Influence of the stacking sequence on the through-thickness Young’s moduli of fibrous composite laminates measured by nanoindentation

Previous approaches to measure the through-thickness Young’s modulus of a composite laminate often employed complicated specimens and test procedures, so very few through-thickness Young’s moduli were reported. An efficient spherical nanoindentation approach was developed to measure the through-thickness Young’s moduli of a woven fibric glass-fiber composite laminate. In this paper, the same approach is extended to the modulus measurement of four carbon fiber/epoxy IM7/937-7 laminates with complicated stacking sequences. The measured through-thickness Young’s moduli were consistent with the transverse Young’s modulus of the same composite system. Results show that the stacking sequences have little influence on the through-thickness Young’s moduli, which could be explained by classical lamination theory for a thin composite laminate.