Parameters
Load Condition
Load & Span
Span L1000 mm
Width b500 mm
Load intensity q / P5.0 kPa
Face Sheet
Face thickness t_f1.5 mm
Face modulus E_f70 GPa
Face yield stress σ_y270 MPa
Core
Core thickness t_c25 mm
Core modulus E_c0.10 GPa
Core shear modulus G_c0.050 GPa
Core shear strength τ_y1.50 MPa
—
Face Stress σ [MPa]
—
Core Shear τ [MPa]
—
Deflection δ [mm]
—
Buckling P_cr [kN]
—
Wrinkling σ_w [MPa]
—
Bending Stiffness D [N·m]
Stress vs. Allowable
Deflection vs. Span Ratio
Governing Equations
Equivalent bending stiffness:
$$D = \frac{E_f t_f d^2}{2} + \frac{E_f t_f^3}{6} + \frac{E_c t_c^3}{12}$$where $d = t_c + t_f$ (distance between face centroids)
Face stress: $\sigma_f = \dfrac{M \cdot e}{D}$, $e = d/2$
Core shear stress: $\tau_c = \dfrac{V}{d \cdot b}$
Mid-span deflection (UDL, SS, with shear):
$$\delta = \frac{5qL^4}{384D} + \frac{qL^2}{8 A_c G_c}$$Wrinkling stress: $\sigma_w \approx 0.5(E_f E_c G_c)^{1/3}$
CAE Note: When modelling in Abaqus or Nastran, the sandwich can be represented as equivalent single-layer shell elements using homogenized properties, or as layered composite shells. Core shear moduli are typically obtained via homogenization of the cellular geometry.