dx4, D = elasprepFD(dx,Te,E=1E11,nu=0.25)
    
    Defines the variables (except for the subset flexural rigidity) that are
    needed to run "coeff_matrix_1d"

def elasprepFD(self):
    """
    dx4, D = elasprepFD(dx,Te,E=1E11,nu=0.25)
    
    Defines the variables (except for the subset flexural rigidity) that are
    needed to run "coeff_matrix_1d"
    """
    self.dx4 = self.dx**4
    self.D = self.E*self.Te**3/(12*(1-self.nu**2))