STIFFNESS AND STRENGTH OF FORMED DEEP DRAWN

SHEET METALFEA trade study

3/25/2016Don Blanchet3B Associates339-234-3544

NRCM hydraulic presses

GOALS – FEA simulations Examine various designs for a

large sheet metal cover used for a flight worthy rugged computer.

Requirements - analyses– Shock and vibration natural

frequency– weight– Deflection and stress under internal

pressurization of 1.0 psi

Design parameters 2024 aluminum .093 thick 36 x 36 inches Edge depth - 4.0 inches Center depth – 6.0 inches

Formed deep drawn

Formed deep drawn

Mode shape – Fn = 148hz

Max Deflection under internal pressure

Maximum stress

Radiused edges

Flat welded

Welded ribs

Summary of results

DesignThin shell0.1 inch

NaturalFrequency

hz

Weightlbs

Pressurized

Deflectioninches

MaximumStress

psi

flatwelded

31 22.0 0.79 13,740

Deep drawn

Design #1

148 19.5 0.03 3,100

FlatRadiused

edges26 21.6 0.38 8,420

weldedribs

44 22.6 0.40 14,960

Study conclusions Deep drawn design

– Highest natural frequency best in shock and vibration environments

– Lightest weight– Smallest deflection under pressure– Lowest stress

Disadvantage – high tooling cost