷涂枪二维气流场的分布.通过计算比较了收缩型和缩扩型喷管的流场差异,同时分析了不同的丝材夹角、丝交点离喷管出口距离等喷枪结构参数下喷枪气流场行为.结果显示,缩扩型喷管更有利于熔滴的雾化,丝交点离喷管出口距离减小至0、丝夹角为40°时更有利于熔滴的加速.基于以上模拟结果,优化设计了一种新型的高速电弧喷涂枪.喷涂粒子的形貌实验表明,新型喷枪的雾化粒子粒度比原始喷枪更细、分布更均匀.%In order to investigate fracture failure mechanism of asphalt mixture from micro-structure, probability method has been used to present a theoretical formula which develops to convert the aggregate weight gradation into the two-dimension (2D) quantity gradation. Two 2D digital specimens with different thicknesses of asphalt films are generated based on particle generation algorithm. Based on the discrete element method, the fracture process of asphalt mixture beam has been simulated and the effect of asphalt film thickness, cohesive strength of asphalt mastics and adhesive strength between asphalt mastic and aggregate on the fracture failure of asphalt mixture has been also investigated. The results show that the cracking has the tendency to occur in asphalt mastics for asphalt mixture with thick asphalt films and the cohesive strength of asphalt mastics has a great influence on fracture failure of this type mixture. For asphalt mixture with thin films, the early cracking often appears in asphalt mastics and propagation of cracking occurs at the interface between aggregates and mastics. Fracture initiation is dominated by the cohesive strength of asphalt mastics and propagation of cracking is controlled by adhesive strength between asphalt mastic and aggregate for mixture with thin films.
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