Here's a few useful equations that I derived in one of my papers for
Flexcon a few years back.

Location of Neutral Axis (in) = Sum (Area of Layer x Modulus of Layer x
Distance of Layer from Origin) / Sum (Area of Layer x Modulus of Layer)

Composite Moment of Inertia (in^4) = Sum (((Width of Layer x (Modulus of
Layer / Modulus of Stiffest Layer) x Thickness of Layer ^ 3) / 12) +
(Width of Layer x (Modulus of Layer / Modulus of Stiffest Layer) x
Thickness of Layer x Distance of Layer from Neutral Axis ^ 2))

Composite Thermal Strain (in/in) = Change in Temp. x Sum (Layer Modulus
x Area of Layer x CTE of Layer) / Sum (Layer Modulus x Area of Layer)

Thermal Bending Moment (in-lb) = Sum (Layer Modulus x Area of Layer x (
Composite Thermal Strain - (Change in Temp. x CTE of Layer) ) x Distance
of Layer from Neutral Axis)

Thermal Bend Radius (in) = (Modulus of Stiffest Layer x Composite Moment
of Inertia) / Thermal Bending Moment

These equations are implemented in software posted at:
http://www.geocities.com/CapeCanaveral/Launchpad/9641/program/program.html

Andy Magee
Flex Guru - Consulting
[log in to unmask]
(937) 435-3629

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