# Panel Metallic Specialization

## Panel Metallic Structural Property

In addition to the common data names for panels, the Panel_metallic configuration has two other data names, Thickness and Material.

These attributes are meant to be constant overall in a panel. Properties are not meant to vary across elements inside the panel using these attributes. Using the Absorb FE option during Auto DDP, the panel’s central element will be used as a reference.
• Thickness will be copied from central element thickness
• Material will point to the central element’s material entity

## Panel Metallic Failure

The Panel_metallic configuration is shipped with a DLL method called Panel_FailureMode. It computes possible failure modes for a metallic panel. The method requires shell element forces to be available in the result file. It assumes a valid panel with constant thickness and retrieves thickness information from its structural property. Panel thickness is used to recompute element stress XX, YY, XY. Similarly, the structural property’s material is used to extract tensile/compressive and shear allowable. Method evaluates margin of safety as MS= Allowable/Stress -1 for the three directions. For directions one and two (XX and YY) depending on the stress state either tensile or compressive allowable is used. For shear (XY) absolute stress value is considered in the margin of safety formula.

## Panel_FailureMode_ShearBuckling

A fourth failure mode is computed as shear buckling failure of curved panel. In the latter, the highest shear force seen by all elements in the design point is considered. Shear buckling is a ratio of stress with Fscrit = $\pi$ 2KcE/(12*(1- $v$ 2)*(t/b)2 where Kc=Rs+0.2*W2/(R*T).

Rs is available as structural property metadata Radius_shear_constant and the default is 5.35.