Anything that is not in the nonlinear part of the model is considered linear.
There are no specific guidelines for modeling the linear part of an HBM analysis. For general guidelines, see the Modeling and Meshing Guide.
Similar to a linear harmonic analysis, some form of damping should be specified in an HBM analysis. See Limitations for restrictions on damping definition.
Since HBM is a nonlinear analysis, it is more computationally intensive and requires more disk space than a linear harmonic analysis. To avoid prohibitive performance, the linear parts of the model may be reduced using component mode synthesis substructuring (CMS). For an example using CMS in an HBM analysis, see Example 3: Two Jointed Beams with Frictional Contact Interface.
Note that using CMS is a requirement for the following cases:
When prestress is included in the analysis, a linear perturbation generation procedure must be performed to obtain a superelement accounting for the prestress effect.
When cyclic symmetry is used and the harmonic index is greater than zero, a single stage superelement must be generated.
When considering body loads such as rotational velocities. These forces must be included in the substructure load vectors.