共查询到15条相似文献,搜索用时 156 毫秒
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讨论了在役轧辊近表面缺陷的超声爬波检测技术,根据被检对象的特点确定爬波探头参数,结合应用实例对检测灵敏度、探头校准、爬波声束入射方向及缺陷回波波形进行了分析探讨,得出了可利用超声爬波对轧辊近表面进行缺陷检测及定位评定的结论。 相似文献
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基于超声表面波与爬波检测技术的特点,研究了二者在轧辊自动无损检测系统中的应用。提出了综合利用表面波与爬波对表面和近表面缺陷进行准确检测和精确定量的方法,并通过实例验证了该方法的有效性。 相似文献
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采用超声横波检测薄壁焊缝表面和近表面缺陷时存在检出率低的问题。分析了爬波的波型特征,制作了带长横孔和刻槽孔和刻槽缺陷的焊缝试块,对薄壁焊缝的爬波检测技术进行了试验研究。结果表明,采用特制的爬波探头检测时,灵敏度满足不同深度缺陷的检出要求,并且对表面和近表面缺陷表现出更好的检出能力。 相似文献
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超声爬波探头声场指向特性的试验研究 总被引:1,自引:0,他引:1
爬波检测是常规超声波检测的有力补充。由于爬波探头激发的声场具有多波型的特征,即在产生爬波的同时还会产生横波和头波,为全面了解爬波探头的声场特性,选用和制作了不同缺陷的对比试块进行测试。试验测得双晶片并列式爬波探头的声场指向特性图,获知该探头产生的爬波最大幅值方向与表面约呈15°,在33°左右激发的横波声压(4 mm横孔)比爬波主瓣高6dB,且该横波声压(大平底反射)比在30°左右激发的头波声压高9.5 dB。 相似文献
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This paper reports the development of a novel ultrasonic inspection technique that detects radial fatigue cracks on the far side of thin airframe stiffener ‘weep’ holes. These cracks are located on the upper part of the weep hole (12 o'clock position), away from the lower skin of the wing. Cracks in this position are not readily detectable by conventional ultrasonic inspection techniques, particularly for short cracks. A special technique using circumferential creeping waves was adapted to inspect for these cracks. The conventional creeping wave technique experiences a strong specular reflection from the near surface of the hole that masks the creeping wave signal that arrives later in time. In order to overcome this difficulty, a split-aperture (two-element) transducer was used that resulted in the specular and creeping wave echoes being approximately equal in magnitude. The two separate transducers allowed us to alternate between pulse-echo and pitch-catch modes of operation with a resulting improvement in detection sensitivity. In the case of 0.25-inch-diameter weep holes, optimum sensitivity was calculated to be around 5 MHz. The detection threshold was found to be approximately 0.003 inches and the signal saturated at crack lengths in excess of 0.020 inches. The original paint and surface finish had no substantial adverse effects on the technique's sensitivity. Similarly, changing the weep hole diameter or chamfer conditions did not significantly affect the technique's performance. These results were obtained using specimens with both machined notches and real fatigue cracks. 相似文献
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薄壁管材探伤用爬波探头的设计及应用 总被引:1,自引:0,他引:1
提出采用爬波检测薄壁管材横向缺陷的方案。设计了爬波探头的数学模型,根据该模型制作了双晶爬波探头。试验结果表明,爬波探头能检测出薄壁管材的内外壁上约0.07mm深的横向人工缺陷,尤其对表面缺陷具有较高的灵敏度。 相似文献
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