How Do You Interpret Shear and Moment Diagrams?

[skaterbasist]

I passed my statics course and am currently taking material stength course.

The thing that has been on my head is the fact that, although I know how to do shear and bending moment diagrams... I do not know how to READ them. In other words, the diagrams don't mean anything to me.

For example, in the diagram below, the maximum moment is being developed under what axis? The z-axis perpendicular to the A support or the z-axis perpendicular to the B support?

I'm not even sure if my question makes any sense. It just bugs me to know that I know how to SOLVE these problems and develop the diagrams, but they're practically meaningless to me.

ANY help would be greatly appreciated!

 

[Mapes]

If you know how to make the diagrams, it's just a matter of practice and repetition because you can "read" them just by looking at them.

The maximum moment is at the location of the force F, the location of largest value on the bending moment diagram.

 

[viscousflow]

For example, in the diagram below, the maximum moment is being developed under what axis? The z-axis perpendicular to the A support or the z-axis perpendicular to the B support?

Th moment vector points out of plane (perpendicular to the page).

 

[PhanthomJay]

For example, in the diagram below, the maximum moment is being developed under what axis? The z-axis perpendicular to the A support or the z-axis perpendicular to the B support?

The internal bending moment in this example acts about the z axis at the point of application of the load. It is counterclockwise acting on the left part of the beam (vectorially pointing outward), and clockwise acting on the right part of the beam (vectorially pointing inward), in accordance with Newton's 1st and 3rd laws. By convention, the moment is considered as a positive moment. You should draw a free body diagram of the section of the beam from the left support to just left of the applied load, to prove this yourself, using Newton 1. Then draw a free body diagram of section of the beam from just right of the applied load to the right support, and proceed in a similar manner.

 

[alphy]

Congratulations on passing your statics course and taking on the challenge of material strength! It is completely understandable to feel a bit lost when it comes to reading shear and moment diagrams. These diagrams are an essential tool in engineering and understanding how to interpret them is crucial for designing safe and efficient structures.

To answer your question, the maximum moment is being developed under the z-axis perpendicular to the A support. This is because the moment is caused by the force acting on the beam, which is perpendicular to the A support. It is important to note that the maximum moment can vary along the beam, so it is important to carefully analyze the diagram and understand the forces and supports at each section.

To better understand how to read shear and moment diagrams, it may be helpful to review the fundamental principles of statics and mechanics of materials. This will provide a solid foundation for interpreting these diagrams and understanding the underlying concepts.

Additionally, practice makes perfect! As you continue to work with these diagrams and encounter different types of structures, you will become more comfortable and confident in reading and interpreting them. Don't hesitate to ask for help from your peers or professor if you come across any challenges.

Overall, it is great that you are recognizing the importance of being able to read these diagrams and seeking help to improve your understanding. Keep practicing and asking questions, and you will become proficient in reading shear and moment diagrams in no time. Best of luck in your material strength course!