1、1234中心裂紋中心裂紋s sWBs s邊裂紋邊裂紋s ss s表面裂紋表面裂紋2cts ss s5裂紋尺寸裂紋尺寸使用時間使用時間a) a) 裂紋擴展曲線裂紋擴展曲線剩余強度剩余強度裂紋尺寸裂紋尺寸b) b) 剩余強度曲線剩余強度曲線6789裂紋的裂紋的三種基三種基本受載本受載形式：形式：s szxy yz zxy yz z10s ss sx xy y2adxdyr11s ss sx xy y2adxdyrs s s sq qyar= =+ +221cos q qq q232sin sint ts sq qq qq qxyar= =22232sin cos coss s s sq qxar=

2、-221cos q qq q232sin sin(5-1)(5-1)12s sp pf f q qijijKr= =12( )Ka1= =s sp ps ss sx xy y2adxdyr131 1Ka f a W1= =s s p p( ,.)14151617作用作用( (s s、a)越大，抗力越大，抗力( ()越低，越可能斷裂越低，越可能斷裂。18192021222324s sp pf f q qijijKr= =12( )Ka1= =s sp p251 12627282930作用作用 K=f (s s, a, .) 由力學分析得到；由力學分析得到； 彈性力學方法，有限元法，手冊等。彈性力

3、學方法，有限元法，手冊等。31L=4WWP三點彎曲（三點彎曲（B=W/2）)( 7 .38)( 6 .37)( 8 .21)( 6 . 4)( 9 . 22/92/72/52/32/ 12/3WaWaWaWaWaBWPLK+-+-=)(639)(1017)( 7 .655)( 5 .185)( 6 .292/92/72/52/32/ 12/ 1WaWaWaWaWaBWPK+-+-=2孔f 0.25WPPW1.25W1.2W0.55W32PP試驗機試驗機引伸計輸出引伸計輸出V33PmaxP0VP500P5PmaxPmax34用工具用工具顯微鏡顯微鏡BW35KBKc363738)(57.14)(1

4、8.14)(20. 8)(735. 1090. 1)(432WaWaWaWaWaf+ +- -+ +- -= =)(2321WafaBWPLKp p= =39 將將a/W=32/60=0.533， 56kN 代入，算得：代入，算得： KQ=90.5 MPa40414243)(1x xp ps sFaK = =)2/sec()(pxpxx x= =F)(1x xp ps sFaK = =444546KKK + + = =PPKK WPP4705. 1(6Pe2/Wap p= Wa/= =x x43239.3072.2155.10231. 012. 1)(x xx xx xx xx x+ +- -+ +- -= =F);(x xp ps sFa= =K tWaP/37. 1p p= =K 48)0.025/01. 03. 637. 1 (005. 014. 3025. 060)/3. 637. 1 (1+ += =+ += =WeaWKPccp p49s sp pf f q qijijKr= =12( )Ka1= =s sp p501 1515253s ss sx xy y2adxdyrs s s sq qyar= =+ +221cos q qq q232sin sint ts sq qq qq qxyar= =22232sin cos coss s