*Heading
 Dickens 4 DOF Spring-mass Model
*Preprint, Model=yes
*Node, Nset=nall
 1, 0, 1
 2, 0, 2
 3, 0, 3
 4, 0, 4
*Element, Type=spring1, Elset=spring1
 1, 1
 5, 4
*Element, Type=spring2, Elset=spring2
 2, 1, 2
 3, 2, 3
 4, 3, 4
*Element, Type=mass, Elset=one
 6, 1
 7, 2
 8, 3
*Element, Type=mass, Elset=half
 9, 4
*Spring, Elset=spring1
 2
 10000.0
*Spring, Elset=spring2
 2, 2
 10000.0
*Mass, Elset=one
 1.
*Mass, Elset=half
 0.5
*Boundary
 nall, 1, 1
 nall, 3, 3
*Nset, Nset=out1
 3
*Nset, Nset=out2
 1
*Elset, Elset=elout
 4
**
** ===========================
**
*Step, Perturbation, Name=step-1
*Static
*Load Case, Name=lc1
*Cload
 3, 2, 1.0
*End load case
*End Step
*Step, Name=step-2
 Frequency Analysis
*Frequency, Normalization=mass, Residual Modes
 1,
*Output, field
*Node output, Nset=nall
 U
*End Step
**
** ===========================
**
*Step, Name=step-3
 SSD Direct
*Steady State Dynamics, Direct, interval=eigenfrequency
 3.,
*Cload
 3, 2, 1.0
*Output, Field
*Node Output, Nset=nall
 U
*Node Output, Nset=nall
 A
*Output, History
*Node Output, Nset=nall
 U2
*Node Output, Nset=nall
 A2
*End Step
**
** ===========================
**
*Step, Name=step-4
 SSD Mode-Based
*Steady State Dynamics, interval=eigenfrequency
 3.,
*Cload
 3, 2, 1.0
*Select Eigenmodes, Generate
 1, 2
*Modal Damping, Rayleigh
 1, 2, 0.02 
*Output, Field
*Node Output, Nset=nall
 U
*Node Output, Nset=nall
 A
*Output, History
*Node Output, Nset=nall
 U2
*Node Output, Nset=nall
 A2
*End Step