Question 12.2: A constant time section of 1000 h taken through a series of ...
A constant time section of lo00 h taken through a series of strain-time creep curves obtained for a particular polymer at various stress levels yields the following isochronous stress-strain data.
σ(kN/m^{2}) 1.0 2.25 3.75 5.25 6.54 7.85 9.0
ε(%) 0.23 0.52 0.85 1.24 1.68 2.17 2.7
The polymer is now used to manufacture:
(a) a disc of thickness 6 mm, which is to rotate at 500 rev/min continuously,
(b) a diaphragm of the same thickness which is to be subjected to a uniform lateral pressure of 16 N/m^{2} when clamped around its edge.
Determine the radius required for each component in order that a limiting stress of 6 k N/m^{2} is not exceeded after l000 hours of service. Hence find the maximum deflection of the diaphragm after this lo00 hours of service.
The lateral strain ratio for the polymer may be taken as 0.45 and its density as 1075 kN/m^{3}.
Our explanations are based on the best information we have, but they may not always be right or fit every situation.
Learn more on how we answer questions.