Topic: Force, temperature and deadweight loads: solution strategy?
I am working on a axisymmetric problem (with Axisymm3d elements), which is loaded by temperature, dead weight and edge load. I use the isotropic damage model.
The goal is to find safety factor for the edge load, i.e. first solve the temperature+dead weight problem (those two are given), then scale load level (for the edge load) until there is a solution.
Since the temperature increase is big (1280K), I define linear functions which increase the temperature and edge load to its reference values within the first 1s in 10 steps (deltaT 0.1), and then keep it constant.
My current approach is something like this:
# non-linear static with NR iteration
# vertical displacement of node 21 is what is good to know
NonLinearStatic nsteps 30 controllmode 1 MaxIter 100 stiffmode 1 deltaT 0.1 renumber 1 ddm 2 21 2 ddv 1 1 ddltf 2
## BCs ##
# fixed nodes
BoundaryCondition 1 loadTimeFunction 1 prescribedvalue 0.0
# dead weight, 33kN/m3 downwards (-y)
DeadWeight 2 loadTimeFunction 1 Components 2 0 -33e3
## load -46kN/m2: output from arch-geom/arch-static-loads.py
ConstantEdgeLoad 3 loadTimeFunction 2 Components 2 0.0 -46e3 loadType 3 ndofs 2 csType 0
# 1280: from ambient 20C to 1300C
StructTemperatureLoad 4 loadTimeFunction 2 Components 1 1280
## Time functions ##
# function for what is applied at the very beginning
ConstantFunction 1 f(t) 1.0
# function for what is applied progressively during the first "second"
PiecewiseLinFunction 2 nPoints 2 t 2 0.0 1.0 f(t) 2 0.0 1.0
## element properties for unv2oofem ##
group Group_Fixed
nodeprop bc 2 1 1
group Group_Edge
elemprop bLoadNum 3
etype[11]
group Group_Elements
elemprop crosssect 1 bodyLoads 2 2 4 mat 1
etype[41] Axisymm3DI would like to ask:
* Does the code do what I think it should? Incease load level, and also temperature (in the first second)?
* When I have troubles with convergence, what parameters can I tune? I don't even converge in the first thep at t=0, where the solution should be elastic - dead weight alone will not lead to any damage.
Thanks!