| 講演要旨(和文) | | コンクリート構造物の非破壊検査にはハンマー法がいまだに使われている。しかしながら、高い場所の検査には困難が伴っていた。そのため、遠距離から叩き点検と同程度の欠陥検知精度をもつ遠距離非接触音響探査法の検討を行ってきた。これはスキャニング振動系（SLDV）と長距離音響放射装置（LRAD）を組み合わせた手法であり、LRADの持つ面加振能力とSLDVのもつ2次元計測性能を生かして比較的狭い領域の探査を精密に行うのに適している。一方で、SLDVによる2次元的計測性能は静止状態でレーザ光のアライメントをとる必要があるため、移動計測には適していないこと、およびLRAD自体の指向特性は1kHzで±15度と優れてはいるが、実用を考えた場合の周囲への騒音や対象物に対する角度依存性等の問題がある。そこで、非接触音響探査法の第2の構成法として強力超音波音源とシングルポイント用LDVを組み合わせた場合を検討した。 |
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| | 講演要旨(英文) | | The hammer method is still used for the non-destructive test of the concrete structures. However, difficulty had followed on the inspection of the high place. Therefore, the long distance non-contact acoustic inspection method with defective detection accuracy comparable as the hammer method has been examined. This is the technique of having combined a scanning laser Doppler vibrometer (SLDV) and a long-distance acoustic device (LRAD). It is suitable for searching a comparatively narrow region precisely taking advantage of plane excition ability of LRAD, and the two-dimensional scanning capability of SLDV. On the other hand, since the two-dimensional scanning performance by SLDV needs to take alignment of laser light in the state where it was stood still, it is not suitable for measurement while moving. And although the directional characteristics of the LRAD itself are excellent in 1 kHz with plus minus 15 degree, there are problems, such as angular dependence nature to a subject and noise to the circumference at the time of considering practical use. Then, the case where a strong ultrasonic sound source and LDV for a single point were combined as the 2nd construction of the non-contact acoustic inspection method was examined. |
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