Aerospace Engineering Department
BS in Aerospace Engineering
Several vibration and tensile tests were conducted for four natural fiber hemp composites in order to observe its behavior and acquire the material properties of hemp. Two plates were made on the Cal Poly press table, while the other two plates were made on the Cal Poly vacuum table. All four plates are made of 100% hemp under three different types of weave. The first plate is called CTPT-12, has a thickness of 0.053 inches, and was made on the press table. The second plate is called CTL4 with a thickness of 0.152 inches and made on the press table. The third plate is called HL-10 with a thickness of 0.2145 inches, and made on the vacuum table. The fourth plate is called CTPT-12 with a thickness of 0.264 inches and made on the vacuum table. A second portion of the project was performed to further study the behavior of hemp composites. Several hemp plates with dimensions of 1.5 inch by 6 inch were made. These plates were manufactured in the vacuum table with four layers of CTPT-12 material and a 1 inch by 1.5 inch delamination. The results indicated a maximum stress of 118280 psi and a maximum displacement of 2 inches from end to end. Each plate was made with organic epoxy under a curing cycle that lasted about a day at a temperature of 150° F. Each plate had a different material property due to its different weave and manufacturing process.The plate that resisted the highest force and the highest Young’s Modulus was the fourth plate with 704 lbf and 937 ksi, respectively. Plate 2 resisted the least with a force of 278 lbf and a Young’s Modulus of 554 ksi. Plate 3 had the lowest Young’s Modulus of 513 ksi with a force of 379 lbf. The vibration sweep ranged from 5 Hz to 1000 Hz with varying control amplitude throughout the run. The results indicated that there were significant differences between the four plates. The first plate had the highest natural frequency of 69.93 Hz at a distance of 4 inches from the surface of the aluminum blocks holding the plate for the vibration test. Plate 2 had the lowest frequency of 5 Hz when the accelerometer was placed 8 inches from the surface of the aluminum blocks. The experiment concluded that the experimental values and the finite element analysis had some similar results.