(1.6.2)--3.1材料力学材料力学.ppt

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1、Chapter 3 Torsion Mechanics of Materials3.1 IntroductionIntroductionA large crankshaft is needed to turn the propeller shaft to power large ships.The propeller shaft develops torsional stresses and twisting deformationsduring rotation.ExamplesIntroductionTorsionthe twisting of a straight bar when it

2、 is loaded by twisting moments or torques that tend to produce rotation about the longitudinal axes of the bar.Introductiontorque TCylindrical members that are subjected to torques and transmit power through rotation are called shafts.Couple:the pair of forces that tends to twist the bar about its l

3、ongitudinal axis.Torsional loadingIntroductionMoment of a couple:T(Nm)=Force(N)x Arm(m)T1=P1d1 T2=P2d2Torsional loadingIntroductionRepresentation of the moment of a couple:a vector with a double-headed arrowright-hand rule:using your right hand,let your fingers curl in the direction of the moment,and then your thumb will point in the direction of the vector.a curved arrow acting in the direction of rotationQ:Torsional deformation in engineering?IntroductionEnd