材料力学第四章弯曲内力少课时

1、2345678 910AB对称轴对称轴纵向对称面纵向对称面梁变形后的轴线与梁变形后的轴线与外力在同一平面内外力在同一平面内梁的轴线梁的轴线FRAF1F2FRB11。FAAAA12AAAFRAyAFRAxFFM13 14解：解：q 均布力均布力15 BAalFFFFRBABF , , () , RRR0000 xAxAByAyFFFaMFlF laFFl16MFRAxFABFmmxRAyFSCFFRBFSCM() , , SRR00yAyCAyF laFFFlMMFx17FSdxmmFS+dxmmFSFS18；mm+MMmm（受压）（受压）MM190AMFRBBdEDAabclCFF1F2FRA

2、021R bFaFlFB0BM0)()(21R blFalFlFAlblFalFFA)()(21R lbFaFFB21R 20 BdEDAabclCFF1F2FRAAEcFSEFRA00SR EAyFF,F0, 0R cFMMAEEAEFFRS cFMAE R21AEcFSEFRAa-cb-cCDl-cBEFSEF1F2 0yF021RS FFFFBE0ME0)()()(21R McbFcaFclFEB)()()(21RcbFcaFclFMBE RBEFFFF 21S22 BdEDAabclCFF1F2FRAFdBFSFMFFRB,SRR0000yFBFFBFFFMMFdBFFFRS dFMB

3、FR 23 niiFF左（右）1S 24 mkkiniiMaFM左（右）左（右）左（右）左（右）1125 26 xFS(x)FS 图的坐标系图的坐标系OM 图的坐标系图的坐标系xOM(x)2713kNR AF23R BF1( ) () ( )3S01Fxx2ABC1m1mFRAFRBM1mFD2( ) () ( )3 S22Fxx3+-1/3kN2/3kN28ABC1m1mFRAFRBM1mFD+-1/3kN2/3kN1( ) (01)3RAM xFxxx1( )1 (12)3RAM xFxMxx2( )(3)-2 (23)3RBM xFxxx 2/3kN.m1/3kN.m+-1/3kN.m2

4、9xyq(x)FM30 xyq(x)FMFS(x)M(x)FS(x)+dFS(x)M(x)+dM(x)mmnnq(x)C .nxmmn dx3102d)d(d )()( )(d)( 0 S xxxqxxFxMxMxMMCFS(x)M(x)FS(x)+dFS(x)M(x)+dM(x)mmnnq(x)C0d)()(d)()( 0SSS xxqxFxFxFFy )(d)(dSxqxxF)(d)(dSxFxxM32)(d)(dSxqxxF)(d)(dSxFxxM)(d)(d22xqxxM33)(d)(dSxqxxF ( )( )2211SddxxxxFxq xx()()( )21S2S1dxxFxFxq xx34)(d)(dSxFxxM( )()()21S21dxxFxxM xM x()()( )21S2S1dxxFxFxq xx)()(2S1SxFxF35k623R.FA kN27R BFBACD2001151265FFFF23123.61.727+4.723.11+36 FEqABCD0.21.612kN806 . 11005 . 0RR BAFF37FEqABCD0.21.612+80kN80kN161648+kN80RR BAFF383m4mABCDE4m4mFRAFRBF1=2kNq=1kN/mM=10kNmF2=2kNkN7R AFkN5R BF393m4mABCDE4m4