Model (not calculate) beam deflections

Nov 21, 2006 4 Replies
C

Hi,



I'm wondering if anyone has handled modelling beam / girder deflection in SolidWorks?



I have had reasonable success with simple beams using the 'flex' function; specifying the flex widget on the neutral axis and playing with the angle / radius until the right deflection is achieved.



However in this instance I have a series of vertical deflection data points between support columns, calculated by an external source. In plan view the beam system is not linear; rather it has a couple of angles. In elevation the whole beam is cambered upwards in the mid-section.



One approach to the problem of modelling this system would be to calculate the length alterations and end face angles manually; and then loft a single beam along a guide curve. However this has a number of practical drawbacks; most notably that the data is more easily and appropriately handled as an assembly of sub-beams.



Any clues on how this might be approached? Ideally some sort of distortion / flexure driven by a control line in an assembly of sub-beams; acting on each beam..... Eg. it would be nice to model the beams 'as-built' and then get SolidWorks to show how the deflection affects the overall shape.



Or perhaps a fresh approach?



Cheers.


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T

Sweep the beam section down a spline and put spline points at a distance that gives a result within your acceptable accuracy. If you have external data you can import it to a curve.

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T

The other thought that comes to mind is why not use FEA to do this? Both Cosmos/M and NE Nastran do a nice job of modeling beams. Is it that you are assessing the fit and function after loads are applied instead of strength and stress?

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C

Correct; I'm assessing the fit, rather than conducting a structural analysis.

I did consider using FEA. However as usual there are mitigating circumstances; namely that the data is only in 2-D form and I have a very simple 3D representation from a survey of the as-built girders.

Having done some hand calcs I do not think that modelling the deflections will be practical. Rather I'll use the deflection line to calculate overall change of length in 3D; plus change in angle of each end section. This I can then model.

Thanks for your input and suggestions. Normally I'm creating the data from scratch and therefore would have full geometry and run it through FEA - steel beam so pretty straight forward. However in this instance I'm doing a 'quickie' and only have access to other's (awful) 2D data.

Cheers.

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