Strain concentrations in woven fabric composites with holes

A strain mapping technique, namely digital photogrammetry, was used to investigate the tensile strain field of woven fabric composites in the presence of stress concentrations caused by geometrical defects consisting of circular or elliptical holes. Plain woven fabrics were used. The strain mapping technique clearly revealed the strain concentrations near the singularity. The strain concentrations are influenced by the tensile loading direction and the hole dimension relative to the size of the unit cell of the plain woven fabrics. A preliminary comparison of stresses approximately calculated from the strain field and theoretical stresses calculated from existing models such as Lekhnitskii’s model is also presented.