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https://github.com/JuliaFEM/JuliaFEM.jl.git
synced 2026-08-16 10:34:12 +00:00
frictional contact tests, not working yet
This commit is contained in:
Jukka Aho
@@ -27,6 +27,7 @@ function append!(assembly::Assembly, sub_assembly::Assembly)
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append!(assembly.C2, sub_assembly.C2)
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append!(assembly.D, sub_assembly.D)
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append!(assembly.g, sub_assembly.g)
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append!(assembly.c, sub_assembly.c)
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end
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function assemble!(problem::Problem, time::Float64; empty_assembly::Bool=true)
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+126
-59
@@ -668,10 +668,15 @@ type Mortar <: BoundaryProblem
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tangential_condition :: Symbol # Stick or Slip
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minimum_distance :: Float64 # don't check for a contact if elements are far enough
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store_debug_info :: Bool # for making debugging easier
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always_in_contact :: Vector{Int64} # nodes in this list always in contact
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always_in_stick :: Vector{Int64} # nodes in this list always in stick
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always_in_slip :: Vector{Int64} # nodes in this list always in slip
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contact :: Bool
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friction :: Bool
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end
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function Mortar()
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Mortar(:Dual, false, :Tie, :Stick, Inf, false)
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Mortar(:Dual, false, :Tie, :Stick, Inf, false, [], [], [], false, false)
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end
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function get_unknown_field_name(::Type{Mortar})
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@@ -699,6 +704,15 @@ function assemble!{E<:MortarElements2D}(assembly::Assembly, problem::Problem{Mor
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slave_dofs = get_gdofs(slave_element, field_dim)
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local_assembly = Assembly()
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nnodes = size(slave_element, 2)
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c = zeros(2*nnodes)
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u = zeros(2*nnodes)
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u1 = zeros(2*nnodes)
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u2 = zeros(2*nnodes)
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la = zeros(2*nnodes)
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for master_element in slave_element["master elements"]
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# if distance between elements is "far enough" cannot expect contact
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@@ -715,10 +729,9 @@ function assemble!{E<:MortarElements2D}(assembly::Assembly, problem::Problem{Mor
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xi1b = project_from_master_to_slave(slave_element, master_element, [ 1.0])
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xi1 = clamp([xi1a xi1b], -1.0, 1.0)
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l = 1/2*abs(xi1[2]-xi1[1])
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l > 1.0e-9 || continue # no contribution
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isapprox(l, 0.0) && continue # no contribution
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# Calculate slave side projection matrix D
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nnodes = size(slave_element, 2)
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Ae = zeros(nnodes, nnodes)
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De = zeros(nnodes, nnodes)
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Me = zeros(nnodes, nnodes)
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@@ -767,7 +780,7 @@ function assemble!{E<:MortarElements2D}(assembly::Assembly, problem::Problem{Mor
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end
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end
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# Calculate normal-tangential constraints and initial weighted gap
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# Calculate normal-tangential constraints
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X1 = vec(slave_element("geometry", time))
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X2 = vec(master_element("geometry", time))
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Q = slave_element("normal-tangential coordinates", time)
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@@ -780,79 +793,133 @@ function assemble!{E<:MortarElements2D}(assembly::Assembly, problem::Problem{Mor
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D2 = zeros(2*nnodes, 2*nnodes)
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C2S2 = Q2'*C1S2
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C2M2 = Q2'*C1M2
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# initial weighted gap
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G = -(C2S2*X1 - C2M2*X2)
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# Calculate weighted gap in deformed configuration
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if haskey(slave_element, "displacement")
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u1 = vec(slave_element("displacement", time))
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else
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u1 = zeros(2*nnodes)
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end
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if haskey(master_element, "displacement")
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u2 = vec(master_element("displacement", time))
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else
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u2 = zeros(2*nnodes)
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end
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x1 = X1 + u1
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x2 = X2 + u2
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g = -(C2S2*x1 - C2M2*x2)
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# weighted gap change caused by deformation
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u = -(C2S2*u1 - C2M2*u2)
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# weighted gap in current configuration
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#g = -(C2S2*x1 - C2M2*x2)
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g = G + u
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# Calculate "complementarity condition"
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if haskey(slave_element, "reaction force")
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if haskey(slave_element, "reaction force")
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la = vec(slave_element("reaction force", time))
