Analysis of a repaired composite structure

A method for analyzing a repaired composite structure composed of a plurality of original plies and additional repair plies at an area of repair, each ply including a top surface, a midplane and a bottom surface, the method comprising:

• performing a finite element analysis of a finite element model of the repaired composite structure composed of a plurality of finite elements for the plurality of original plies and the additional repair plies, the finite element analysis being performed to determine in-situ strains at the midplanes of and thereby midplane in-situ strains at the plurality of original plies and the additional repair plies;
• determining in-situ strains at the top surface and the bottom surface of and thereby surface in-situ strains at the plurality of original plies and the additional repair plies from the midplane in-situ strains;
• determining a margin of safety for the repaired composite structure from in-situ strain data selected from the midplane in-situ strains and surface in-situ strains;
• and
• outputting the margin of safety from which to accept or reject the repaired composite structure, or an indication to accept or reject the repaired composite structure based on the margin of safety.

A computer readable medium for analyzing a repaired composite structure composed of a plurality of original plies and additional repair plies at an area of repair, each ply including a top surface, a midplane and a bottom surface, the computer-readable storage medium being non-transitory and having computer-readable program code portions stored therein that, in response to execution by a processor, cause an apparatus to at least:

• perform a finite element analysis of a finite element model of the repaired composite structure composed of a plurality of finite elements for the plurality of original plies and the additional repair plies, the finite element analysis being performed to determine in-situ strains at the midplanes of and thereby midplane in-situ strains at the plurality of original plies and the additional repair plies;
• determine in-situ strains at the top surface and the bottom surface of and thereby surface in-situ strains at the plurality of original plies and the additional repair plies from the midplane in-situ strains;
• determine a margin of safety for the repaired composite structure from in-situ strain data selected from the midplane in-situ strains and surface in-situ strains;
• and
• output the margin of safety from which to accept or reject the repaired composite structure, or an indication to accept or reject the repaired composite structure based on the margin of safety.