Near-surface defect detection in additively manufactured components using laser induced phased arrays with surface acoustic wave crosstalk suppression
Near-surface defect detection in additively manufactured components using laser induced phased arrays with surface acoustic wave crosstalk suppression
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DOI：
10.1016/j.matdes.2023.112453
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发表时间：
2023-11
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通讯作者：
Geo Davis;T. Stratoudaki;Peter Lukacs;Matthew W. Riding;Ahmed Al Fuwaires;Panagiotis Kamintzis;Don Pieris;Alan Keenan;Paul D. Wilcox;Gareth Pierce;Charles MacLeod;Stewart Williams
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作者：
Geo Davis;T. Stratoudaki;Peter Lukacs;Matthew W. Riding;Ahmed Al Fuwaires;Panagiotis Kamintzis;Don Pieris;Alan Keenan;Paul D. Wilcox;Gareth Pierce;Charles MacLeod;Stewart Williams
增材制造工艺的过程中检测需要一种技术，该技术可以在极端操作环境、小尺寸缺陷以及由随后沉积的层引起的材料的循环熔化和加热的情况下提供可靠的测量。远程和耦合剂的超声波检测技术，使用体波，可以成像近表面的缺陷，可以解决这些过程中的检查要求。激光诱导相控阵（利帕）是基于激光超声原理产生和检测超声，而阵列是在后处理中合成的。然而，当使用LIPA进行检测时，表面声波（SAW）干扰体波模式，从而引起串扰和伪影，这使得近表面缺陷成像困难。这项工作实验验证和比较SAW抑制的五种技术：幅度阈值，平均波形减法，主成分减法，频率波数滤波，相位相干成像。基于在Ti-6Al-4V定向能量沉积弧（DED-Arc/Ti6 Al 4V）样本上合成的71个元素利帕数据，在横向波的超声图像中证明了SAW抑制，该样本具有直径为1.1 mm的侧钻孔，位于被检表面下方1.4 mm处。报告的结果表明，主成分减法的方法实现了最高的“信号串扰比”的16分贝的改善，同时成功地抑制了SAW。
In-process inspection of the additive manufacturing process requires a technique that can provide reliable measurements given the extreme operating environments, the small size of the defects and the cyclic melting and heating of the material, caused by subsequently deposited layers. A remote and couplant-free ultrasonic inspection technique using bulk waves that can image near-surface defects could address these in-process inspection requirements. Laser induced phased arrays (LIPA) generate and detect ultrasound based on laser ultrasonics principles, while the array is synthesised in post-processing. However, when using LIPAs for inspection, the surface acoustic waves (SAWs) interfere with the bulk wave modes giving rise to crosstalk and artefacts, which makes near-surface defect imaging difficult. This work experimentally validates and compares five techniques for SAW suppression: amplitude thresholding, mean waveform subtraction, principal component subtraction, frequency-wavenumber filtering, and phase coherence imaging. SAW suppression is demonstrated in ultrasonic images of transverse waves based on 71-element LIPA data synthesised on a Ti-6Al-4V directed energy deposition-arc (DED-Arc/Ti6Al4V) sample with a ∼1 mm diameter side drilled hole, located at ∼4 mm below the inspected surface. The reported results show that the principal component subtraction approach achieved the highest ‘signal-to-crosstalk ratio’ improvement of 16 dB, while successfully suppressing the SAW.