Calculating Reaction Forces on Symmetrical Beam

[lottedx]

Hi, first post here, currently a Mech Eng student, learning about Mechanics of Solids. In calculating reaction forces on a symmetrical beam that's simply supported, we've done it in three ways - Macaulay's Bending Moment method, Displacement Finite Element analysis and in ANSYS (computer program based on FEA). Was just wondering when each of these method would be used? Is there a specific situation where one would be more useful than the other or it is more about learning every situation in order to double check answers?

Many thanks for any thoughts on the situation

 

[Studiot]

Hello, lottedx and welcome to Physics Forums.

Well isn't it nice to have more than one method available to calculate something?

When you have more than one method and the different methods yield the same answer, you have a truly independent check.

Obviously you have analysed the same beam each time to compare the methods and found that for a simple situation straightforward substitution into a formula is easiest.

However consider how easy it would be to develop a formula for a beam of variable section (eg tapering), compared to the small change needed to an FE model.

Now consider a complicated structure that will be analysed by FE methods.
How will you know that the FE method is telling the truth?
Answer - by 'calibration' against known cases determined by other methods and/or by obtaining rough results by simpler methods.

Does this help ?

go well

 

[lottedx]

That makes perfect sense, thank you.

Especially as we all have a tendency to take computer answer as gospel, we all know that the answers are only as good as the human input that created them!

That's helpful to know that it is purely different ways to calulate the same things.

Thanks!

 

[yster]

Yes! as my Stress analysis lecturer would say when it comes to FEM- "Junk in Junk out"

 

[kcg231286]

hello sir am a mechanical design engineering student who is trying to use ansys workbench for an simple analysis. i am new to this software.
how can i apply a force in a beam with specific angle. is it possible to apply a inclined force on a component?