Abstract

The natural frequency is studied for composite material strengthen by short fibers and long fibers, with the effect of crack orientation for different aspect ratio of plate and the type of plate fixing where simply supported in all edges. Two methods are used to find the natural frequency of composite plate: First method is an experimental method by applied a time varied load and admeasure the natural frequency of the plate. Second method is a finite element solution using ANSYS (ver. 14) program. A comparison made between the three methods and the error percentage is not exceeds of 8.5%. The amount of decreasing in natural frequency increases when the crack inclined with an angle than that without inclination angle, because the effect of the crack distributed on the both sides of the plate will be a bigger effect.