A fixed-gear it is single speed like bicycle (or fixed-wheel bicycle, sometimes known as a fixie) is a bicycle that has no freewheel, meaning it cannot coast, as the pedals are always in motion when the bicycle is moving.
In a biaxial stresses there are two stresses in two dimension say (x,y) and caused shape deformation , but in a triaxial stresses there are three stresses in three dimension say(x,y,z) and caused volumetric deformatio.
A biaxial state of stress is defined as a state of stress where one of the three principal
stresses is equal to zero: σ1 ≠ 0 , σ2 ≠ 0 , σ3 = 0
A triaxial state of stress is defined as a state ...