CALCULATION FOR BENDING & DEFLECTION IN PLATES

[LATHISH]

Need a calculation or reference to determine deflection & stress in beams & plates for various loading calculations.

Currently I am using machinery's hand book 25th edition.pg no 235 for beams & pg no 267 for plates.

 

[robyengIT]

fo beams see file attached.

Fo plates : "Roark's formulas for stress and strain" and another book by Richard Bares "Analysis of beams grid and orthotropic plates by Guyon-Massonnet-Bares method"

 

[Shu Jiang PEng SE]

The formula are acceptable for beam calculation, however you should be cautions when they are applied to plate calculation (especially when the ratio of plate span over plate thickness is large). The membrane force may play a big role in thin plate and the formula mentioned do not account the membrane effect.

 

[msquared48]

Chapter 10 of Roark's "Formulas for Stress and Strain", fifth edition, does discuss plates.

Mike McCann, PE, SE (WA)

 

[Shu Jiang PEng SE]

Mike, I agree with you. The formula are applicable to plate in some cases.
The limitation listed in the book "(2) ..........., and the maximum deflection is not more than about one-half the thickness;" is used to make sure the plate is not thin plate (compared to the plate span), The membrane force can be ignored in that case.

 

[rb1957]

yes, "plate" beams are limited to small deflections. large deflections are different (obviously!) ... could be membrane load but some structures (like a plate on a roller) won't develop membrane reactions.

another day in paradise, or is paradise one day closer ?

 

[LATHISH]

Thank you all