Pressure

The Pressure PropertyManager applies uniform or nonuniform (variable) pressure to faces for use in structural (static, frequency, buckling, nonlinear and dynamic) studies. Uniform pressure is applied in the specified direction with uniform distribution to all selected faces. Pressure can be applied normal to the selected faces or it can be applied in some other direction. For example, hydrostatic pressure is normal to faces, while the snow on a sloped roof applies a vertical pressure and a wind blowing horizontally applies a horizontal pressure.

The equivalent force magnitude generated by pressure is equal to the pressure value times the area of the face. However, the net equivalent force depends on the geometry of the face and the direction of the pressure. For example, the reaction force resulting from applying a hydrostatic pressure on a full cylindrical face is zero due to symmetry.

Nonuniform pressure is described by a multiplier and a pressure distribution. The pressure distribution is described by the coefficients of a second-order polynomial in terms of a reference coordinate system.

The coordinate system should be oriented such that the distribution on the target face varies with respect to the x and y coordinates only.

• Pressure Type. Sets the pressure type.

• Normal to selected face. Applies pressure in the direction normal to each face or shell edge you select. In the case of shell edges, the pressure is applied normal to the narrow face (across the thickness) of the shell.

• Use reference geometry. Applies pressure in the direction specified by the reference entity you select.

In an assembly, you can use reference geometry from the assembly or the components (parts and sub-assemblies) of the assembly.

• Faces, Edges for Pressure . Select faces of solid models or edges and faces of shell models to apply the pressure.

• Face, Edge, Plane, Axis for Direction . Select a reference entity to specify the direction of pressure. This option appears only if you select Use reference geometry.

• If you select a planar face or a reference plane, you can specify pressure Along Plane Dir 1 , Along Plane Dir 2 , or Normal to Plane .

• If you select a cylindrical face or a reference axis, you can specify pressure in the Radial , Circumferential , or Axial direction.

• If you select an edge, you can specify pressure along the edge . To reverse the direction of pressure, enter a negative value.

• Pressure Value. Sets the Units and the Pressure value .

• Variation with Time. For linear and nonlinear dynamic studies, you can define a time-dependent pressure.

• Nonuniform Distribution. If checked, allows you to specify options for nonuniform pressure.

• Select a Coordinate System . Select a coordinate system to define the nonuniform pressure.

• Equation Coefficients. Sets the polynomial coefficients which describe the spatial variation of the pressure in the selected coordinate system. The coefficients should be specified based on the units of X and Y as shown in the following table:

• Symbol Settings. Sets the color and size of pressure symbols.

• Edit color. Select a color for the pressure symbols from the color palette.

• Symbol size . Use the spin arrows to change the size of the pressure symbols.

• Show preview. Turns on/off the display of pressure symbols.

NOTES:

The nonuniform pressure distribution is defined by a reference coordinate system and the associated coefficients of a second-order polynomial.

p(X,Y) = V* (A + B*X  +  C*Y + D*X*Y  + E*X^2 +  F*Y^2)

Where:

p(X,Y) = magnitude of pressure applied at a point with coordinates x and y

V is the value specified in the Pressure value field.

X, Y  = coordinates of the point relative to the selected coordinate system. The coordinate values depend on the selected Units system.

A, B, C, D, E, and F are polynomial coefficients. Their values depend on the selected Units system.

* indicates multiplication