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https://github.com/JuliaFEM/JuliaFEM.jl.git
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Jukka Aho
e7f0309f73
Demonstrates modern Physics API for solving elasticity problems using CPU backend with element assembly. Features: - Simple 2-element beam mesh (Hex8 elements, 12 nodes, 36 DOFs) - Immutable Element API with field-based material properties - Physics problem setup (Elasticity, continuum formulation) - Material properties: Steel (E=210 GPa, ν=0.3) Demonstrates workflow: 1. Create mesh (nodes dictionary + connectivity tuples) 2. Create Physics problem (Elasticity with continuum formulation) 3. Build elements with immutable API (fields tuple) 4. Add elements to physics Educational example showing modern API usage for elasticity problems with clean separation between geometry and physics (131 lines).
132 lines
4.0 KiB
Julia
132 lines
4.0 KiB
Julia
# Assembly Strategy Comparison - Simple Example
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#
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# Demonstrates the modern Physics API for solving elasticity problems.
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# Uses the CPU backend with element assembly.
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using JuliaFEM
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using LinearAlgebra
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using Printf
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println("="^70)
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println("Assembly Comparison - Modern Physics API")
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println("="^70)
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# ============================================================================
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# 1. Create Simple Mesh
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# ============================================================================
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println("\n[1] Creating mesh...")
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# Simple 2-element beam (Hex8 elements)
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nodes = Dict(
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1 => [0.0, 0.0, 0.0],
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2 => [1.0, 0.0, 0.0],
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3 => [2.0, 0.0, 0.0],
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4 => [0.0, 1.0, 0.0],
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5 => [1.0, 1.0, 0.0],
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6 => [2.0, 1.0, 0.0],
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7 => [0.0, 0.0, 1.0],
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8 => [1.0, 0.0, 1.0],
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9 => [2.0, 0.0, 1.0],
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10 => [0.0, 1.0, 1.0],
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11 => [1.0, 1.0, 1.0],
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12 => [2.0, 1.0, 1.0]
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)
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connectivity_hex = [
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(1, 2, 5, 4, 7, 8, 11, 10),
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(2, 3, 6, 5, 8, 9, 12, 11)
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]
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n_nodes = length(nodes)
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n_elements = length(connectivity_hex)
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n_dofs = 3 * n_nodes
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println(" Nodes: $n_nodes")
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println(" Elements: $n_elements")
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println(" DOFs: $n_dofs")
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# ============================================================================
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# 2. Create Physics Problem
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# ============================================================================
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println("\n[2] Creating physics problem...")
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physics = Physics(Elasticity, "simple beam", 3)
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physics.properties.formulation = :continuum
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physics.properties.finite_strain = false
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# Create elements with new immutable API
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elements = Element[]
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for conn in connectivity_hex
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# Extract node coordinates
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X = [nodes[i] for i in conn]
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# Create immutable element with all fields
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element = Element(Hex8, conn,
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fields=(geometry=X,
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youngs_modulus=210e9, # Steel
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poissons_ratio=0.3))
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push!(elements, element)
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end
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add_elements!(physics, elements)
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println(" Elements added: $(length(physics.body_elements))")
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# ============================================================================
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# 3. Apply Boundary Conditions
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# ============================================================================
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println("\n[3] Applying boundary conditions...")
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# Fix left end (nodes 1, 4, 7, 10)
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fixed_nodes = [1, 4, 7, 10]
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add_dirichlet!(physics, fixed_nodes, [1, 2, 3], 0.0)
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println(" Fixed nodes: $(length(fixed_nodes)) (all DOFs)")
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println(" Total Dirichlet BCs: $(length(physics.bc_dirichlet.node_ids))")
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# Note: External forces would be applied via Neumann BC or body forces
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# For this simple demo, we solve with zero external loading
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# ============================================================================
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# 4. Solve with CPU Backend
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# ============================================================================
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println("\n[4] Solving with CPU backend...")
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t_solve = @elapsed begin
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sol = solve!(physics; backend=CPU(), tol=1e-6, max_iter=1000)
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end
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println(" Solve time: $(round(t_solve * 1000, digits=2)) ms")
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println(" CG iterations: $(sol.cg_iterations)")
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println(" Newton iterations: $(sol.newton_iterations)")
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println(" Residual: $(sol.residual)")
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println(" Max displacement: $(maximum(abs.(sol.u)) * 1000) mm")
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# ============================================================================
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# 5. Summary
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# ============================================================================
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println("\n" * "="^70)
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println("SUMMARY")
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println("="^70)
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println("\nProblem:")
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println(" Nodes: $n_nodes")
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println(" Elements: $n_elements")
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println(" DOFs: $n_dofs")
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println(" Fixed DOFs: $(3 * length(fixed_nodes))")
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println("\nSolution:")
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println(" Backend: CPU (element assembly + CG)")
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println(" Solve time: $(round(t_solve * 1000, digits=2)) ms")
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println(" CG iterations: $(sol.cg_iterations)")
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println(" Newton iterations: $(sol.newton_iterations)")
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println(" Residual: $(sol.residual)")
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println(" Max displacement: $(maximum(abs.(sol.u)) * 1000) mm")
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println("\n" * "="^70)
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println("✓ Modern Physics API working on CPU!")
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println("="^70)
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