Imagine a cantilever beam modelled with solid elements in FEA. Now, I want to apply loads to it in X, Y and Z axis. First option is to apply the load altogether, and then observe the results after it reaches equilibrium. Second option is that I can first apply the complete load along X axis, body reaches equilibrium, then I apply the complete load in Y axis, again body reaches equilibrium and then finally I apply the load in Z axis.
Can just anyone tell me that should the displacements, strains, stresses etc should be the same for the first case as compare to the second case?
I talked with some people and few of them say that it should be the same because ultimately, the total load that you are applying at the end of final equilibrium is the same, so it shouldn't make a difference. Furthermore, the method of superposition directly alludes that the results arising from one loading condition can be added on top of arising from other loading conditions.
However, others say that it shouldn't be the same because the stiffness of the structure changes while you apply the load. If you apply the complete X axis load first, then the final stiffness of the structure will be different, onto which you now will apply the load in Y direction, and subsequently in the Z direction. So the final results such as deformations, strains and stresses shouldn't be the same as compare to the case where you were applying the load together at the same time.
Which one is true? A comprhensive elaboration will be extremely appreciated.