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else
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la = zeros(2*nnodes)
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end
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c = Q2'*la - g
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active_nodes = find(c[1:field_dim:end] .> 0)
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inactive_nodes = find(c[1:field_dim:end] .<= 0)
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# normal constraint: if contact, remove inactive nodes
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if problem.properties.normal_condition == :Contact
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if length(active_nodes) == 0
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# all nodes inactive, nothing to contribute
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return
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end
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for j in inactive_nodes
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dofs = [2*(j-1)+1, 2*(j-1)+2]
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G[dofs] = 0
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C1S2[dofs,:] = 0
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C1M2[dofs,:] = 0
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C2S2[dofs,:] = 0
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C2M2[dofs,:] = 0
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end
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end
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# tangential constraint: stick or slip
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if problem.properties.tangential_condition == :Slip
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D2 = copy(C2S2)
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D2[1:field_dim:end, :] = 0
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C2S2[2:field_dim:end, :] = 0
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C2M2[2:field_dim:end, :] = 0
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end
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# Add contributions
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add!(assembly.C1, slave_dofs, slave_dofs, C1S2)
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add!(assembly.C1, slave_dofs, master_dofs, -C1M2)
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add!(assembly.C2, slave_dofs, slave_dofs, C2S2)
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add!(assembly.C2, slave_dofs, master_dofs, -C2M2)
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add!(assembly.D, slave_dofs, slave_dofs, D2)
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add!(assembly.c, slave_dofs, c)
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add!(assembly.g, slave_dofs, G)
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add!(local_assembly.C1, slave_dofs, slave_dofs, C1S2)
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add!(local_assembly.C1, slave_dofs, master_dofs, -C1M2)
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add!(local_assembly.C2, slave_dofs, slave_dofs, C2S2)
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add!(local_assembly.C2, slave_dofs, master_dofs, -C2M2)
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add!(local_assembly.D, slave_dofs, slave_dofs, D2)
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add!(local_assembly.c, slave_dofs, c)
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add!(local_assembly.g, slave_dofs, G)
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if props.store_debug_info
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slave_element["G"] = G
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slave_element["g"] = g
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slave_element["c"] = c
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slave_element["C1S2"] = C1S2
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slave_element["C1M2"] = C1M2
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slave_element["C2S2"] = C2S2
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slave_element["C2M2"] = C2M2
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slave_element["D2"] = D2
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slave_element["active nodes"] = active_nodes
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end
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end # all master elements are done
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# if only equality constraints, i.e., mesh tying problem, we're done for this element.
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if !props.contact
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append!(assembly, local_assembly)
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return
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end
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C1 = sparse(local_assembly.C1)
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C2 = sparse(local_assembly.C2)
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D = sparse(local_assembly.D)
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g = sparse(local_assembly.g)
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c = sparse(local_assembly.c)
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# normal condition
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cn = c[1:field_dim:end]
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inactive_nodes = find(cn .<= 0)
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active_nodes = find(cn .> 0)
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# inactive element
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if length(active_nodes) == 0
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return
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end
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# normal constraint: remove inactive nodes
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for j in inactive_nodes
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if length(props.always_in_contact) != 0
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j in props.always_in_contact && continue
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end
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dofs = [2*(j-1)+1, 2*(j-1)+2]
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C1[dofs,:] = 0
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C2[dofs,:] = 0
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g[dofs] = 0
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end
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# frictionless contact
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if !props.friction
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for j in active_nodes
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dofs = [2*(j-1)+1, 2*(j-1)+2]
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D[dofs[2],dofs] = C2[dofs[2],dofs]
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C2[dofs[2],:] = 0
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g[dofs[2]] = 0
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end
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local_assembly.C1 = C1
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local_assembly.C2 = C2
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local_assembly.D = D
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local_assembly.g = g
