Slide 2 Hygrothermal behavior of composite laminates Composite
materials can absorb moisture and expand in the same way that they
expand due to temperature. We can use the same kind of analysis to
deal with stresses that arise from both. In this course we will
focus on thermal behavior. The effect of temperatures on composite
laminates is more pronounced than on metals because of large
disparity in coefficient of thermal expansion. Slide 3 Effect of
mismatch Slide 4 Thermal deformations If ply can expand or contract
due to hygrothermal effects, only strains, but no stresses. Stress
free expansion strain in a unidirectional layer (Fig. 3.2) Slide 5
Strains and stresses Free strains Hookes law when total strains are
different from free strains. Slide 6 Interaction between plies
0/90/45 laminate Constraining effect of adjacent laminates Slide 7
(0/90) s laminate Stress-free expansion of layers Constrained
deformation Slide 8 Residual strains Slide 9 Residual stresses
Slide 10 Thermal loads If a laminate is subjected to temperature
change without any loads then the stress and moment resultants
should be zero. Substituting from previous slide for in-plane
equation for symmetric laminate Loads needed to produce same
strains without temperatures Slide 11 Thermal loads for a single
isotropic layer Slide 12 With bending Slide 13 With Tsai-Pagano
Material constants Thermal loads Thermal material constants Any
checks that we can apply?