OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 3 2023 Fig. 3. Vibration testing: a – block daigram of free vibration; b – free vibration testing a b cantilever beam with dimensions of 160×10×3.5 mm. The corresponding damping factors were calculated using the fixed circle method, and the equation used to calculate the damping factors is shown below. 2 2 2 1 2 1 0 2 1 . 2 tan tan 2 2 ω ω ζ = α α ω ω +ω Results and Discussion Tensile Test The results of the tensile test of the dumbbell-shaped specimens (fig. 4) indicate that the mechanical properties of the layered CM increase when fibers are added to the matrix. The ultimate strength of NR is 62 MPa, and when 20 % of Munya PC fibers are added to the resin, the ultimate strength increases to 85 MPa. The addition of 20 % SRC fiber to the epoxy resin increases the ultimate strength to 123 MPa. The addition of 20 % UDC fiber to the epoxy resin also increases the tensile strength to 170 MPa. The highest ultimate strength of UDC composites is 170 MPa, which is 28 % more than the ultimate strength of SRC composites, 50 % more than the strength of PC composites, and 63 % more than the strength of NR. The addition of Munya fiber to the polymer matrix increases the permanent deformation of the composite polymer based on the Munya fiber. The ultimate strength of 85 MPa was in the case of PC, which is 28 % greater than the ultimate strength of NR.
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