疲勞與斷裂 第五章 斷裂失效與斷裂控制設(shè)計(1)ppt課件

1、中心裂紋中心裂紋s sWBs s邊裂紋邊裂紋s ss s外表裂紋外表裂紋2cts ss s裂紋尺寸裂紋尺寸運(yùn)用時間運(yùn)用時間a) a) 裂紋擴(kuò)展曲線裂紋擴(kuò)展曲線剩余強(qiáng)度剩余強(qiáng)度裂紋尺寸裂紋尺寸b) b) 剩余強(qiáng)度曲線剩余強(qiáng)度曲線裂紋的裂紋的三種根三種根本受載本受載方式：方式：s szxy yz zxy yz zs ss sx xy y2adxdyrs 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=-221cos q qq

2、q232sin sin(5-1)(5-1)s sp pf f q qijijKr= =12( )Ka1= =s sp ps ss sx xy y2adxdyrKa f a W1= =s s p p( ,.)作用作用( ( 、a)a)越大，抗力越大，抗力(K1C )(K1C )越低，越能夠斷裂越低，越能夠斷裂。s sp pf f q qijijKr= =12( )Ka1= =s sp p作用作用 K=f (s, a, .) 由力學(xué)分析得到；由力學(xué)分析得到； 彈性力學(xué)方法，有限元法，手冊等。彈性力學(xué)方法，有限元法，手冊等。L=4WWP三點(diǎn)彎曲三點(diǎn)彎曲B=W/2)( 7 .38)( 6 .37)(

3、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 0.25WPPW1.25W1.2W0.55W。PP實(shí)驗(yàn)機(jī)實(shí)驗(yàn)機(jī)引伸計輸出引伸計輸出V VPmaxP0VP500P5PmaxPmaxBWKBKc)(57.14)(18.14)(20. 8)(735. 1090. 1)(432WaWaWaWaWaf+ +- -+ +- -= =)(2321WafaBWPLKp p= = 將

4、將a/W=32/60=0.533， PQ= 56kN 代入，算得：代入，算得： KQ=90.5 MPa)(1x xp ps sFaK = =)2/sec()(pxpxx x= =F)(1x xp ps sFaK = =KKK + + = =PPKK WPP05. 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 )0.025/01. 03. 637. 1 (005. 014. 3025. 060)/3. 637. 1 (1+ += =+ += =WeaWKPccp ps sp pf f q qijijKr= =12( )Ka1= =s sp ps ss sx xy y2adxdyrs s s sq qyar= =+ +221cos q qq q232sin sint ts sq qq qq qxyar= =22232sin cos coss