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# 8.26 Surfaces - Basic Strains

To control the graphical display of surface strains, select Surfaces → Strains in the Results navigator. Table 4.26 shows the basic strains of surfaces in numerical form.

The table shows the strains sorted by surfaces. The results are listed in reference to the grid points of each surface.

Grid Point

The numbers of the grid points are listed by surface. For more information about grid points, see Chapter 8.13.

Grid Point Coordinates

Table columns B to D show the coordinates of grid points in the global coordinate system XYZ.

Basic Strains

The strains are related to the directions of the local surface axes. When you analyze curved surfaces, they refer to the axes of the finite elements (see Figure 8.41).

The basic strains have the following meanings:

 εx,+ Strain in the direction of the local axis x on the positive side of the surface (i.e. side in direction of positive surface axis z) where d: thickness of surface εy,+ Strain in the direction of the local axis y on the positive side of the surface (i.e. side in direction of positive surface axis z) γxy,+ Related rotation on the positive side of the surface εx,− Strain in the direction of the axis x on the negative side of the surface εy,− Strain in the direction of the axis y on the negative side of the surface γxy,− Related rotation on the negative side of the surface