Bulk Data Entry Controls the alternate method for the creation of CMS superelements using the AMSES eigensolver.

Parameter Values Description

Default = Comment 2

Unlike the conventional approach, this formulation does not separately calculate the static and dynamic modes using the linear sparse solver and eigenvalue solver, respectively. The static and dynamic modes are combined together to project the physical modal space into the CMS space, allowing for the efficient creation of superelements. This projection also applies to the material damping and fluid structure interface matrices with minimal extra computational cost, in contrast to the conventional approach wherein, this is done outside the eigensolver as a computationally intensive process.
The new formulation for the creation of CMS superelements using the AMSES eigensolver is activated.
The new formulation is not active, and the old method is used.


  1. The new formulation is especially effective, and considerable speedup may be achieved over the conventional approach, when there are a lot of ASET degrees of freedom in the model (for example, thousands of ASETs).
  2. The new formulation is only supported for CMS superelement creation in Craig-Bampton form (METHOD=CBN on the CMSMETH Bulk Entry), General Modal Formulation (METHOD=GM on CMSMETH Bulk Entry), and Flexbody Generation (METHOD=CB) in multibody dynamics. For these cases, the new formulation is turned ON by default. For all other cases, the old method is the default (for GM method, the new formulation is turned on by default, only if ASET entry is present).
  3. When METHOD=GUYAN is used in conjunction with AMSES, then the new formulation is turned ON by default. Additionally, GUYAN will be converted to CBN method with an upper bound of 0.001 Hz.