The elastic properties of core affect mechanical properties and deformation behaviours of the
lightweight sandwich panel. The objective of the present paper is to estimate experimentally
Young’s and shear moduli of a core in internally structured boned (ISB) panel with woven metal
as inner structures using the deflection theory of sandwich beam considered core stiffness. Three
points bending experiments were performed to obtain force-deflection curves of the designed ISB
panel in each material direction. The elastic and shear moduli of the core in each material
direction were estimated from slopes and intercepts of relationships between compliance per the
span length and square of the span length, respectively. The results of the estimation showed that
the fabric technology of the woven metal affects the variation of the elastic properties in the core.
Through the comparison of shear moduli and force-deflection curves of the proposed method and
those without considering the core stiffness, it was shown that the core stiffness should be
considered to estimate properly the Young’s and shear moduli of ISB panels. Finally, the
contribution ratio of bending and shear deflections of ISB panels to the total deflection was
quantitatively examined.