解:由题意可知Cs钢=3230m/s Cs有=2730m/s β=45°
α=sin-1( (2730/3230) sin45°)=36.7°
λ=c/f=3230×103/2.5×106=1.29mm
K1探头cosβ/cosα=0.88
根据公式得:
$$N = \frac{A}{\pi \lambda } \times \frac{\cos \beta}{\cos \alpha} = \frac{14 \times 16}{3.14 \times 1.29} \times 0.88 = 48.7 \, \text{mm}$$󠅅󠅃󠄵󠅂󠄪󠇖󠆨󠆨󠇕󠆞󠆒󠅬󠇘󠆭󠆘󠇙󠆝󠅵󠇗󠆭󠆁󠄐󠇗󠅹󠅸󠇖󠆍󠅳󠇖󠅹󠅰󠇖󠆌󠅹


