# Failing point of a lexan spheres?

1. Jul 6, 2011

### aussie101

Hi
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)

MECHANICAL
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
IMPACT
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. Jul 6, 2011

### 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.