MODAL CHARACTERISTICS OF STRUCTURAL PORTAL FRAMES MADE OF MECHANICALLY JOINED PULTRUDED FLAT HYBRID COMPOSITES

The primary objective of this investigation is to analyze and compare the dynamic behavior of framed structures made of orthotropic material s manufactured by the pultrusion process. Pultruded flat beams made of glass/epoxy, graphite/epoxy and various lay-up combinations of hybrid glass-graphile/epoxy are used to produce high-modulus and lightweight , L-shaped, portal frame and other composite material structures. The dynamic properties of the decoupled and mechanically fastened coupled structures were obtained by the experimental modal analysis technique. The structural properties identification process for each of the beam and lumped systems consists of generating the frequency response func tions (FRF), estimation of natural frequencies, damping, and the assoc iated mode shapes. A measurement chain comprising a dual-channel dynam ic signal analyzer, corresponding instruments and a modal analysis sof tware package has been used for identifying the modal parameters. The experimental results demonstrate the applicability and dynamic superio rity of structures made with pultruded hybrid composite materials.