材料力学第八章 组合变形2013

1、11r)(3212r)()()(212132322214r强度理论的统一表达式：强度理论的统一表达式：r r 相当应力相当应力313r l u 拉伸、压缩拉伸、压缩u 剪切剪切u 弯曲弯曲u 扭转扭转 0 AFN zzIyM zzNIyMAF 02FFN 41maxlFM xxFN图图M图图F2F1/4 AFNt WMbmax AFt2 WlFWMb41max WlFAFbtt412max - max maxtt maxcc yzz0z1350FF5050150150yzz0z1350FF5050150150nnFNMyyFFMFFyN22105 .4210)5 . 735( yzz0z150

2、50150150MPa1515FAFN nnFNMyyzz0z15050150)(MPa53105 . 74250max FIMyytz )(MPa53105 .124251max FIzMyyc 5050150150yzz0z1拉拉nnFNMy53105 . 742515 maxmaxtttFF 5050150150yzz0z1拉拉压压nnFNMy53105 .12425maxccFAF 5050150150yzz0z1拉拉压压nnFNMyaaaa112214)2(aFaFAFAFN aa2 22 22 22 22 26 61 12 22 2aFaaFaaaFWMAFN / 8 84 42

3、22 22 2 aFaF/LaABCFBFmxlaABCAAFmmFlA截面截面 C3C4TC3C4C2C1 C2C1A截面截面 C3C4TC3C4C2C1 C2C1u tWTu WMu A截面截面 1C3C4 C2C1TC3C4C2C1(Analysis of strength condition)C1 2222314212)2(2 02 223134 r 2243 r C1 r223134 r2243 r1拉伸（压缩）与扭转的组合拉伸（压缩）与扭转的组合xyzFT2234rtFTAW拉伸（压缩）、弯曲与扭转的组合拉伸（压缩）、弯曲与扭转的组合xyzFMyMzT2234rtFMTAWWWTM

4、WTWMtr2222223)(4)(4 WTMWTWMtr222222475. 0)(3)(3 21623dWWt 1,323DW163DWtABCD1.4m0.6m15kN10kN0.8mABFmABCD1.4m0.6m15kN10kN0.8mmkN156 . 0104 . 115 mkN25 FABFm+15kNm-20kNmmkN20max MmT kN1515)1(3243 DWMPa26.157223 WTMrBACDyz5kN10kN300mm300mm100mmx1.82kN3.64kNBACDyz5kN10kN300mm300mm100mmx1.82kN3.64kNxyzACB

5、D5kN1kNm1.82kN3.64kN10kN1kN.m1CT 图图-My图图0.57CB0.36Mz图图0.2271CBxyzACBD5kN1kNm1.82kN3.64kN10kN1kN.mmkN36. 0mkN57. 0 yByCMMmkN1mkN227. 0 zBzCMMmkN227. 0mkN57. 0zCyC MMCT图图-My图图0.57kNmCB0.36kNmMz图图0.2271CBmkN1mkN36. 0zByB MMmkN1 CBTTmkN063. 122 zByBBMMMmkN36. 022 zCyCCMMM WWTMBBr137275. 0224323dW mm.9 9515110101001001372137232323 36 6 d400400400400mkN4 . 0kN12 mFmkN4 . 0mkN8 . 04 . 08 . 0max21max TFFM WTMr2max2max338.5mmd 400400400mkN4 . 0mkN8 . 04 . 08 . 0max21max TFFMkN203N FF400400400MPa143m