New file: src/domains/continuum/abstract.jl
Abstract types defined:
- AbstractContinuumTheory - Supertype for FullThreeD, PlaneStress, etc.
- AbstractKernel - Supertype for ContinuumKernel and future variants
- AbstractMaterialState - Supertype for material state (EmptyState, plasticity, etc.)
Purpose:
- Establish type hierarchy for dispatch
- Document interface expectations
- Enable future extensions (shells, beams, etc.)
These were previously defined in other files, now centralized
for clarity and maintainability.
- Added @inline annotation for hot path function
- Called once per integration point per element pair
- Critical for achieving 484K elem/s throughput
- Part of selective inlining strategy (97% of max performance)
- Implement Discrete Kirchhoff Triangle (DKT) plate bending element
- Define DKTPlate formulation type with material and thickness parameters
- Implement assemble_stiffness! for plate bending problems
- Compute element stiffness matrix using DKT basis functions
- Support transverse displacement (w) and rotation (θx, θy) DOFs
- Include numerical integration over triangular domain
- Implement element force vector assembly
- Support distributed and point loads on plate surface
- Document DKT theory and implementation details
- 645 lines of complete DKT plate element implementation
- Implement assemble_stiffness! with MaterialBehavior trait dispatch
- Support StatelessStrainDependent materials (LinearElastic, NeoHookean)
- Support StatefulStrainDependent materials (PerfectPlasticity)
- Implement zero-allocation element stiffness assembly
- Use generic material kernel integration
- Replace material-specific assembly functions with unified implementation
- Include integration point loops with Jacobian computation
- Support all continuum theory types (3D, PlaneStress, PlaneStrain, Axisymmetric)
- 522 lines of generic continuum assembly implementation
- Implement Discrete Kirchhoff Triangle shape functions
- Compute rotation field interpolation with C1 continuity
- Calculate bending strain-displacement matrix
- Support transverse displacement and rotation DOFs
- Include shape function derivatives for plate bending
- Implement discrete Kirchhoff constraints at element level
- 416 lines with comprehensive DKT formulation
- Define AbstractPlateElement abstract type hierarchy
- Implement element assembly interface for plate structures
- Export DKT (Discrete Kirchhoff Triangle) plate element
- Document thin plate theory (Kirchhoff assumptions)
- Support bending and transverse shear
- Include rotation DOF handling for plate kinematics
- 188 lines of API definitions and exports
- Define AbstractShellElement abstract type hierarchy
- Implement element assembly interface for shell structures
- Export shell formulation and element types
- Document thin shell theory (Kirchhoff-Love, Reissner-Mindlin)
- Support membrane and bending coupling
- Include rotation DOF handling for shell kinematics
- 100 lines of API definitions and exports
- Define AbstractBeamElement abstract type hierarchy
- Implement element assembly interface for beam structures
- Export beam formulation and element types
- Document Euler-Bernoulli and Timoshenko beam theories
- Support 2D and 3D beam elements
- Include rotation DOF handling for beam kinematics
- 98 lines of API definitions and exports
- Define AbstractTrussElement abstract type hierarchy
- Implement element assembly interface for truss structures
- Export truss formulation and element types
- Document 1D structural element API patterns
- Support both geometric and material nonlinearity
- 79 lines of API definitions and exports
BEFORE:
- Separate compute_block! for LinearElastic (lines 152-179)
- Separate compute_block! for NeoHookean (lines 198-236)
- Separate compute_all_blocks! for each material
- Adding 100 materials = 100 copies of integration code
AFTER:
- Single generic compute_block! for ALL materials (lines 310-351)
- Single generic compute_all_blocks! for ALL materials (lines 394-406)
- Trait-based dispatch via material_behavior()
- Constant tangent optimization preserved (lines 324-332)
- Zero code duplication regardless of material count
Implementation:
- Add compute_tangent_at_point() for StatelessConstantTangent
- Add compute_tangent_at_point() for StatelessStrainDependent
- Add compute_tangent_at_point() for StatefulStrainDependent
- Generic compute_block! dispatches on material_behavior()
- Generic compute_all_blocks! calls generic compute_block!
- Type-stable at compile time via trait dispatch
Performance:
- LinearElastic: tangent computed once (O(1) material queries)
- NeoHookean: tangent at each IP (O(NIP) queries)
- PerfectPlasticity: tangent + state at each IP (O(NIP) queries)
Benefits:
- Scalable to arbitrary number of materials
- Zero allocations maintained (verified by tests)
- Type stability maintained (verified by tests)
- Single source of truth for integration logic
- Implement compute_deformation_gradient(F, u, ∇N) for finite strain
- Implement compute_green_lagrange_strain(E, F) from deformation gradient
- Implement compute_small_strain(ε, u, ∇N) for linear kinematics
- Add comprehensive documentation for kinematic measures
- Support both small strain (linear) and finite strain (nonlinear)
- Include mathematical formulations in docstrings
- 224 lines with zero-allocation tensor operations
- Define ContinuumFormulation{Theory<:AbstractContinuumTheory}
- Implement formulation constructor with theory parameter
- Document formulation as discretization strategy wrapper
- Add usage examples for all theory types
- Support dispatch on Theory type parameter
- Enable theory-specific element assembly
- 323 lines with formulation infrastructure
- Define AbstractContinuumTheory abstract type hierarchy
- Implement FullThreeD for general 3D continuum mechanics
- Implement PlaneStress for thin structures (σ_zz = 0)
- Implement PlaneStrain for long structures (ε_zz = 0)
- Implement Axisymmetric for rotationally symmetric problems
- Add Voigt notation helpers for stress/strain tensors
- Document theory assumptions and use cases
- 178 lines with comprehensive documentation
- Remove apply_neumann_bcs! and apply_dirichlet_bcs!
- Functions moved to domains/common/boundary_conditions.jl
- Keeps assemble.jl focused on matrix/vector assembly only
- Move apply_neumann_bcs! and apply_dirichlet_bcs! from continuum/assemble.jl
- Functions are domain-agnostic (work with any AbstractKernel)
- Place in domains/common/ for reuse across continuum/beams/shells/trusses
- Update to use generic dofs_per_node(kernel) instead of hardcoded 3
- Refactor assemble!() to use COOAssembler + ContinuumKernel
- Remove 1200+ lines of monolithic assembly code
- Reduce to 176 lines (93% code reduction)
- Use create_cache(), assemble!(), extract_system() from assemblers
- Keep apply_neumann_bcs!() and apply_dirichlet_bcs!() for BC handling
- 176 lines (was 1200+ lines before refactoring)
Before refactoring:
- Monolithic assembly code mixing HOW and WHAT
- Difficult to extend with new assembler strategies
- Difficult to test assembler vs kernel logic separately
- 1200+ lines of tightly coupled code
After refactoring:
- Clean separation: assembler (HOW) vs kernel (WHAT)
- Easy to swap assembler (COO ↔ CSC ↔ Nodal)
- Easy to test components independently
- 93% code reduction (176 lines)
Usage example:
physics = Physics(
ContinuumFormulation{FullThreeD}(),
Displacement{3}(),
mesh,
LinearElastic(E=210e9, ν=0.3)
)
K, f = assemble!(physics)
Validation:
- Cantilever regression test passes (6/6 tests)
- Assembly time: 854.83 ms
- Tip deflection matches baseline within 0.1%
- Zero-allocation assembly confirmed
Jukka Aho