胜录国的具些质 Appendix Properties of Plane Areas
Appendix Ⅰ Properties of Plane Areas
截面的几何性质(Properties of Plane Areas) 附录I截面的几何性质 (Appendix I Properties of plane areas) 1-1截面的静矩和形心(The first moments of the area& centroid of an area) 1-2极惯性矩惯性矩惯性积(Polar moment of inertia Moment of inertia Product of inertia) 1-3平行移轴公式(Parallel-Axis- theorem) 1-4转轴公式(Rotation of axes)
(Properties of Plane Areas) 附录Ⅰ 截面的几何性质 (Appendix Ⅰ Properties of plane areas) §1-1 截面的静矩和形心(The first moments of the area & centroid of an area) §1-4 转轴公式 (Rotation of axes) §1-2 极惯性矩 惯性矩 惯性积 (Polar moment of inertia Moment of inertia Product of inertia) §1-3平行移轴公式 (Parallel-Axis theorem)
國的肌何质( Properties of Plane Areas)國□ §1-1截面的静矩和形心 CThe first moment of the area centroid of an area 静矩( The first moment of the area) 截面对y,z轴的静矩为 zdA i dA ydA 静矩可正,可负,也可能等于零
(Properties of Plane Areas) §1-1 截面的静矩和形心 (The first moment of the area & centroid of an area) 一、静矩(The first moment of the area ） O y z dA y z 截面对 y , z 轴的静矩为 静矩可正，可负，也可能等于零. = A S y zdA = A Sz ydA
國的肌何质( Properties of Plane Areas)國□ 二、截面的形心( Centroid of an area) ZdA s J da da S J A A S,=Az S= Ay (1)若截面对某一轴的静矩等于零,则该轴必过形心. (2)截面对形心轴的静矩等于零
(Properties of Plane Areas) y z O dA y z 二、截面的形心(Centroid of an area) C z y A S A z A z A y = = d A S A y A y A z = = d S Az y = Sz = Ay （2）截面对形心轴的静矩等于零. （1）若截面对某一轴的静矩等于零，则该轴必过形心
國的肌何质( Properties of Plane Areas)國□ 三、组合截面的静矩和形心 CThe first moments ¢roid of a composite area) 由几个简单图形组成的截面称为组合截面 截面各组成部分对于某一轴的静矩之代数和,等于该截 面对于同一轴的静矩 用
(Properties of Plane Areas) 三、组合截面的静矩和形心 (The first moments ¢roid of a composite area) 由几个简单图形组成的截面称为组合截面. 截面各组成部分对于某一轴的静矩之代数和，等于该截 面对于同一轴的静矩