Specimen gratings made from body art paper for in-plane moiré strain analysis

The Moiré method is a useful tool for in-plane full-field displacement measurement and strain analysis. This paper presents a convenient method for forming a grating to be used for geometry moiré and Fourier transform moiré and grid method (FTMGM) on the surface of polymeric specimens. In general, polymeric materials have low modulus of elasticity and can undergo large deformation during tests. These conditions put restrictions on selection of feasible gratings for moiré strain analysis of polymeric materials. In the current paper, a novel use of a grating made by special inkjet printer tattoo paper allows us to perform full-field strain analyses of polymeric materials by using the geometry moiré method and FTMGM. This grating has low modulus and can be bonded to the polymeric specimen surface in a very short time and can survive large deformations. These properties make it a practical grating for full-field strain analysis of polymeric material, using moiré methods. The grating making procedures are explained in detail. Two moiré applications are demonstrated, including geometry moiré and Fourier transform moiré methods for the in-plane deformation analysis of a U shape ethylene vinyl acetate specimen under tensile load.