《材料力学》中一共有4种基本的内力图：轴力图、扭矩图、剪力图和弯矩图，这些内力图的画法既是重点，又是难点，要求学生牢牢掌握。对于内力图的作法，教科书上普遍采用“截面法”，即先通过作截面求出内力然后作图。频繁的作截面不但降低了作图速度，而且使错误增多，降低了 There are totally 4 kinds of internal force diagrams in “Mechanics of Materials”: Axial Force Diagram, Torque Diagram, Shear Force Diagram and Moment Diagram. These internal force diagrams are both important and difficult points, requiring students to grasp them firmly. For the practice of internal force map, the textbook commonly used “cross-sectional method”, that is, first through the cross-section to find the internal force and then mapping. Frequent cross-section not only reduces the drawing speed, but also make mistakes increase, reduced