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# Deflection of simply supported plate with multiple points of application

## Deflection of simply supported plate with multiple points of application

(OP)
How can I estimate the deflection at the center of a simply support plate (and a sandwich one) with multiple points but same intensity of load application?

The points of application are symmetrical and form the shape of a rectangle and the loading at each point is the same.

An approximation by using quasi-isotropic layups is acceptable.

### RE: Deflection of simply supported plate with multiple points of application

One method used by the infamous evil genius MW in the 1980s at Boeing was to add up the point loads and divide by the plate area and use that pressure with a simply supported plate under pressure formula from Roark. Roark also has formulas for plates with a rectangular area in the center under pressure. Bear in mind that MW was/is an evil genius...

(OP)
Who is this MW?

### RE: Deflection of simply supported plate with multiple points of application

RP - what Boeing site was he at?

For OP, think Roark has solution for plate loaded with an offset point load. For multiple loads just superimpose solutions.

### RE: Deflection of simply supported plate with multiple points of application

This was 757 so Renton (I was on the -300).

Superposing multiple cases was the sort of thing that MW avoided. He'd rather do something that seemed initially to make no sense to us but would give him the results he needed much more rapidly. He also took KISS to extremes with no explanations and diagrams of what was analysed that often bore little apparent similarity to what was actually there. His final result was often uncannily similar to a much more complicated (and time consuming) analysis using more conventional methods generating many more pages of calcs. Brilliant and dangerous.

### RE: Deflection of simply supported plate with multiple points of application

Well, '80s were before spreadsheets. Now it should be easy to set up superposition of cases.

### RE: Deflection of simply supported plate with multiple points of application

Unless he retired he must have found even more scope for his (comsiderable) creativity with PCs and spreadsheets. One of his methods was to assess the capacity (in terms of life) of each of parallel loadpaths in fatigue (Boeing had good methodology for this) and then share a static load between them accordingly (all with no explanation - that really tested us trying to see what he'd been up to). The original 757 didn't have that much composite either which would have given him even more freedom.

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