def thickness_hoop(self, delta_P, D_o, t_corr, f_tol):
"""Number [Pa] -> Number [m]
Internal Pressure Containment
(Clause 6.4.2.2)
Considers:
- maximum internal pressure (design pressure)
- minimum external pressure (zero)"""
# Allowabe hoop stress
sig_h_a = self.pd8010.df_h*self.sig_y_d
t_thin = delta_P*D_o/(2*sig_h_a)
# Determine whether thick or thin wall
if t_thin/D_o >= 20:
t_h = t_thin
else:
def t_thick(t):
"""Equation (5)"""
eq = delta_P*((D_o**2+(D_o-2*t)**2)/(D_o**2-(D_o-2*t)**2))
return sig_h_a - eq
# Run Newton-Raphson solver
t_h = nr_solve(t_thick, x0=t_thin)
return self.pd8010.req_thickness(t_h, t_corr, f_tol)
def thickness_buckle(self, P_o, D_o):
"""Propagation Buckling Due to External Over Pressure
(Clause G.2)
Considers:
- minimum internal pressure (zero)
- maximum external pressure (at water depth, d)"""
def P_p(t):
"""Propagation pressure
Equation (G.21)"""
return 10.7*self.sig_y_d*(t/D_o)**2.25-P_o
return nr_solve(P_p)
def thickness_collapse(self, P_o, E, v, D_o, f_0):
"""Local Buckling Due to External Over Pressure
(Clause G.1.2)
Considers:
- minimum internal pressure (zero)
- maximum external pressure (at water depth, d)"""
def P_e(t):
"""Critical Pressure for an Elastic Critical Tube
Equation (G.2)"""
return 2*E/(1-v**2)*(t/D_o)**3
def P_y(t):
"""Yield Pressure
Equation (G.3)"""
return 2*self.sig_y_d*(t/D_o)
def char_resist(t):
"""Characteristic resistance for external pressure
Equation (G.1)"""
return ((P_o/P_e(t))-1) * ((P_o/P_y(t))**2-1) - (P_o/P_y(t))*f_0*(D_o/t)
return nr_solve(char_resist)
