ring stiffness of spiral plastic pipe

[AgeOfEmpire]

Hi friends,

I am working in plastic pipe test lab. I try to explain my problem.
In spiral sewage plastic pipes, ring stiffness is most important parameter. According to the DIN 16961, elasticity modulus of HDPE at 24h (380MPa) and moment of inertia are used to determine ring stiffness value of HDPE by theoretical. Ring stiffness is also determined by parallel plate loading test method by experimentally. Elasticity modulus of HDPE at 24h is also used to calculate load quantity.
the problem is differences of these method. ring stiffness which determined by theoretically is different from the experimantal ring stiffness.

Is there any friend who have some experience as my problem.

Thank you for your interest.

 

[BigInch]

Yes that can be a problem sometimes, which is why ovality and perhaps some other parameters are often needed to be introduced into the theoretical equations and why safety factors are still needed in the design equations.

Still more worrying, is that practical appplications often differ widely from experimental conditions, even when field conditions approximate labratory conditions, such as in the difference in the degree of support provided by a labratory hydrostatic type pressure distrabution verses the actual loading produced by soil, etc. and how much internal pressure stiffens the ring when combined with a point loads from a rock. Superposition only goes so far.

If you could predict every failure by theoretical means alone, safety factors would quickly become redundant. Don't look for them to go away soon.

"Make everything as simple as possible, but not simpler." - Albert Einstein (1879-1955)
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