(in progress) playing around with materials library

materials.py

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+"""Material library"""
+from gpkit import Model, Variable
+
+
+class Material(Model):
+    # todo: what should be common?
+    pass
+
+
+class Aluminum6061(Material):
+    def setup(self):
+        rho = Variable(r"\rho", 2.70, "g/cm^3", "density")
+        E = Variable("E", 69, "GPa", "Young's modulus")
+        sigma_y = Variable(r"\sigma_{y}", 55, "MPa", "yield stress")
+        # the objective and constraints are completely arbitrary.
+        # use case is accessing Variables (and their associated values)
+        return rho, [sigma_y <= E]
+
+
+if __name__ == "__main__":
+    pass

structures.py

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+from numpy import pi
+from gpkit import Model, Variable
+
+
+class ColumnBuckling(Model):
+    """Euler column buckling, from https://en.wikipedia.org/wiki/Buckling
+
+    For both ends pinned (hinged, free to rotate), K = 1.0.
+    For both ends fixed, K = 0.50.
+    For one end fixed and the other end pinned, K ~= 0.699.
+    For one end fixed and the other end free to move laterally, K = 2.0.
+    """
+    def setup(self):
+        F = Variable("F", "lbf", "vertical load on column")
+        E = Variable("E", "GPa", "modulus of elasticity")
+        I = Variable("I", 1e-9, "m^4", "area moment of inertia")
+        L = Variable("L", 1, "m", "unsupported length of column")
+        K = Variable("K", 2.0, '-', "column effective length factor")
+        return 1/F, [F <= pi**2*E*I / (K*L)**2]
+
+
+if __name__ == "__main__":
+    from materials import Aluminum6061
+    M = ColumnBuckling().merge(Aluminum6061())
+    M.solve()