Dan DeFinis
Study of Multiple Laminates
Case 1:
[0,30,-45,60]s
Rectangle: .2x.1
Case 2:
[0,30,-45,60]s
Rectangle: .1x.2
Case 3:
[90,60,-45,30]s
Rectangle: .2x.1
Case 4:
[90,60,-45,30]s
Rectangle: .1x.2
Summary and Conclusion:
Due to the nature of the layup used in these cases, the laminate becomes disproportionately stronger in
one direction. Depending on the alignment of the fibers to the long axis of the rectangle the deflection
in the center can be roughly double with a weaker laminate compared to a stronger one. This is
demonstrated initially with Case 1 and 2 which both have the same layup of: [0,30,-45,60]s. The only
difference is that Case 2 is rotated 90 degrees. This results in a deflection of .0493 instead of .1043. By
adjusting the layup as seen in case 3 and 4 to [90,60,-45,30]s, which replaces the 0 degree sheets with
90 degree sheets, and reverses the order of the 30 and 60 degree sheets found in Cases 1 and 2, the
opposite effect is achieved. Case 3 and Case 4 show the same deflection as Case 2 and Case 1,
respectively.
Observation of these four cases demonstrates how the layup can be changed depending on the
intended use and loading of the laminate. Careful adjustment of the layup structure can produce equal
deflections in differently oriented composites.