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无损检测编辑部:你刊1981年第4期[问与答(2)]关于《为什么孔径相同的平底孔在声程相差一倍时反射声压的分贝差不是12dB?》的解答中,我认为有欠妥的地方,特提出来与作者及同志们共同商讨.由超声波探伤的物理基础知道,计算圆盘源在固体介质中主声束的半扩散角公式为θ.(?)sin~(-1)1.2λ/D.由图中直角三角形△oab 可获得未扩散区 b 的声场距离。
Nondestructive Testing Editorial Department: No. 4, Issue 1981, No. 4 (in Chinese) [Questions and Answers (2)] In the answer to the question “why the flat-bottomed holes with the same aperture have a decibel difference in the reflected sound pressure when the sound path is doubled?” Considered defective, special mention and author and comrades discussed by the physical basis of ultrasonic flaw detection know, the disc source in the solid medium of the half-diffusion angle of the main beam angle formula is θ (?) Sin ~ (-1) 1.2λ / D. The sound field distance of the non-diffused area b can be obtained from the right triangle △ oab in the figure.