Roark's Formulas for Stress and Strain

[broekie]

I need help interpreting a formula in Roark's book. On page 472, Table 26, case 11d, the formula for the maximum stress contains a variable "q".

My question is: For the triangular loading shown in the diagram, what is "q"? The total load on the plate? The maximum load at the base of the plate? Obviously, for a uniformly distributed load, "q" is simple. However, I can't seem to find any description in the book for what "q" is when the load is triangular, so I thought that someone out there with more experience might be able to help.

Thanks in advance.

 

[JStephen]

q should be the maximum pressure. It is shown on some of the other load cases like 1d and 1e, and defined as pressure in Table 24 in the "Notation" section. The equation should be dimensionally correct, as another check.

I'm assuming your book has same table numbering and all as my Fifth Edition.

 

[RARWOOD]

I think q is the load per unit area. On page 458 of the sixth edition the information for table 26 refers you back to table 24 for the notation definition.

Table 24 defines it as the load per unit area.

The problem I always had with Roark's book was that in most cases where I used one of the formulas I did not have a method to verify the answer. So if I used an incorrect value for one of the coefficients I would not know it.

 

[prex]

Look at cases 1d and 1e of the same table: q is clearly defined in the figure as the maximum of the triangular distribution.

Look also in the site below, under Plates -> Simple bending -> Rectangular -> 2 adj.clamped,2 free -> Hydro load for the case that interests you.

prex

http://www.xcalcs.com

Online tools for structural design