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.
but the nominal stress (or engineering stress) is stress measure which gives us the quantity of stress at any point on the stress strain diagram and while calculating the nominal stress we use the original area not the current area of the material.