Depth Calc.py

# References: 
# WHOI TECHNICAL MEMORANDUM 3-81
# Roark's Formulas for Stress and Strain, 7th Edition

mpa_per_foot_sw = 0.003033693
mpa_hy_steel_youngs_modulus = 207000
hy_steel_poissons_ratio = 0.30
mpa_hy80_yield_strength = 550
mpa_hy100_yield_strength = 900
in_ssn21_beam = 41 * 12
in_ssn688_beam = 33 * 12

def calc_buckling_pressure(
    youngs_modulus,
    poissons_ratio,
    thickness,
    wall_diameter
):
    return (
        ((thickness / wall_diameter) ** 3) *
        ((2 * youngs_modulus) / (1 - poissons_ratio ** 2))
    )

def calc_buckling_pressure2(
    youngs_modulus,
    poissons_ratio,
    td
):
    return (
        ((td) ** 3) *
        ((2 * youngs_modulus) / (1 - poissons_ratio ** 2))
    )

def calc_td(
    pressure,
    youngs_modulus,
    poissons_ratio
):
    return (pressure * ((1 - poissons_ratio ** 2) / (2 * youngs_modulus))) ** (1/3)

def calc_collapse_pressure(
    yield_strength,
    thickness,
    wall_diameter
):
    return (
        yield_strength *
        (1 - ((1 - 2*(thickness/wall_diameter)) ** 2))
    )

def calc_depth(mpa_pressure):
    return mpa_pressure/mpa_per_foot_sw