Shear modulus loss as damage indicator of structural integrity in bonded joints

Damage in single lap joints under shear load was assessed. Specimens were tested in accordance with ASTM D1002-10(2019). Controls were taken on adhesive and surface preparation, adhesive thickness, and load-specimen alignment. Digital Image Correlation was used to measure stresses over the adhesive, and shear modulus variation and percent of damage were assessed. Results show shear modulus losses against shear stress. Finally, early damage evolution was determined up to 10% of the shear load rate and later, increasing up to 70%-96%.