create material data models

gpkitmodels/GP/aircraft/tail/horizontal_tail.py

@@ -3,7 +3,9 @@
 from gpkit import parse_variables
 from .tail_aero import TailAero
 from gpkitmodels.GP.aircraft.wing.wing import Wing
+from gpkitmodels.GP.aircraft.wing.wing_skin import WingSkin
 from gpkitmodels.GP.aircraft.wing.wing_core import WingCore
+from gpkitmodels.GP.materials.kevlar import Kevlar
 
 #pylint: disable=attribute-defined-outside-init, no-member
 #pylint: disable=exec-used, undefined-variable
@@ -41,11 +43,12 @@ class HorizontalTail(Wing):
     def setup(self, N=3):
         exec parse_variables(HorizontalTail.__doc__)
 
+        WingSkin.material = Kevlar()
         self.ascs = Wing.setup(self, N)
         self.planform.substitutions.update(
             {self.planform.AR: 4, self.planform.tau: 0.08,
              self.planform.lam: 0.8})
-        self.skin.substitutions.update({self.skin.rhocfrp: 0.049})
+        # self.skin.substitutions.update({self.skin.rhocfrp: 0.049})
         self.foam.substitutions.update({self.foam.Abar: 0.0548,
                                         self.foam.rhocore: 0.024})
 

gpkitmodels/GP/aircraft/tail/vertical_tail.py

@@ -3,6 +3,8 @@
 from .tail_aero import TailAero
 from gpkitmodels.GP.aircraft.wing.wing import Wing
 from gpkitmodels.GP.aircraft.wing.wing_core import WingCore
+from gpkitmodels.GP.aircraft.wing.wing_skin import WingSkin
+from gpkitmodels.GP.materials.kevlar import Kevlar
 
 #pylint: disable=attribute-defined-outside-init, no-member, exec-used
 
@@ -34,10 +36,10 @@ class VerticalTail(Wing):
     def setup(self, N=3):
         exec parse_variables(VerticalTail.__doc__)
 
+        WingSkin.material = Kevlar()
         self.ascs = Wing.setup(self, N)
         self.planform.substitutions.update(
             {self.planform.tau: 0.08, self.planform.lam: 0.8})
-        self.skin.substitutions.update({self.skin.rhocfrp: 0.049})
         self.foam.substitutions.update({self.foam.Abar: 0.0548,
                                         self.foam.rhocore: 0.024})
 

gpkitmodels/GP/aircraft/wing/wing_skin.py

@@ -1,18 +1,16 @@
 " wing skin "
 from gpkit import Model, Variable, parse_variables
+from gpkitmodels.GP.materials.cfrp import CFRP
 
 class WingSkin(Model):
     """ Wing Skin model
 
     Variables
     ---------
-    rhocfrp         1.6         [g/cm^3]        density of CFRP
     W                           [lbf]           wing skin weight
     g               9.81        [m/s^2]         gravitational acceleration
     t                           [in]            wing skin thickness
-    tmin            0.012       [in]            wing skin min gauge
     Jtbar           0.01114     [1/mm]          torsional moment of inertia
-    taucfrp         570         [MPa]           torsional stress limit
     Cmw             0.121       [-]             negative wing moment coeff
     rhosl           1.225       [kg/m^3]        sea level air density
     Vne             45          [m/s]           never exceed vehicle speed
@@ -29,24 +27,27 @@ class WingSkin(Model):
     -------------
     W       W_{\\mathrm{skin}}
     t       t_{\\mathrm{skin}}
-    tmin    t_{\\mathrm{min}}
     Jtbar   \\bar{J/t}
-    taucfrp \\tau_{\\mathrm{CFRP}}
     Cmw     C_{m_w}
     rhosl   \\rho_{\\mathrm{SL}}
     Vne     V_{\\mathrm{NE}}
 
     """
+    material = CFRP()
+
     def setup(self, surface):
         exec parse_variables(WingSkin.__doc__)
 
         croot = self.croot = surface.croot
         S = self.S = surface.S
         self.loading = WingSkinL
+        rho = self.material.rho
+        tau = self.material.tau
+        tmin = self.material.tmin
 
-        return [W >= rhocfrp*surface.S*2*t*g,
+        return [W >= rho*surface.S*2*t*g,
                 t >= tmin,
-                taucfrp >= 1/Jtbar/croot**2/t*Cmw*S*rhosl*Vne**2
+                tau >= 1/Jtbar/croot**2/t*Cmw*S*rhosl*Vne**2
                 ]
 
 class WingSkinL(Model):

gpkitmodels/GP/materials/cfrp.py

@@ -0,0 +1,21 @@
+from gpkit import Model, parse_variables
+
+class CFRP(Model):
+    """ Carbon Fiber Reinforced Plastic Material Properties
+
+    Variables
+    ---------
+    rho         1.6         [g/m^3]         density of CFRP
+    tmin        0.012       [in]            minimum gauge thickness
+    tau         570         [MPa]           torsional stress limit
+
+    LaTex Strings
+    -------------
+    rho         \\rho_{\\mathrm{CFRP}}
+    tmin        t_{\\mathrm{min-CFRP}}
+    tau         \\tau_{\\mathrm{CFRP}}
+
+    """
+    def setup(self):
+        exec parse_variables(CFRP.__doc__)
+

gpkitmodels/GP/materials/kevlar.py

@@ -0,0 +1,21 @@
+from gpkit import Model, parse_variables
+
+class Kevlar(Model):
+    """ Kevlar Material Properties
+
+    Variables
+    ---------
+    rho         0.049       [g/m^3]         density of Kevlar
+    tmin        0.012       [in]            minimum gauge thickness
+    tau         200         [MPa]           torsional stress limit
+
+    LaTex Strings
+    -------------
+    rho         \\rho_{\\mathrm{Kevlar}}
+    tmin        t_{\\mathrm{min-Kevlar}}
+    tau         \\tau_{\\mathrm{Kevlar}}
+
+    """
+    def setup(self):
+        exec parse_variables(Kevlar.__doc__)
+