第十一章交变应力

1、AFts s静平衡位置静平衡位置tts ss s sts s maxs s minFF tzAtry sintIrMIyM s ssints ss s1s s2s s3s s4s s1O 裂纹源裂纹源光滑区光滑区粗糙区粗糙区 一个应力循环一个应力循环Os sts ss smaxminr maxminrs s maxs s minO一个应力循环一个应力循环s sts s maxs s mins s as sa2minmaxas ss ss s 2minmaxms ss ss saOs smaxs smins st1maxmins ss srmaxas ss s 0m s s1r0maxmins

2、ss sr2maxmas ss ss s Os smaxs smin=0s st1r0a s smaxms ss sOs smaxs smin=0ts s.maxmax24 58300561MPa0 0115FAs s .minmin24 55800537 2MPa0 0115FAs s MPa1225375612minmaxa s ss ss sMPa54925375612minmaxm s ss ss s957. 0561537maxmins ss sr s s-1s smax，1N11s smax，2N22Ns smaxFFFFaabs ss s 1max,2max,s s1max,s

3、ss s-1s smax，1s smax，2N1N212Ns smaxFa1()()dkK-1-1s ss ss s()()1 d1 kK s sK K()ds ss s s s-1-1-1-1()()-1 d s s s s- -1 1101 s s s ss ss sKs sKs s 1s srK 01 (Calculation of the fatigue strength of the member under symmetric cycles)1011 1s s s ss ss ss sKnn1011 1 Knn1maxs ss snKn 1max s ss s s ss ss sn

4、Kn 1max f f50f f40r=525. 14050dD125. 0405dr77. 0s s MPa1000bs s55. 1s sKMPa900bs s55. 1s sKMPa920bs s55. 1s sKMPa1000bs s28. 1 KMPa900bs s25. 1 KMPa920bs s26. 1)900920(90010025. 128. 125. 1 K81. 0 .MMf f50f f40r=5MPa2 .6505. 0328003minmax s ss sWM1maxmins ss sr4 . 1s sKMPa600 ; 15. 0 ; 4 . 1bdrdDs s

5、79. 0s s nKn 12. 22504 . 15 .6294. 079. 0 1maxs ss s s ss ss s 107r0.25r0r-1 s sas smOs sas smPmaxmas ss ss s rr 11tanminmaxminmaxmas ss ss ss ss ss s s sas smOs sas smPP A20s sCs sbBs sas smOs sas smPP2/2/tan001s ss ss s s s m1arrs s s ss ss s ma,s ss s OIPIrGHOHs s s ssOBHIJCFKGPEALs sms sms sas s

6、as ssmma1ms ss s s s s ss ss ss ss s Krama1s ss s s s s ss ss ss s KGHma smmmarrGHOHGHns sssssssssssss)(rm1s s s s s ss ss s KGHmmarGHs ss ss s nn s snKn ma1 s s ma1s s s s s ss ss ss ss s Knmma1ms ss s s s s ss ss ss ss s Krama1s ss s s s s ss ss ss s KGHma smmmarrGHOHGHns sssssssssssss( .).3330 04

7、6 28 10 m3232dW- -6 6 MPa5 .811028. 65126maxmax WMs sMPa3 .1651maxmin s ss s2 . 051maxmin s ss srmm2截面截面mm40MPa9 .4823 .165 .812minmaxm s ss ss sMPa6 .322minmaxa s ss ss s05. 04020 ddMPa950b s s18. 2 s sK77. 0 s s 77. 0 21. 49 .482 . 06 .32177. 018. 2430ma1 s s s s s ss ss ss ss sKn.ssmax5406 6281 5

8、nns ss ss snnnnnn 22 s s s ss s s sn nR5TTMM50600.40.4MPa3 .81103 .121000MPa3 .81103 .1210006minmin6maxmax WMWMs ss s.3330 0512 3 10 m3232dW- -6 6 1maxmin s ss sr.333t0 0524 6 10 m1616dW- -6 6 .6maxmax6t150061 10 Pa61MPa24 6 10TW 0min 0maxminmin rMPa5 .302maxa MPa5 .302maxm 1 . 0105, 2 . 15060 dRdD55. 1 s sK24. 1 K78. 0,73. 0 s s 1 1 . 0 38. 23 .81