ModalReduction
Solve parametric or time-dependent problem using modal reduction.
Syntax
model.sol(sname).create(fname,"ModalReduction")
model.sol(sname).feature(fname).set(pname,pvalue)
Description
Operation feature. The following properties and values are accepted:
Table 6-51: Valid Modal Property/Value Pairs for the Modal Reduction
Property
Value
Default
Description
analysistype
frequency | transient
frequency
Solve for frequency response or transient response.
clist
String array
 
Provide values for constants as input parameters using a string array; for the corresponding constant names, use cname.
cname
String array
 
Provide names of constants as input parameters using a string array; for the corresponding constant values, use clist.
control
String
user
Name of the controlling study step or "user" if the feature is controlled manually.
dampratio
scalar | numeric vector
0
Damping ratios for participating modes.
eigsol
solution object
 
Pre-computed eigenpairs (or other vectors) to be used in the modal analysis.
keeplog
on | off
off
Keep warnings in stored log.
loadfact
string | vector of strings
empty
Scalar function(s) for time and/or parameter dependent boundary conditions.
maxstepbdf
positive scalar
1e-1
Maximum time step when maxstepconstraintbdf is const.
maxstepconstraintbdf
auto | const | expr
auto
Maximum time step for time-dependent modal analysis: automatic (auto), constant (const), or an expression (expr).
maxstepexpressionbdf
String
 
Expression for the maximum time step when maxstepconstraintbdf is expr.
message
String
 
The log message from the last solution process.
modes
integer vector
all
Participating modes.
outsollinearized
du | u
du
Store the total solution (u) or deviation and linerization point (du), when analysistype=frequency and storelinpoint=off.
plist
scalar | numeric vector
 
Frequency list. Only applicable when analysistype has been set to frequency.
pname
vector of strings
 
Parameter names.
pout
plist | fraction | spread
plist
Use plist as it stands or modify in relation to the participating modes.
romdata
String
new
Tag of the target container for the reduced model (new for a new reduced model).
romReconstruct
true | false
true
Enable reconstruction in the produced reduced model.
rtol
scalar
0.01
Relative tolerance. Only applicable when analysistype has been set to transient.
soltypemat
on | off
off
Store reduced model matrices.
soltypeonline
on | off
off
Create a reduced model.
soltypesol
on | off
on
Perform frequency sweep or transient simulation using the modal solver.
storelinpoint
on | off
off
Whether to store the linearization point.
tlist
scalar | numeric vector
 
Time list. Only applicable when analysistype has been set to transient.
In addition, the following properties are available for exporting matrices and vectors:
Table 6-52: Valid Modal Property/Value Pairs for Matrix and Vector Export from the Modal Solver
Property
Value
Default
Description
AllL
on | off
off
All load vectors, frequency.
B0r
on | off
off
Reduced initial value input matrix, transient.
B0rdot
on | off
off
Reduced initial time derivative input matrix, transient.
Br
on | off
off
Reduced input matrix, transient and frequency.
Brdot
on | off
off
Reduced time derivative input matrix, transient.
Brdotdot
on | off
off
Reduced second time derivative input matrix, transient.
Cr
on | off
off
Reduced output matrix, transient and frequency.
Cstate
on | off
off
State-space matrix C, transient.
Dc
on | off
off
State-space matrix D, transient.
DPartSol
on | off
off
Damping matrix times particular solution, frequency.
Dr
on | off
off
Reduced damping matrix, transient and frequency.
Dra
on | off
off
Damping ratio matrix, transient and frequency.
Dstate
on | off
off
State-space matrix D, transient.
EPartSol
on | off
off
Mass matrix times particular solution, frequency.
Er
on | off
off
Reduced mass matrix, transient and frequency.
F
on | off
off
Input feedback, transient and frequency.
Kr
on | off
off
Reduced stiffness matrix, transient and frequency.
Kud
on | off
off
Stiffness matrix times ud, transient.
L
on | off
off
Load vector, transient and frequency.
Pm
on | off
off
Projection matrix, transient and frequency.
U0
on | off
off
Initial value vector, transient.
Udot0
on | off
off
Initial derivative vector, transient.
Y0
on | off
off
Output bias, transient and frequency.
The reduced matrices are the matrices that result from the elimination of constraints in the discretized model.
For frequency response analysis, nonconstant Neumann boundary conditions and constant Dirichlet boundary conditions are supported. The only allowed type of parameter-dependent Dirichlet boundary condition are those that can be written as a constant vector times a scalar function. The scalar function is specified via the property loadfact. For transient response analysis only constant Dirichlet boundary conditions are supported. Neumann conditions that can be written as a constant vector times a scalar function (which is specified via the property loadfact) are supported for transient response.
The property modes is index 0 based.
If pout is set to fraction the output frequencies are the ones in plist multiplied by the absolute value of the largest eigenvalue in eigsol (or some other fraction of the largest participating eigenvalue of eigsol). The purpose of this property is to be able to automatically compute the frequency response for reasonable frequencies. If pout is set to spread then plist is interpreted as an interval around each participating eigenvalue. For example, if plist is set to range(0.9,0.04,1.1) then each participating eigenvalue is multiplied by this list, and the resulting lists are concatenated into the plist that is used.