放置式探头检测工件时特征频率的计算

1,2,1(1.,266041;2.,430074)(,200436):,,,:;;:TG115.28:A:100026656(2001)0520185205CALCULATIONOFTHECHARACTERISTICFREQUENCYFORTHEINSPECTIONOFSPECIMENBYSPOTPROBESUNJin2li1,2,CHENXin2bo1(1.QingdaoBranch,NavalAeronauticalEngineeringAcademy,Qingdao266041,China;2.HuaZhongUniversityofScienceandTechnology,Wuhan430074,China)YUANHai2yue(HaiyingMachineryPlant,Shanghai200436,China)Abstract:Thespecimenwasconsideredasasemi2infiniteflatsurfacewhentestedbyapointprobe.Thecalculationequationofthecharacteristicfrequencywasderivedbythetheoryofeddycurrentring,whichisofgreatsignificanceinthedeterminationoftheworkingfrequency.Keywords:Eddycurrenttesting;Probe;Frequency,fg,f=(1050)fg,f=(420)fg;,,,f=(1550)fg;,f10fg,fgffg=5066rd2(1):2000209227r,m/mm2d,cm,,,?1,,,1,,,,,58123520015NDTVol.23No.5May2001©1995-2004TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.1,HRLoos,22.1x0,x,y,2(x=0)H0y,,H0=Hmcost(2)H0=Re(ÛH0ejt)ÛH02y,Hx,y,z,5H/5y=0,5H/5z=0¨2ÛH=jÛH,d2ÛHydx2=jH(3),ÛHy=ÛA1e-x+ÛA2ex(4)=j,=+j=j,,==2(5)(4)ÛA1,ÛA2,,x,ÛHy,ÛA2=0;x=0,,ÛA1=Hm,(4)ÛHy=Hme-xe-jx(6),Hy=Re(ÛHyejt)=Hme-xcos(t-x)(7)(6)¨H=J,ÛJz=5ÛHy5x=55x(Hme-xe-jx)=-Hm(1+j)e-xe-jx=-J0e-xe-jx-4(8)J0(x=0)J0=HmJz=-J0e-xcost-x+4(9)J=(-ez)J0e-xcost-x+4(10),ÛEz=ÛJz=-J0e-xe-jx-4(11)2.2,ÛP=12ÛEÛH3|x=0(12)(4)(11)ÛPav=J02Hmej4=J202212+j12=p+jQ(13)p,,p=Re12ÛEzÛH3yx=0=14J20(14)681:©1995-2004TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.QQ=Im12ÛEzÛH3yx=0=14J20(15)(y=1),x=(3)I=ÛJ0ds=0ÛJz1dx=-0J0e-(1+j)xej4dx=-J02(16)3(y=1)(z=1,y=1),(x)R=2pI2=12J20J022=1(17)x=2QI2=1(18),()ab2.32.3.1b4,(10),rJ=J0re-z(19)Jrzr,drI=ksJds=0r+drrJ0re-zdrdz=J0rdr0e-zdz=J0rdr(20)41I=J0rbdrb=(21)(21),rJ0rdrdr,552.3.2ar0,,r=0,,r,,,r,rJ0r[1]J0r=J0brrb4e-41-rrb(0rrb)J0brrb14e141-rrb(rrb)(22)rbrJ0br=rb781:©1995-2004TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.rb0J0brrb4e-41-rrbbdr=J0bba1(23)rbJ0brrb14e141-rrbbdr=J0bba2(24)a1,a2,(23)(24),xeaxdx=eaxa2(ax-1)xmeaxdx=xmeaxa-maxm-1eaxdx(23)(24),a1=0.116758rba2=0.384431rb,aa=a1+a2=0.501189rbr0r0=rb+12(a2-a1)=1.13383rb(25)1a,b,r0,,,,,,662.2,,,,,,(14),5.3,(22),2.14rb0.457rb,,2.14rb0.457rb5.3,,,,,,3fg,,r,r=rb+a2=rb+0.38443rb=1.38443rb(26)d=2r=2.76886rb(1)fg=5066rd2=5066r(2.76886rb10-1)266079rr2b(27)4SMART297,rb=1.25mm,,100mm40mm(),20mm20mm,0.2mm3mmf=(1050)fg,,f=20fg(a)(b)7881:©1995-2004TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.(a)(b)84.1=35.4m/mm2,r1,f=20fg24kHz74.2=10m/mm2,r6000,f=20fg14Hz8,,,fg,:[1],.[M].:,1995.[2].[M].:,1989.[3].[M].:,1989.(MMT),,,20017,8,:1.2.3.()::059222115533,2111528,2230833:059222111528,2233833:0108:361001,,,,9.00(15%),,:99,:200437,:(021)65420775311,:981:©1995-2004TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.