Software Forms > Sizing Form > Dimensions Tab > Grid Stiffened Panel Family

Grid Stiffened Panel Family

t_tf = Top face thickness (material assignment)
t₀ = 0° web thickness (material assignment)
t₉₀ = 90° web thickness
t_q = Angle web thickness
t_bf = Bottom face thickness (material assignment)
S₀ = 0° web spacing
θ = Web angle
h₀ = Height of 0° web
h_q = Height of angle web
h₉₀ = Height of 90° web
S₉₀ = 90° web spacing
S_q = Angle web spacing

Concept	t_tf	t₀	t₉₀	t_q	t_bf	S₀	θ	h₀	h_q	h₉₀	S₉₀	S_q
0Grid
90Grid
OrthoGrid
WaffleGrid
IsoGrid							60°
AngleGrid
GeneralGrid
OrthoGrid Sandwich
AngleGrid Sandwich

The materials for all webs (0°, 90°, angle) are restricted to be the same. HyperLaminates can be used to model different layups in each web.

L2 = 90° web
L3 = 0° web
L4 = Angle web

The AngleGrid concept and the Isogrid concept are very similar. The only difference is that the AngleGrid allows the user to specify the angle variable on the Variables tab. If the IsoGrid concept is chosen, then the software will ignore the angle sizing variable on the Variables tab and will use an angle of 60 degrees. Assuming the ribs are all the same height and thickness, this means that the panel will have the same strength in the 0° and 90° directions, hence the name "Iso" grid.

Options

Multiaxial sandwiches Specifies concepts with both top and bottom facesheets.
Link web thicknesses All resultant web thicknesses will be the same. Group variable thickness bounds for the 90° and angle webs will be overridden by the 0° web thickness bounds.
Link web heights All resultant web heights will be the same. Group variable height bounds for the 90° and angle webs will be overridden by the 0° web height bounds.
Link facesheet materials For sandwich concepts, apply the top facesheet materials to the bottom facesheet. Bottom facesheet material selections are ignored. The resulting materials will be the same.
Link material for facesheets and web For all concepts, link all material selections to the top facesheet. Web and bottom material selections are ignored. The resultant materials will be equivalent.
Link layups/thicknesses for facesheets and 0° web (requires material linking) For continuous materials with material linking, requires that the thicknesses in both facesheets and the 0° web are equal.

Fillets and Lightening Holes

Several constants are available to model the additional weight of the fillets and weight reductions due to lightening holes. These constants are entered on the Options tab of the Sizing form.

Fillets are necessary at the intersection of the facesheet and stiffener webs as well as at the intersection of the stiffener webs. The top of the figure below shows the fillet at the interface of the 0° web to the facesheet. Shown in the bottom-right side of the figure is a large fillet at the intersection of the 0° and 90° webs.

Using the radius of the fillet, the volume of the fillet is found by assuming a simplified geometry, as shown below. The volume is then converted into mass using the material density.

The first figure also depicts a lightening hole at the intersection of the stiffener webs. The weight reduction from this hole is computed. The maximum diameter of the lightening hole is limited to ensure that the minimum wall thickness in the region is at least equal to the average of the t₀ and t₉₀ wall thicknesses.