Composites with interphases and methods of making the same

A method of making a composite incorporating a fiber, a matrix and an interphase comprising the steps of:

• (a) storing a nodal model of a composite in an analog or digital computer, said model comprising
• (1) a plurality of notional spaced-apart nodes representing points within a notional fiber of finite aspect ratio surrounded by a notional interphase extending in a notional matrix and
• (2) functions representing physical properties of said notional fiber, matrix and interphase as interrrelations between displacement of each said node relative to each adjacent node and strain energy, said functions defining said interrelations so that said strain energy includes components representative of shearing stress of said matrix material and said interphase,
• (b) inputting at least one notional deformation into said computer;
• (c) actuating said computer to apply said notional deformation such that said functions indicate that said notional composite would fracture under said notional deformation, and determining at least one property of said composite from said functions;
• (d) varying the value of at least one said physical property of said fiber, matrix or interphase in said functions and repeating said inputting and actuating steps for each such variation whereby on each repetition said computer-operated model indicates the property of said composite for different values of said varied physical property;
• (e) determining an optimum value for said varied physical property dependent upon the physical properties of said composite indicated by said model for said different values, and
• (f) forming at least one real composite having a real fiber, real matrix and real interphase with said optimum property.