The picture above depicts the fate of a plastic rimmed kitchen strainer that was

Question

The picture above depicts the fate of a plastic rimmed kitchen strainer that was inappropriately used as a steaming basket (placed just above boiling water to suspend food in a metal pot).

Over time at these temperatures, the handle began to noticeable bend towards the ground. The picture was taken after a dozen or so uses. Note that the handle geometry (cross section) nor its mass has really changed with use.

How can this failure can be best characterized, in terms of mechanical response? (Asking for a friend.)

Options:

1. Elastic

2. Viscoelastic Creep

3. Viscoelastic Stress Relaxation

4. Fatigue

Explanation / Answer

Option 3 - viscoelastic stress relaxation.

This failures of the material is due to viscoelastic stress relaxation. Stress relaxation is a type of failure that occurs due to stress under constant strain. The material is a polymer that is the used to suspend the particles, during which the handle bends. The strain during the usage is constant and hence the failure is due to stress relaxation.

As the material is a polymer, the property of viscoelasticity is considered due to change in the temperature.

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