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local_assembly.c = c
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append!(assembly, local_assembly)
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return
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end
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# frictional contact, see Gitterle2010
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mu = 0.3
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lat = la[2:field_dim:end]
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ut = u[2:field_dim:end]
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ct = lat + ut
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println("cn, ct, lat")
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println(cn)
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println(ct)
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println(lat)
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println("full(cn)")
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prinln(full(cn))
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C = max(mu*cn, abs(ct))*lat - mu*max(0, cn)*ct
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stick_nodes = find(abs(ct) - mu*cn .< 0)
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slip_nodes = find(abs(ct) - mu*cn .>= 0)
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stick_nodes = setdiff(stick_nodes, inactive_nodes)
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slip_nodes = setdiff(slip_nodes, inactive_nodes)
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for j in active_nodes
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dofs = [2*(j-1)+1, 2*(j-1)+2]
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D[dofs[2],dofs] = C2[dofs[2],dofs]
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C2[dofs[2],:] = 0
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g[dofs[2]] = C[dofs[2]]
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end
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if props.store_debug_info
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slave_element["G"] = G
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slave_element["g"] = g
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slave_element["c"] = c
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slave_element["C1"] = C1
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slave_element["C2"] = C2
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slave_element["D"] = D2
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slave_element["active nodes"] = active_nodes
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end
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local_assembly.C1 = C1
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local_assembly.C2 = C2
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local_assembly.D = D
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local_assembly.g = g
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local_assembly.c = c
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append!(assembly, local_assembly)
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end
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typealias MortarElements3D Union{Tri3, Quad4}
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@@ -48,6 +48,47 @@ end
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function handle_overconstraint_error!(problem, nodes, all_dofs, C1_, C1, C2_, C2, D_, D, g_, g)
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# old, new, old, new...
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#= herzian contact with symmetry boundary
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# INFO: SUMMARY for node id 555 with dofs 1109, 1110:
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# INFO: ----- Current constraint -----
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# INFO: lambda coefficients in C1 matrix are:
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# INFO: dof 1109: ⋯ + 0.15*λ₁₁₀₉ ⋯
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# INFO: rows in constraint matrix C2 & D
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# INFO: dof 1109: 0.15*u₁₁₀₉ = -0.0 <-- overconstrained dof
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# INFO: ----- New constraint -----
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# INFO: lambda coefficients in C1 matrix are:
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# INFO: dof 1109: ⋯ + 0.15*λ₁₁₀₉ ⋯
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# INFO: dof 1110: ⋯ + 0.15*λ₁₁₁₀ ⋯
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# INFO: rows in constraint matrix C2 & D
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# INFO: dof 1109: 0.0*u₁₅₃ - 0.0*u₁₅₄ - 0.0*u₁₅₅ + 0.15*u₁₅₆ + 0.0*u₁₁₀₉ - 0.15*u₁₁₁₀ = -0.0 <-- overconstrained dof
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# INFO: dof 1110: 0.15*λ₁₁₀₉ + 0.0*λ₁₁₁₀ = -0.0
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# INFO: ----- Related equations -----
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# INFO: dof 1110: 0.15*λ₁₁₀₉ + 0.0*λ₁₁₁₀ = -0.0
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# INFO: dof 155: 0.165*u₁₅₅ = 0.0
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# INFO: algorithm 1 solved issue? false
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# INFO: algorithm 2 solved issue? true
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# INFO: fixed: new setting is
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# INFO: dof 1109: 0.0*u₁₅₃ - 0.0*u₁₅₄ - 0.0*u₁₅₅ + 0.15*u₁₅₆ + 0.0*u₁₁₀₉ - 0.15*u₁₁₁₀ = -0.0
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if 555 in nodes
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info("overconstraint DIRTY HACK")
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# It is possible to selectively remove mortar constraints and the associated
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# Lagrange multiplier components in certain axis directions and replace them
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# with the Dirichlet (symmetry) conditions.
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# old configuration is dirichlet symmetry condition
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# new configuration is mortar constraint
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# 1. remove mortar constrains and associated Lagrange multiplier components
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# in dof 1109, that is, x direction of node 555.
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C1[1109,:] = 0
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C2[1109,:] = 0
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D[1109,:] = 0
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g[1109,:] = 0
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# D[1110,1110] = 0
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# g[1110] = 0
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return
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end
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=#
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""" Return all other dofs which connects to overconstrained dofs. """
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function get_related_dofs(dofs)
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dofs_ = Set(dofs)
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