Yield Stress in 1 Minute

 

Video Transcript

Hi this is Joseph Hodges for the Rheology Lab.

In the context of semisolids, what we rheologists describe as structured liquids, yield stress is the stress at which material significantly begins to flow.

From pump specification, comparisons of spread ability or assessing the capability of the product to suspend large particles, yield stress is a highly important metric for predicting handling behaviour of structured materials.

You can think of yield stress as how hard would I need to push the material before it stops bouncing back.

There are multiple ways of measuring yield stress; The modulus crossover point, the stress at a phase angle of 45 degrees and the onset point are three common methods our lab uses depending on the situation.

In this real-world example, our high-powered realtors show that under very low stresses, orange juices and smoothies possess an incredibly delicate elastic structure and do undergo a yielding behaviour on application of sufficient stress.