Abstract: A process and apparatus for measuring mechanical properties of structural fibers. The process comprises the steps of suspending at least one fiber from a rigid fixture so that it may hang vertically therefrom; attaching a mass to the fiber, thereby placing the fiber in tension; guiding the mass in a frictionless manner to avoid extraneous damping so that only extensional motion is permitted; exciting the mass and the fiber with a longitudinally directed impulse to induce an amplitude of extensional vibration; generating output signals according to the impulse and the vibration response; and communicating computing means with the output signals. The computing means stores data for deriving certain material properties of the fiber based upon the output signals and computes the material properties.