Compute effective mass for the supplied mode shapes.
emf = effmass(shp,fem,sub)
[emf,cmass] = effmass(shp,fem,sub,'norot','silent')
EFFMASS computes the effective mass fractions for the supplied imat_shp SHP. EFFMASS assumes that the shape coefficients in SHP are in the same displacement coordinate system(s) as the nodes in FEM, and that the mass matrix is consistent with these coordinate systems. It will compute the effective mass fractions and display both the computed overall mass matrix and the effective mass fractions.
FEM is an imat_fem containing the nodes and coordinate systems for the ASET nodes.
SUB is a structure containing the substructure. It must have at minimum the fields
.mass - NDOFxNDOF matrix containing the ASET mass matrix.
.aset - imat_ctrace of length NDOF containing the ASET degrees of freedom.
Two optional input arguments are supported. Passing in the string 'norot' will cause EFFMASS to compute only the translational effective masses. Passing in the string 'silent' will suppress the output.
Two output arguments are supported. EMF is a Nx3 or Nx6 matrix containing the effective mass fractions, where N is the number of modes in SHP. CMASS is the computed 3x3 or 6x6 mass matrix. The diagonals of this matrix correspond to the mass terms in each direction.