Dynamic behaviour of composites reinforced with needles from fir trees

In this paper we build some composite materials reinforced with needles from fir trees. order to the samples, have firstly created strips in way: put pines, continuously, on a sheet of where apply thin layer resin (we used epoxy and polyester ones). We made 10 glued them together by using same synthetic resins (epoxy polyester). end obtained composites trees sheet, matrix is resins. From plate, cut samples study their free vibrations. placed an accelerometer at about mm edge clamped several lengths. The connected signal conditioner NEXUS which also data acquisition system SPIDER 8. notebook through USB port. vibrations, determined: eigenfrequency, damping factor per unit mass, length, dynamic stiffness, Young modulus loss factor.