To enhance the application of ultrasonic waves to rail flaw detection and train safety monitoring, a finite model was introduced to study the ultrasonic sound field distribution characters. In this model, the acoustic field due to ultrasonic propagating in rail was simulated with different frequencies and sizes of ultrasonic sources. The distribution of acoustic pressure on central axis was plotted; and the relationships between ultrasonic near field length, spread angle, frequency, and source size were discussed. The results show that among the models with the same source size, the one with a frequency of 1.0 MHz has the longest near-field length and the best spread angle; and among the models with the same ultrasonic frequency, the one with a source size of 40 mm has the longest near-field length and the best spread angle.%为进一步研究超声波的声场分布特性,增强超声波在高速铁路中轮轨探伤、列车安全监测等方面的应用,设计了轮轨有限元模型,模拟了不同声源尺寸下不同频率超声波在轮轨材料中传播时的声场分布,绘制了声源轴线上的声压分布曲线,在此基础上,分析了超声波近场长度、指向性、超声波频率及声源大小之间的关系.研究结果表明:在相同声源直径的模型中,频率为1.0 MHz的超声波近场长度最长,指向性最好;相同超声频率的模型中,声源直径为40mm的超声波近场长度最长,指向性最好.
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