资源描述
单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,小结,圆轴(圆筒),闭口薄壁,开口薄壁,3.3,直杆扭转的强度和刚度计算,3.3.1,直杆扭转的强度条件,塑性材料:,脆性材料:,W,P,:,抗扭截面系数,3.3.2,圆轴扭转的合理截面,减缓应力集中:,3.3.3,圆轴扭转破坏现象分析,低碳钢,:,铸铁,:,斜截面应力:,3.3.4,刚度条件,精密机器的轴:,一般传动轴:,W,P,C,圆轴,圆筒,闭口薄壁,开口薄壁,矩形,矩形截面杆的扭转:,a,a,/,b,1,1.5,2,3,4,6,8,10,0.208,0.231,0.246,0.267,0.282,0.299,0.307,0.313,0.333,0.140,0.196,0.229,0.281,0.299,0.307,0.307,0.313,0.333,轴的动力传递,已知:传递的功率,N,k,(kW),和转速,n(,转/,分),,求:使轴发生扭转的外力偶矩,T.,每分钟做功:,电机传动轴,D=40mm,,,N,k,=30kW,n=1400r/min;,轴:,45,#,钢:,=40,MPa,G=8,10,4,MPa,=2,/m,。,校核强度、刚度。,例,传动轴,3.3.5,密圈螺旋弹簧计算,已知:弹簧平均直径,D,(R),,簧杆直径,d,,,弹簧有效圈数,n,,,材料剪切模量,G,求:弹簧应力和变形公式,.,簧杆的斜度,d,簧杆内的应力,:,不计剪力,计及剪力,弹簧的变形,:,刚度:,簧杆的强度条件,:,常用弹簧钢:,铬钒合金弹簧钢:,增加,n,,加大,D,,减小,k,作业:,薄壁强度:4.38,传动轴:,3.6-12,弹簧:,4.49,
展开阅读全文