A
test is performed to measure elastic modulus of hull laminate with
respect to orientation angle in order to aid in identifying internal
stringer alignment positions and spacing. The stringers are in
excess of existing design bulkheads and frames which concentrate on
rig and deck support and load transfer from keelson to shell in high
stress points of keel mount. Attention to large flat areas in bow
and after of keel on hull bottom are under special attention.
Measurements
are made on samples of laminate structure that are cut from a hull
sample that matches actual. No attempt was made to further refine
the laminate structure beyond two 3mm marine ply sheets constructed
of 3 each plys having 0/90/0 orientation. The orientation angle is
measured from the horizontal baseline set to 0 degree with the boat
upside down. Two samples are aligned with the cold molded strips at
53.5 degree and 128.5 degree. Strips are approximately 28.5mm x 3mm
cross section and 133mm between supports on a loading apparatus. The
loader applies a force to the middle of the sample suspended on
simple supports. Deflection is measured at the center and loading is
up to 50lbf. Two samples were made at each angle of 0, 90, 53.5,
128.5 deg. Unfortunately samples were not prepared for 128 deg to
180 deg. A plot of orientation vs modulus is made for 360 degrees
and averages E for each common pair. Samples
I and J exhibited a run away creep at full test load and were allowed
to go to failure.
Results as follows prior to refining data and
modifying hull construction design elements.
| Sample | Orientation | E | |
| # | angle | psi | Mpa |
| A | 90 | 606,918 | 4185 |
| B | 90 | 535,913 | 3695 |
| C | 0 | 609,315 | 4201 |
| D | 0 | 582,125 | 4014 |
| E | 22.5 | 577,332 | 3981 |
| F | 67.5 | 400,534 | 2762 |
| G | 53.5 | 350,833 | 2419 |
| H | 53.5 | 365,887 | 2523 |
| I | 128.5 | 465,069 | 3207 |
| J |
128.5 |
469,235 |
3235 |
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