Some people I've notice like to use the words stress and strain interchangeably, which they are not. Stress represents how much force an object can withstand while strain represents the object deflection. However both stress and strain can be related to one another through Hook's Law.

Stress

In most cases stress is what is calculated, and there are many different ways to calculate stress depending on the type of loading that is placed on the part. The reason why, stress is so important to know is because it tells the engineer whether an object is going to yield or if it can bear the load placed on. Equation 1 and 2 show how to calculate the stress on the object if it is under a basic shear force or a basic normal force.

(1)

(2)

Strain

As mentioned earlier strain is the area of strength of materials that is used to determine how much an object will deflect. There are a few reasons why it would be important to know the strain on a part. First, there is a possibility that parts could have interference due to deflection. Plus, if there is sensor that needs to measure some sort of action accurately the strain needs to be calculated accurately to compensate for deflection. Finally, strain can be useful in solving statically indeterminate problems. Equations 3 and 4 show how to calculate normal and shear strain.

(3)

(4)

Feedback and Recommendations

Name *
Subject *
email *
Comments *