I=质量X垂直轴二次)the moment of inertia

characterize an object's angular acceleration due to torque.

静矩(面积X面内轴一次)

把微元面积与各微元至截面上指定轴线距离乘积的积分称为截面的对指定轴的静矩Sx= ydF。

截面惯性矩

截面惯性矩(I=面积X面内轴二次)

截面惯性矩:the area moment of inertia

characterized an object's ability to resist bending and is required to calculate displacement.

截面各微元面积与各微元至截面某一指定轴线距离二次方乘积的积分Ix= y↑2dF。

截面极惯性矩

截面极惯性矩(Ip=面积X垂直轴二次)。

Ip: the torsional moment of inertia

the polar moment of inertia

截面各微元面积与各微元至垂直于截面的某一指定轴线二次方乘积的积分Ip= P↑2dF。

a quantity to predict an object's ability to resist torsion, to calculate the angular displacement of an object subjected to a torque.

截面惯性矩和极惯性矩的关系

截面对任意一对互相垂直轴的惯性矩之和，等于截面对该二轴交点的极惯性矩Ip=Iy+Iz。