How to calculate deflection of a beam

CosmosExpress doesn't give deflection numbers (yet) but I use a small program called BeamBoy to do most of that kind of stuff. If your beam isn't something standard, you can get your moments of inertia values from SW and plug them into BB.

WT

Buy a 'Mechanics of Materials' Engineering book. Or Roark's Formulas for Stress and Strain It is straight forward to calculate the deflection using basic Simple Bending theory, particularly for something as straight forward as a 'C' Section. Most text books will give you the 'I-value' for standard sections, the books will show you how to calculate the 'I value' and determine the position of the neutral axis of the section, also Solid works will give you the 'I-Value' for the various planes in your section.

Hope this is of use.

Ron,

If I understand your problem correctly to be the deflection of a curved beam - then it is more complicated than a straight beam. The neutral axis shifts towards the inside radius by a small value known as 'e' (eccentricity). Determining this value is somewhat complex and only approximate in the simpler solutions. The easiest answer could be had by borrowing an FEA program such as Cosmos or Visual Nastran. Once you have the model, it would only take 3 minutes to obtain the deflection.

Sincerely, Jerry Forcier

R> I have a c-shaped beam. Is there an easy way to use SolidWorks to calculate

Hmmm, interesting - is the C shape the shape of the beam material (my interpretation), or is the C shape a bent shape?

WT

My interpretation was that it was the beam profile, as in a channel section.

For this the deflection is purely the relationship between the Length, Load (type, position), Fixing (Simply Supported, Cantilevered etc) and Section (I-Beam, Equal Leg etc)

However, that said if you are looking at a curved beam and do have access to an FEA package then the time v's effort aspect of solving this type of problem, it is probably easier to solve with an FEA package, as long as the user can properly interpret the 'answers' that the FEA package offers up.

Setting up an FEA would take longer than running the numbers by hand, if you have the formulas and stuff in front of you. Here's a calculator on efunda that will do the math for you, and if you look in the moment of inertia link you will see that it has a C-sectioned cross-section to choose for the beam type (see here

Hope this helps, Mike

If you are just looking at the deflection of the beam, then this is very easy and quick to setup and run. Basically, define the curve and use beam elements which most FEA packages have std libraries of.

I would still advocate the use of theory, even if only to validate that the numbers the FEA package spews out are of a realistic magnitude.

1.Draw a section of the beam. 2.Use SW Section Properties to determine the moment of inertia about the axis the bending moment acts.

1. In an assembly turn on the Toolbox addin.
2. Click on Beam Calculation
3. Select the loading case closest to the one you seek an answer for.
4. Enter data, modulus, moment of inertia, load and length
5. Click Solve
6. Deflection will appear in empty box.

Or buy Roark and Young, AISC manual or any structures text.

Note that if the load is not acting through the shear center you will get out of plane deflections not accounted for above.

Note also that if you don't meet certain other criteria you can get buckling of the beam or of the flanges. These may limit the load you can place on the beam.

Note that if the beam is short the above formula will underpredice deflections.