Design Curves for Unvented Honeycomb Sandwich Structures Subject to In-Plane and Pressure Loads

Analysis methodology for the assessment of unvented honeycomb sandwich structures subject to in-plane and pressure loads

“…The stability equation, for buckling, simplifies as follows, with α matching the expression α=0.8191ϵ∗ for a clamped plate in. 3,6 Note the clamped plate assumption, w′(ρ=1)=0, is valid for infinite-core.…”

“…While in-plane loads tend to be unidirectional, a large batch of axisymmetric in-plane load models are significantly faster to run. An in-plane load correction factor was developed by Engelstad 6 so that results for axisymmetric models could be used for unidirectional in-plane load conditions.…”

“…The simplified infinite-core equations, namely (normal38)−(normal41), are considered, for which a change of variables from a′,P′ in ref. 3,4 to compression-adjusted parameters a∗,P∗ in 6 reduces the equations. A surrogate model matching the FEM from the parametric study is then created.…”

“…3 An approximate deflection which resembles the Bessel function is used to solve large deflections. 3,4,6 Namely, bell-shaped curves are used, where ρ=r/a is the normalized radius, and ωnormal0=wnormal0/h is the normalized center-plate deflection. The boundary conditions are: w(ρ=0)=wnormal0, w′(ρ=0)=0, w(ρ=1)=wnormal0δ, and w′(ρ=1)=−wnormal0μ/a where δ is a non-dimensional crack-tip deflection and μ is a non-dimensional crack-tip slope.…”

“…Goyal et al 4 considered a design curve for facesheet-core debonding, but without in-plane load. This paper further develops a new design curve by Engelstad 6 for facesheet-core debonding, under pressure and in-plane load. The design curve allows the determination of the critical flaw size given the geometric properties, material properties, and loading.…”