4 Test Results
All four test articles were bent to a tip deflection of D = 1.5 inches without causing any noticeable damage.
All four test articles wxhibited linear elastic deformation up to attest displacement of D = 1.5 inches and a tip force of P = 1600 pounds.
Force versus displacement plots of the four test articles are shown in Figure 2.
The test articles were significantly stiffer and stronger than anticipated. We believe that the extraordinary strength and stiffness of the retrofitted test articles is due to excellent bonding between the Urethane and the Aluminum tube, lateral confinement of the Urethane by the Aluminum, and very high Poisson ration (greater than 0.45) for the Urethane.