Development of a novel FRP composite with high-strength, large-deformation and tensile-behavior designable properties: Design concept and experimental program

Abstract

Conventional high-strength FRP materials suffer from brittle failure at low strains. This study proposes an innovative concept for achieving high-strength, large-deformation and tensile-behavior designable FRP composites. The proposed composite consists of FRP skins, inner cores and twisted knots to develop desired nonlinear behaviors. As the main load-carrying elements, FRP skins provide the ultimate strength and will squeeze inner cores under tensile loading. Inner cores are used to shape skins and determine the amounts of shaped skins to be unfolded by controlling core deformations. Core configurations are expected to be carefully designed and then realized by 3D printing technologies. Twisted knots are used to resist the opening stress at the core edges. Experimental results obtained from sixty tests validate this concept and identify the impacts of core configurations, i.e. brace thickness & angle, shell thickness, core span & height and core number, on the tensile behavior of the composite. A typical test failed in skin fracture developing a considerable stress (772 MPa or 78% FRP material strength) and strain (0.041 or 401% FRP ultimate strain). Test results also provide valuable data for further designing the proposed composite to feed increasingly updated demands.