Number
of Frequencies 
Lets you set the required number
of natural (resonant) frequencies to be calculated. The default is
to calculate the lowest five frequencies. Rigid body modes are
calculated by the FFEPlus solver. A body without any restraints has
six rigid body modes. Rigid body modes have zero frequencies
(infinite period). If the working scenarios of
the model include dynamic loads, it is important to calculate at
least one frequency that is higher than the frequency of the
load. In most situations, resonance is not desirable because it
causes failure. However, some devices exploit resonance to
trigger an event while providing measures to control the
excessive associated deformation.

Upper
Bound Frequency 
Lets you set the upper bound
frequency of the required frequency range. Use the default value of
zero unless you are not interested in natural frequencies higher
than a certain value. Entering zero results in calculating the
specified number of frequencies. For the
FFEPlus solver, you can specify the Number of Frequencies or the Upper Bound Frequency. For the
Direct Sparse and Intel Direct sparse solvers, you can only
specify the Number of
Frequencies and specify a frequency shift.

Calculate frequencies closest to (frequency
shift) 
Available for the Direct Sparse
and Intel Direct Sparse solvers. Select this option to specify a
frequency value of interest. The software calculates the frequencies
closest to the specified value. This option is referred to as
frequency shift in the literature. You can use this option to avoid
calculating rigid body modes. In cases where
the frequency analysis cannot run because of singularity of the
stiffness matrix, use the frequency shift option to overcome the
singularity issue. Increase the shift value gradually from zero
until the Direct Sparse solvers successfully calculates the
requested frequencies. If you set a higher
value for the frequency shift, the Direct Sparse solver
selectively calculates the requested number of frequencies,
which are clustered around the shift value. Thus, you can
avoid the computation of lower range frequencies (including
the rigid body modes), which may be of no interest to your
analysis, and save computational time.

Use inplane effect

This option is internally
activated to account for the effects of any applied loads on the
model's stiffness. See also SOLIDWORKS
Simulation Help: Use Inplane
Effect. 
Use
soft spring to stabilize model 
Select this option to add soft
springs to stabilize inadequately supported models. 