In classical linear elasticity, when modeling a force/load boundary condition, it appears that we could either:
Use a pure Neumann boundary condition, where the 3 traction components are specified. In 3-D the 2 tangential traction components would be zero, with the non-zero component being the normal component.
Use a mixed boundary condition. Here, the 2 tangential traction components would be zero. The normal traction component is unknown. However, the normal displacement is now known, and the 2 tangential displacements are unknown.
Is it correct to say that 1 and 2 are both accurate methods of modeling this force boundary condition?
Is there an actual analytical expression for converting the 1 to 2?
If we know the normal traction component, could we actually uniquely convert this to a normal displacement value?