【摘要】 针对近场干涉导致轨头近表面的缺陷回波难以识别的问题，文章基于惠更斯积分建立钢轨内超声声场模型，结合数值计算与试验研究探头频率与晶片尺寸对声场分布及缺陷回波特征的影响。结果表明:晶片尺寸由10×10 mm增至20×20 mm时近场区长度由11.9 mm增至51.4 mm;频率由1 MHz增至4 MHz时近场区长度近似线性增加，而最大声压整体随频率与晶片尺寸增大而降低。近场区内缺陷回波与始波重叠显著，钢轨近表面的缺陷辨识困难；远场区内回波分离度提高，检测精度明显提升。更多还原

【Abstract】 To address the difficulty in identifying echoes from near-surface railhead defects caused by near-field interference, this paper establishes an ultrasonic sound-field model in rails based on the Huygens integral, and combines numerical simulations and experiments to investigate the effects of probe frequency and piezoelectric element size on the sound-field distribution and defect-echo features. The results show that, as the element size increases from 10×10 mm to 20×20 mm, the near-field length increases from 11.9 mm to 51.4 mm; as the frequency increases from 1 MHz to 4 MHz, the near-field length increases approximately linearly, while the peak sound pressure decreases overall with increasing frequency and element size. In the near field, defect echoes overlap significantly with the initial pulse, making near-surface railhead defects difficult to distinguish; in the far field, the echo separation improves and the detection accuracy increases markedly.更多还原