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combine with path-following techniques

• load control
• displacement control
• arc-length

Maybe co-develop with

• #40

• model setup
• linear analysis
• stability analysis (eigenvalues, vectors)
• path-following
• post-buckling

• as part of the linear solver
• extend for nonlinear setup (should be minimal changes, if any)

• create an abstract ConvergenceTest class. One (or more) member(s) of that class shall be used by a Solver object to determine whether or not a current approximate solution shall be considered converged or not.

Subclasses

• max(abs(du) with option for absolute or relative tolerance
• max(abs(R)) with option for absolute or relative tolerance
• incremental energy, R.du with option for absolute or relative tolerance
• displacement control: G.du or G.u
• load control: converging to a load pattern for given displacement constraint
• arc-length constraints

Note pull frame element from CESG 506/CESG 507

linked with

• #5

• isotropic works with existing models when using Lagrange Form
• orthotropic needed

• modeling a continuous beam
• extracting moment and shear diagrams

• #5
• #6
• #7

May be subclassed from #28

Maybe co-develop with

• #41

Needed for plasticity

TODO

• add method to Element class
• add trigger to Solver

• eigenvalue analysis
• path-following
• post-buckling

Build upon

• #43
• #34

Requires

• #22
• #23
• #32

Requires

• #27
• #28

• define dof codes
• create index list for local dofs
• register elements
• create element specific maps (and memorize them)
• change fixity logic to use keys
• change loading logic to use keys

• P-delta
• variational form of beam
• needs to work with sectionModel

Subclass or co-develop with

• #38

That Solver shall include

• Assembler
• General Newton-Raphson solver
• Option to use modified Newton-Raphson
• Option to incorporate linear constraints (Constraint objects)
• Option to include a ConvergenceTest object (different criteria as helper classes)
• Send analysisConverged signal to allow for update of path-dependent material states.

might be combined with

• #35

Based on

• #37

Might be combined with

• #36

Requires

• #34
• #35
• #36
• #39
• #40
• #41

Convert from CESG 506 code(s)

Requires

• #24
• #25

Build upon

• #44
• #45

• create an abstract Constraint class to represent general linear and nonlinear constraints on a system

Subclass to:

• single point constraint
• multi-point constraint (could be further subclassed for various path-following constraints)
• constraint-elements (simple node-to-surface contact)
• energy-based constraints

Notes: Consider the following

• constraints can change between load steps, even between iteration steps (but need not)
• constraints may add to the tangent. May need to be part of the assembler.
• constraints may include material properties (springs, friction, break-off points, ...)

Isotropic, large strain

Build upon

• #43

• elastic response
• elastic-plastic response

Note: incomplete implementation