n-组合变形322课件

1、(1) 确定危险截面确定危险截面 , 用截面法计算危险截面用截面法计算危险截面上的内力上的内力 .(2) 确定危险截面上的危险点确定危险截面上的危险点 , 分析危险分析危险点的应力状态点的应力状态 . (3) 根据适当的强度准则计算组合变形杆根据适当的强度准则计算组合变形杆件的强度件的强度 .强度计算包含三个方面的内容强度计算包含三个方面的内容 (The calculation of strength for a bar involes three parts ) : ABFor the ductile materials :NMT4)(223MNeq3224eq4223eq3)(224MNe

2、qNMTNMTN MTANNzMWMpTWT)(4)(223pzeqWTWMAN)(3)(224pzeqWTWMANVery important formulasNM :PFN4PhM6/)2/(4/2/2maxhbPhbhPWMAFzNAPbhP8)62( bbhPAPN22maxmax66hbPebhPeWMM0NM062bhPhbPebe61WPeWMMbbaaEEWPeAPMNa)(baAP21WPeAPMNb)(baE2APN)(baEAP2)()(babaEWPe221kN4322.)(baEAP)(baPWEe2mm42122.)(baPEbh)(4)(223pNeqWTAF)(

3、3)(224pNeqWTAFNTWFNELWpGITLLGITp)(4)(223pNeqWTAF)(4)(22LWGIAWpp222)4(/dWdGL222)4()1(2dWdEMTMT)(4)(223pzeqWTWM)(3)(224pzeqWTWM MTMT1223TMWzeq75.01224TMWzeqA2qLM 221qLT 22431TMW312198qLd22223214332qLqLd19832dqLaGPM)(21maxPDT21 222222eq3211DPaGPWTMW)(332dW 022222222WGaPGaDaP)()(kN696.PzzMWMzmaxyyMWMyma

4、xmaxmaxzzyyWMWMA A A AzzyyWMWMmax06622bMhMhbyz289.h232224366bMbMMhyzz6622hbMbhMzyAFor the circular and regular-polygon cross section , there is no skew bending . The bending is plane bending !zMyMyMzMiMMmaxWM1M2M3MMMzMyM22maxWMMzy aPT1LPMz12PN aPMy2MPa45241631max.daPWTpA A AP1aA例例 求图示结构求图示结构 A 截面危险点的截面危险点的第三强度相当应力第三强度相当应力。222122)()(aPLPMMMzy2221332)()(aPLPdWMMMPa531422.dPANNMPa6599.NMMPa0111422eq3.MPa1298.A2PN aPMy2LPMz1例 求图示结构求图示结构 A 截面危险点的截面危险点的第三强度相当应力。第三强度相当应力。一般非偏心拉伸和压缩的组合问题中，轴力的影响也可忽略不计。bbbhPNxPMyPMyxyyxxMWMWMmax6622hbxPbhyPhybxbhP606maxhybxbhPbhPMN16hybxxy