Plate Panel Coefficients

A rectangular panel under uniform pressure, for a Poisson’s ratio of 0.3. Deflection is w = α·p·b⁴/D and bending stress σ = β·p·b²/t², where b is the SHORT side, a the long one, and D = Et³/(12(1−ν²)). The short side is squared, so it is the dimension that matters: halve the stiffener spacing and the stress quarters.

Simply supported panels are worst at the centre. Clamped panels are worst at the middle of the long edge — on a welded panel, at the toe of the weld — and that edge value is the one to design the weld against; the centre value is given too because that is where the plate yields first in the field.

a/b	α simple	β simple (centre)	α clamped	β clamped (edge)	β clamped (centre)
1.0	0.00406	0.287	0.00127	0.308	0.137
1.1	0.00487	0.333	0.00151	0.349	0.160
1.2	0.00565	0.376	0.00172	0.384	0.180
1.3	0.00639	0.416	0.00191	0.413	0.196
1.4	0.00708	0.453	0.00207	0.436	0.210
1.5	0.00772	0.487	0.00220	0.454	0.221
1.6	0.00831	0.517	0.00230	0.469	0.229
1.8	0.00932	0.569	0.00245	0.488	0.241
2.0	0.01013	0.610	0.00253	0.498	0.247
2.5	0.01150	0.678	0.00261	0.505	0.252
3.0	0.01223	0.713	0.00262	0.503	0.251
4.0	0.01282	0.741	0.00260	0.498	0.250
5 or more	0.01302	0.750	0.00260	0.500	0.250

Plating welded to stiffeners lies between the two conditions: clamped for stress at the weld, simply supported as the safe bound on deflection. Past a/b ≈ 5 the panel bends like a strip across its short side and the coefficients stop moving — the last row is the exact strip solution (5pb⁴/384D with M = pb²/8 simple; pb⁴/384D with M = pb²/12 at a clamped edge).

Work a panel with the plate panel tool.

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