Energy absorbing composite structures

A composite article comprising at least three components and incorporating (1) a ductile, load-bearing tubular element bonded to a second component, the ductility of the tubular element being such that the tubular element deforms plastically at a part intermediate its ends when subjected to an axial tensile stress which is lower than the ultimate tensile strength of the element, the tubular element having deformation characteristics which cause its wall to contract toward the longitudinal axis thereof, (2) an inner member positioned at least partially within at least part of the tubular element which is engaged by the tubular element as it contracts and resists contraction to cause absorption of energy.

A composite article resistive to tensile stress, said article comprising at least two components and incorporating, as one component, a ductile, load-bearing tubular element reinforcement means having its external wall inter facially bonded to the other of said components and its axis substantially parallel to the expected direction of tensile stress in said article, the tubular element being such that the tubular element deforms plastically at a location intermediate its ends when subjected to axis tensile stress which is less than the ultimate tensile strength of the material of the element, the deformation characteristics of said tubular element being such that when subjected to tensile stress it debonds from the other component as the tubular element contracts towards its longitudinal axis whereby a proportion of the tensile stress to which the article is subject is transferred from one part to other parts of the article by the element as it debonds.

A composite article resistive to tensile stress comprising a matrix incorporating as reinforcement means therein at least one load-bearing tubular element of ductile material having its longitudinal axis substantially parallel to the expected direction of tensile stress in the article, said tubular element being contained at least partially in and bonded to the matrix material of the matrix, the ductility of the tubular element being such that the element deforms plastically at a part intermediate its ends when subjected to an axial tensile stress less than the ultimate tensile strength of the tubular element, said ductile material of the tubular element having deformation characteristics such that under tensile stress conditions the wall of said intermediate part of the tubular element contracts towards its longitudinal axis and debonds from the matrix material, the deformation of the tubular element resulting in transfer of tensile stresses to other parts of said matrix while at the same time absorbing energy.

An energy absorbing composite structure resistive to tensile stress including, as the primary tensile load-bearing element, a ductile high strength steel tubular element embedded in and interfacially bonded to a rubbery plastic matrix, the tubular element having its longitudinal axis substantially parallel to the expected direction of tensile stress in the composite structure and, when subjected to tensile stress, the element debonds progressively from the surrounding matrix while contracting towards its longitudinal axis, thus its resistance to debonding and contraction causing absorption of energy up to the ultimate tensile strength of the composite structure.