Problem description
The model is a single, flat plate, 328 mm long, 28 mm wide, and 3 mm thick, built into a rigid wheel of 150 mm radius, spinning about its axis. Two versions of the problem are studied. In “Case A” the plate is mounted so that its first vibration mode is in the plane containing the axis of the wheel. Thus, the line of action of the centrifugal load does not change as the blade undergoes small vibrations; hence, the load stiffness effect does not participate in this mode. In “Case B” the plate is mounted so that its first vibration mode is in a plane at right angles to the axis of rotation of the wheel. Thus, the load stiffness effect is important in this mode. Since the plate is relatively long compared to the radius of the wheel, the load stiffness effect is significant: the first mode frequency is substantially lower in Case B than it is in Case A.
Several different element types are used (beams, shells, three-dimensional solid elements). In each case a “reasonable” mesh is chosen—typically six elements along the plate. Since we are comparing only the lowest mode frequency, rather coarse meshing should be adequate.
The plate is made of steel, with Young's modulus 217 GPa and a density of 7850 kg/m3.