Core-shell hybrid pre-preg tow for lightweight composite truss

Abstract

A robust pre-impregnated hybrid tow for manufacturing lightweight composite truss has been developed and characterized. The hybrid tow is in a core-shell structure where the core is epoxy pre-impregnated carbon fibers and shell is a protective braided jacket. The hybrid tow has good conformability which allows it to be used in braiding process for fabricating complex shape lattice structures. The mechanical properties of the hybrid tow are essential for modeling and designing of open lattice structures. The paper studies the experimentations on the hybrid tow to obtain mechanical properties including tensile modulus and strength, short beam shear modulus and strength, flexural modulus and strength, torsional modulus, and strength. The corresponding experiments contain tensile test, 3-point bending test, and torsion test. The least square method is employed to differentiate short beam shear and bending. Microscopic images of the cross-section were taken to study volume fraction via digital image processing. Mechanical properties and volume fractions of the tow were measured by the proposed experimental methods in this paper to provide insights of manufacture processes as well as multiscale modeling of open lattices.