Laminated structural article with constituent elements having inherent fracture arrestment capability

A heterogeneous sheet-like material having horizontally coplanar portions of differing modulus of elasticity for fabricating therefrom a composite structural laminate having high crack propagation arrestment characteristics comprising in combination:

• a plurality of basal tracts and a plurality of fracture barrier tracts in horizontally coplanar edge-to-edge arrangement therewith forming a heterogeneous composite sheet-like material.
• the basal tracts adapted to carry the major portion of a load applied to said sheet and the barrier tracts being narrower than said basal tracts and disposed marginally to said basal tracts and acting to arrest propagation of a crack developing in one of said basal tracts and extending to an adjacent barrier tract,
• each of said tracts being a substantially flat strip containing a plurality of generally parallel reinforcement fibers embedded in a fracture tough resinous polymer matrix,
• the basal and marginal barrier tracts being alternately disposed in a common horizontal plane and integrally united along their adjoining edges,
• the modulus of elasticity of the basal tract fibers being greater than nine million pounds per square inch, and
• said basal tracts possessing a higher value of modulus of elasticity in the direction parallel thereto than that of the marginal barrier tracts in the same direction.

A multiply heterogeneous composite structural laminate having high crack propagation arrestment characteristics formed from a plurality of plies one or more of which contains horizontally coplanar portions of differing modulus of elasticity, comprising:

• at least one fracture barrier containing primary ply having a plurality of generally parallel high modulus fibers embedded in a polymer matrix and formed from a plurality of substantially flat, strip-like basal tracts and fracture barrier tracts in horizontally coplanar edge-to-edge arrangement therewith;
• the basal tracts adapted to carry the major portion of a load applied to said laminate and the barrier tracts being narrower than the basal tracts and disposed marginally to said basal tracts and acting to arrest propagation of a crack developing in one of said basal tracts and extending to an adjacent barrier tract;
• the basal and marginal barrier tracts being alternately disposed in their ply in a common horizontal plane and integrally united along their adjoining edges;
• said basal tracts possessing a higher value of modulus of elasticity in the direction parallel thereto than that of the marginally adjacent barrier tracts in the same direction;
• and
• the modulus of elasticity of the basal tract fibers being greater than nine million pounds per square inch;
• and
• at least one load distributing secondary ply of generally parallel high modulus reinforcing fibers embedded in a resinous polymer matrix and united in face-to-face relationship to said fracture barrier containing ply, and
• said load distributing secondary ply having load-transmitting portions whose modulus of elasticity as measured in the direction of the basal tracts of said first mentioned ply is less than said basal tracts and structurally connect across basal tracts of an adjacent ply for transmitting of loadings therebetween.