Tabular data

Create a tabular data report of the midspan displacements. Use the node set Midspan to create the appropriate display group and the frame selector to choose the final frame. The contents of the report are shown below. 

Field Output Report

Source 1
---------

   ODB: NlSkewPlate.odb
   Step: Apply pressure
   Frame: Increment      6: Step Time =    1.000

Loc 1 : Nodal values from source 1

Output sorted by column "Node Label".

Field Output reported at nodes for part: PLATE-1

            Node            U.U1            U.U2            U.U3
           Label          @Loc 1          @Loc 1          @Loc 1
-----------------------------------------------------------------
               1    -2.68697E-03    -747.394E-06    -49.4696E-03
               2    -2.27869E-03    -806.331E-06    -45.4817E-03
               7    -2.57405E-03    -759.298E-06    -48.5985E-03
               8    -2.49085E-03    -775.165E-06    -47.7038E-03
               9     -2.4038E-03    -793.355E-06     -46.533E-03
              66    -2.62603E-03    -750.246E-06    -49.0086E-03
              70    -2.53886E-03    -762.497E-06    -48.1876E-03
              73    -2.45757E-03    -778.207E-06     -47.144E-03
              76    -2.36229E-03    -794.069E-06    -45.9613E-03

  Minimum           -2.68697E-03    -806.331E-06    -49.4696E-03

         At Node               1               2               1
  Maximum           -2.27869E-03    -747.394E-06    -45.4817E-03

         At Node               2               1               2

Compare these with the displacements from the linear analysis in Using Shell Elements. The maximum displacement at the midspan in this simulation is about 9% less than that predicted from the linear analysis. Including the nonlinear geometric effects in the simulation reduces the vertical deflection (U3) of the midspan of the plate.

Another difference between the two analyses is that in the nonlinear simulation there are nonzero deflections in the 1- and 2-directions. What effects make the in-plane displacements, U1 and U2, nonzero in the nonlinear analysis? Why is the vertical deflection of the plate less in the nonlinear analysis?

The plate deforms into a curved shape: a geometry change that is taken into account in the nonlinear simulation. As a consequence, membrane effects cause some of the load to be carried by membrane action rather than by bending alone. This makes the plate stiffer. In addition, the pressure loading, which is always normal to the plate's surface, starts to have a component in the 1- and 2-directions as the plate deforms. The nonlinear analysis includes the effects of this stiffening and the changing direction of the pressure. Neither of these effects is included in the linear simulation.

The differences between the linear and nonlinear simulations are sufficiently large to indicate that a linear simulation is not adequate for this plate under this particular loading condition.