工程力学轴力图扭矩图剪力图的画法？

病理医师

大学工程力学
原文地址：https://www.zhihu.com/question/27667332

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Determining shear and moment diagrams is an essential skill for any engineer. Unfortunately, it's probably the one structural analysis skill most students struggle with most.
确定剪切图和弯矩图是任何工程师的基本技能。不幸的是，这可能是大多数学生最难掌握的一项结构分析技能。
This is a problem. Without understanding the shear forces and bending moments developed in a structure you can't complete a design. Shear force and bending moment diagrams tell us about the underlying state of stress in the structure. So naturally, they’re the starting point in any design process.
这是一个问题。如果不了解结构中产生的剪力和弯矩，就无法完成设计。剪力和弯矩图告诉我们结构中应力的基本状态。因此，自然而然地，它们是任何设计过程的起点。
Another reason every graduating engineer needs to have a solid grasp of shear forces and bending moments is that they're absolutely going to be tested in almost every graduate interview. The quickest way to tell a great CV writer from a great graduate engineer is to ask them to sketch a qualitative bending moment diagram for a given structure and load combination!
每个即将毕业的工程师都需要牢牢掌握剪切力和弯矩的另一个原因是，他们绝对会在几乎每次毕业生面试中进行测试。分辨优秀简历作者和优秀毕业工程师，最快的方法是让他们为给定的结构和荷载组合绘制一个定性的弯矩图！
Shear and bending moment diagrams are analytical tools used in conjunction with structural analysis to help perform structural design by determining the value of shear force and bending moment at a given point of a structural element such as a beam. These diagrams can be used to easily determine the type, size, and material of a member in a structure so that a given set of loads can be supported without structural failure. Another application of shear and moment diagrams is that the deflection of a beam can be easily determined using either the moment area method or the conjugate beam method.
剪力矩图和弯矩图是与结构分析结合使用的分析工具，通过确定结构单元（如梁）的给定点处的剪力和弯矩值来帮助进行结构设计。这些图表可用于轻松确定结构中杆件的类型、尺寸和材料，以便可以支撑一组给定的荷载而不会发生结构故障。剪切图和弯矩图的另一个应用是，可以使用弯矩面积法或共轭梁法轻松确定梁的挠度。
Shear Force – A positive internal shear force causes a clockwise rotation of the beam segment. (i.e., it pushes a left-facing cross-section upward or a right-facing cross-section downward).
剪切力 – 正的内部剪切力导致梁段顺时针旋转。（即，它将朝左的横截面向上推或向右的横截面向下推）。
Bending Moment – A positive internal moment causes compression in the top fibers of the segment (i.e., clockwise on a left-facing cross-section or counter-clockwise on a right-facing cross-section).
弯矩 – 正的内弯矩会在以下部位造成压缩段的顶部纤维（即顺时针方向向左或逆时针方向在右向截面）。
what is a Bending Moment? A moment is a rotational force that occurs when a force is applied perpendicularly to a point at a given distance away from that point. It is calculated as the perpendicular force multiplied by the distance from the point. A Bending Moment is simply the bend that occurs in a beam due to a moment.
什么是弯矩？弯矩是一种旋转力，当力垂直作用在离某点一定距离的地方时产生。其计算公式为垂直力乘以与该点的距离。弯矩简单来说就是梁在弯矩作用下发生的弯曲。

长长的路

材料力学是在静力学的基础上，研究构件在已知外力的作用下，其内部受怎样的力，受多大的力，多大的应力，而引起构件发生变形，失效，从而设计出安全可靠工作的零件或构件。材料力学的第一环节就是判断内力，画内力图。
根据构件的受力和变形特点，材料力学常将构件分为，杆、轴、梁三类，杆是以受轴向拉伸与压缩变形为主的构件，其内力是轴力；轴是以承受扭矩为主的构件，其内力是扭矩；梁是以承受横向力，以弯曲变形为主的构件，其内力包括剪力和弯矩。
岐妈用三次课教会你画内力图。


具体详见B站视频：三次课教会画【工程力学·材料力学】内力图——轴力图_哔哩哔哩_bilibili
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检验医师

你是认真的么？这是材料力学的第一个坑啊！！！
推荐看  《材料力学教程》 北京理工大学 .韩斌. 电子工业出版社
个人觉得那里面详讲的微分关系叠加法是应试，工程分析中最实用的方法