fix von mises stress and particle spacing (#886)

Co-authored-by: LasNikas <niklas.nehe@web.de>

Author: LasNikas

src/general/initial_condition.jl

@@ -239,6 +239,11 @@ function Base.union(initial_condition::InitialCondition, initial_conditions...)
     particle_spacing = initial_condition.particle_spacing
     ic = first(initial_conditions)
 
+    if initial_condition.particle_spacing isa Vector || ic.particle_spacing isa Vector
+        throw(ArgumentError("`union` operation does not support non-uniform particle spacings. " *
+                            "Please ensure all `InitialCondition`s use a scalar particle spacing."))
+    end
+
     if ndims(ic) != ndims(initial_condition)
         throw(ArgumentError("all passed initial conditions must have the same dimensionality"))
     end
@@ -272,6 +277,11 @@ Base.union(initial_condition::InitialCondition) = initial_condition
 function Base.setdiff(initial_condition::InitialCondition, initial_conditions...)
     ic = first(initial_conditions)
 
+    if initial_condition.particle_spacing isa Vector || ic.particle_spacing isa Vector
+        throw(ArgumentError("`setdiff` operation does not support non-uniform particle spacings. " *
+                            "Please ensure all `InitialCondition`s use a scalar particle spacing."))
+    end
+
     if ndims(ic) != ndims(initial_condition)
         throw(ArgumentError("all passed initial conditions must have the same dimensionality"))
     end
@@ -302,6 +312,11 @@ Base.setdiff(initial_condition::InitialCondition) = initial_condition
 function Base.intersect(initial_condition::InitialCondition, initial_conditions...)
     ic = first(initial_conditions)
 
+    if initial_condition.particle_spacing isa Vector || ic.particle_spacing isa Vector
+        throw(ArgumentError("`intersect` operation does not support non-uniform particle spacings. " *
+                            "Please ensure all `InitialCondition`s use a scalar particle spacing."))
+    end
+
     if ndims(ic) != ndims(initial_condition)
         throw(ArgumentError("all passed initial conditions must have the same dimensionality"))
     end

src/general/interpolation.jl

@@ -655,7 +655,7 @@ end
     end
 
     cache.jacobian[point] += det(deformation_gradient(system, neighbor)) * volume_b * W_ab
-    cache.von_mises_stress[point] += von_mises_stress(system) * volume_b * W_ab
+    cache.von_mises_stress[point] += von_mises_stress(system, neighbor) * volume_b * W_ab
 
     sigma = cauchy_stress(system)
     for j in axes(cache.cauchy_stress, 2), i in axes(cache.cauchy_stress, 1)

src/io/read_vtk.jl

@@ -57,7 +57,12 @@ function vtk2trixi(file)
             @info "No '$field' field found in VTK file. Will be set to zero."
         end
     end
-    return InitialCondition(; coordinates, particle_spacing=results["particle_spacing"],
+
+    particle_spacing = allequal(results["particle_spacing"]) ?
+                       first(results["particle_spacing"]) :
+                       results["particle_spacing"]
+
+    return InitialCondition(; coordinates, particle_spacing=particle_spacing,
                             velocity=results["velocity"],
                             mass=results["mass"],
                             density=results["density"],