To be honest, I have yet to find a quality mass gainer on the market. The problem with most mass gainers is that they are loaded with cheap sugars as a carb source. Not only can this lead to greater fat gain, it can make drinking them several times a day unhealthy.
Mechanical stress: physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion.
Stress = Force / Area. Nominal stress : Force per unit area of cross section of a body on which the force is acting. However. If this is extremely high enough to cause the body to start deforming permanently i.e Plastic Deformation or Yielding, than such stress limit is termed as yield stress.