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Failing point of a lexan spheres?

  1. Jul 6, 2011 #1
    I'm a newby and have a project way out of my depth where a wrong calculation will be fatal...

    I need calculations of :

    1.how far a 2500mm and 3000mm sphere of lexan plastic 50mm thick can be submerged in sea water before it will implode/fail (in meters)? See data below.

    2.From what height can the either sphere be dropped from onto the sea water surface tension before failing?

    3.How much weight (kg) would it take to make the spheres neutrally buoyant (neither sink or float)?

    4.Can the stress formed in process (inside the sphere) be calculated and ratio to the above calcs? (e.g. For every mpa stress in structure will reduce the mpa of impak or pressure resistance/rating)

    Tensile Stress, yld, Type I, 50 mm/min 590 kgf/cm²
    Tensile Stress, brk, Type I, 50 mm/min 580 kgf/cm²
    Tensile Strain, yld, Type I, 50 mm/min 5.7 %
    Tensile Strain, brk, Type I, 50 mm/min 117.9 %
    Tensile Modulus, 50 mm/min 23000 kgf/cm²
    Flexural Stress, yld, 1.3 mm/min, 50 mm span 960 kgf/cm²
    Flexural Modulus, 1.3 mm/min, 50 mm span 22900 kgf/cm²
    Tensile Stress, yield, 50 mm/min 57 MPa
    Tensile Stress, break, 50 mm/min 56 MPa
    Tensile Strain, yield, 50 mm/min 5.4 %
    Tensile Strain, break, 50 mm/min 119.4 %
    Tensile Modulus, 1 mm/min 2340 MPa
    Flexural Stress, yield, 2 mm/min 89 MPa
    Flexural Modulus, 2 mm/min 2140 MPa
    Izod Impact, notched, 23°C 75 cm-kgf/cm
    Izod Impact, notched, -30°C 63 cm-kgf/cm
    Instrumented Impact Total Energy, 23°C 763 cm-kgf
    Izod Impact, notched 80*10*4 +23°C 47 kJ/m²
    Izod Impact, notched 80*10*4 -30°C 24 kJ/m²
    Charpy 23°C, V-notch Edgew 80*10*4 sp=62mm 61 kJ/m²
    Charpy -30°C, V-notch Edgew 80*10*4 sp=62mm 17 kJ/m²
  2. jcsd
  3. Jul 6, 2011 #2


    User Avatar

    Staff: Mentor

    You are not going to get help here with projects that could have life-safety implications. You need to engage a professional engineer to help with projects like that.

    Thread closed.
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