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Merge pull request #7 from Argonne-National-Laboratory/network_fix
Fix issues with the spring based "system" model
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,174 @@ | ||
| import numpy as np | ||
| import numpy.linalg as la | ||
| import networkx as nx | ||
|
|
||
| class Network(nx.MultiGraph): | ||
| """ | ||
| Simplified version of panel network where everything is an elastic spring | ||
| Boundary conditions are always fixed on the bottom and free on the top | ||
| """ | ||
| def __init__(self, *args, **kwargs): | ||
| super().__init__(*args, **kwargs) | ||
| if len(args) == 0: | ||
| self.add_node("top", distance = 0) | ||
| self.cpanel = 0 | ||
|
|
||
| def add_panel(self, k): | ||
| """ | ||
| Add a panel to the network with stiffness k | ||
| Parameters: | ||
| k: either a float stiffness or "rigid" or "disconnect" | ||
| Returns: | ||
| id of the new panel | ||
| """ | ||
| name = self._panel_name(self.cpanel) | ||
| self.cpanel += 1 | ||
| self.add_node(name, distance = 1) | ||
| self.add_edge("top", name, stiffness = k) | ||
|
|
||
| return self.cpanel - 1 | ||
|
|
||
| def add_tube(self, panel, kconnect, k): | ||
| """ | ||
| Add a tube to a panel | ||
| Parameters: | ||
| panel: panel id | ||
| kconnect: either a float stiffness or "rigid" or "disconnect" | ||
| k: float stiffness | ||
| """ | ||
| if panel >= self.cpanel: | ||
| raise ValueError("Panel %i does not exist!" % panel) | ||
|
|
||
| name = self._tube_name(panel, self._next_tube(panel)) | ||
| self.add_node(name+"_top", distance = 2) | ||
| self.add_node(name+"_bottom", distance = 3) | ||
|
|
||
| self.add_edge(self._panel_name(panel), name+"_top", stiffness = kconnect) | ||
| self.add_edge(name+"_top",name+"_bottom", stiffness = k) | ||
|
|
||
| def simplify_network(self): | ||
| """ | ||
| Simplify the tube network and return a list of subproblems | ||
| """ | ||
| # Remove all rigid nodes | ||
| self._remove_rigid() | ||
|
|
||
| # Split at all disconnects | ||
| return self._split_disconnect() | ||
|
|
||
| def solve_network(self, tforce): | ||
| """ | ||
| Impose the standard BCs and solve for the displacements at each node | ||
| Parameters: | ||
| tforce: thermal force on the bars | ||
| """ | ||
| n = len(self) | ||
| K = np.zeros((n,n)) | ||
| d = np.zeros((n,)) | ||
| f = np.zeros((n,)) | ||
|
|
||
| # Make the dof maps | ||
| self.backmap = {} | ||
| for i,name in enumerate(self.nodes()): | ||
| self.backmap[name] = i | ||
|
|
||
| # Fix all the ones with "_bottom" in the name to zero | ||
| fixed = [] | ||
| for i,name in enumerate(self.nodes()): | ||
| if name[:4] == "tube" and name.split('_')[1] == "bottom": | ||
| fixed.append(i) | ||
| free = sorted(list(set(list(range(n))) - set(fixed))) | ||
|
|
||
| # Impose the thermal force and the stiffness matrix | ||
| for a,b,data in self.edges(data=True): | ||
| dofs = [self.backmap[a],self.backmap[b]] | ||
| s = np.sign(self.nodes[b]['distance']-self.nodes[a]['distance']) | ||
| K[np.ix_(dofs,dofs)] += ( | ||
| data['stiffness']*np.array([[1,-1],[-1,1]])) | ||
|
|
||
| if a[:4] == 'tube' and b[:4] == 'tube': | ||
| f[dofs] += tforce * np.array([1,-1]) * s | ||
|
|
||
| # Solve | ||
| fprime = f[free] - np.dot(K[np.ix_(free,fixed)], d[fixed]) | ||
| Kprime = K[np.ix_(free,free)] | ||
| dprime = la.solve(Kprime,fprime) | ||
| d[free] = dprime | ||
|
|
||
| # Backsub the displacements | ||
| for i, (name,data) in enumerate(self.nodes(data=True)): | ||
| data['displacement'] = d[i] | ||
|
|
||
| def _remove_rigid(self): | ||
| """ | ||
| Remove all rigid connections by deleting the edge and joining the | ||
| nodes | ||
| """ | ||
| while True: | ||
| for a,b,key,data in self.edges(data=True,keys=True): | ||
| if data['stiffness'] == "rigid": | ||
| self.remove_edge(a,b,key=key) | ||
| # Need to keep the one marked "tube" | ||
| if a[:4] == "tube": | ||
| ng = nx.contracted_nodes(self, a, b) | ||
| else: | ||
| ng = nx.contracted_nodes(self, b, a) | ||
| self.clear() | ||
| self.update(ng) | ||
| break | ||
| else: | ||
| break | ||
|
|
||
| def _split_disconnect(self): | ||
| """ | ||
| Split the graph at all disconnects | ||
| """ | ||
| # First just split | ||
| while True: | ||
| for i,j,key,data in self.edges(keys = True, data = True): | ||
| if data['stiffness'] == 'disconnect': | ||
| self.remove_edge(i,j,key = key) | ||
| break | ||
| else: | ||
| break | ||
|
|
||
| # Setup the new structures | ||
| base = [Network(self.subgraph(c)) for c in nx.connected_components(self) if len(c) > 1] | ||
| nstructs = [] | ||
| for b in base: | ||
| ns = [n[:4] for n in b.nodes()] | ||
| if "tube" in ns: | ||
| nstructs.append(b) | ||
|
|
||
| return nstructs | ||
|
|
||
| def _panel_name(self, k): | ||
| """ | ||
| Turn an integer into a panel id | ||
| Parameters: | ||
| k: panel integer id | ||
| """ | ||
| return "panel-%i" % k | ||
|
|
||
| def _tube_name(self, panel, tube): | ||
| """ | ||
| Turn integer panel and tube ids into a base tube string id | ||
| """ | ||
| return "tube-%i-%i" % (panel, tube) | ||
|
|
||
| def _next_tube(self, panel): | ||
| """ | ||
| Figure out what the next tube id is for a panel | ||
| """ | ||
| start = 0 | ||
| for n in self.neighbors(self._panel_name(panel)): | ||
| if n != "top": | ||
| start += 1 | ||
|
|
||
| return start |
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