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.
Tensile stress is the stress state caused by an applied load that tends to elongate the material in the axis of the applied load, or in other words, the stress caused by pulling the material. The strength of structures of equal cross-sectional area loaded in tension is independent of the shape of the cross section.