User Area > Advice
Typical
error message from LUSAS Solver text output file (*.OUT):
***ERROR*** ATTEMPTING
TO REFORM STIFFNESS MATRIX IN A LINEAR STATIC ANALYSIS
PLEASE CHECK DATA COMMANDS SPECIFIED AFTER ELEMENT/NODE OUTPUT
CONTROL (MNLNPF PROCESSOR)
The
most common cause of this error is the assignment of supports in
loadcases other than the first loadcase only in a linear static
analysis. In a linear static analysis you cannot change
supports from one loadcase to the next. All supports must be
assigned in the first loadcase only and these will be used for all
loadcases. The solution is to ensure that supports are only
assigned in the first loadcase.
If
supports are intended to change from one loadcase to the next in a nonlinear
or transient analysis, then
this error suggests that a Nonlinear & Transient Control
needs to be added to all the loadcases in the model. To do
this, right click on the loadcase in the Loadcase Tree View and
select Nonlinear & Transient Control.
Other
causes of this error in a linear static analysis may be the
assignment of other attributes that require a nonlinear analysis,
however other more specific errors will generally be encountered
instead. Some of such errors are given below.
***ERROR***
NONLINEAR CONTROL MUST BE USED IF AN ACTIVATE OR DEACTIVATE ELEMENTS
DATA
CHAPTER HAS BEEN SPECIFIED (OVERL6 PROCESSOR)
When
birth and death (also known as activation/deactivation) is
assigned in a linear analysis.
***ERROR***
ELEMENT P HAS NONLINEAR MATERIAL MODEL IN A LINEAR PROBLEM (XTNDSS
PROCESSOR)
When
nonlinear material is assigned in a linear analysis.
***ERROR***
SLIDELINE P IS OF A TYPE THAT IS ONLY PERMITTED IN NONLINEAR
PROBLEMS (SLCKAS PROCESSOR)
When
slideline (except tied slideline which is linear) is assigned in a linear
analysis.
To
resolve any of these errors there are two choices:
-
In
a linear static analysis should have any nonlinearity removed
from the assigned attributes.
-
In
a nonlinear analysis, a Nonlinear
& Transient Control needs to be added to all the
loadcases in the model.
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