An effective mesh is a mesh that provide you maximum accuracy in less computational time. If the mesh is very fine, the result will be accurate but the time taken to obtain the result will be more. Therefore, it is very important to make proper balance between number of elements in a mesh and computational time taken for analysis. In Autodesk Simulation Mechanical, to make proper balance between number of elements in a mesh and computational time taken for analysis, you can create fine mesh only in the region of high stress and strains by adding the refinement points. Below figure shows the a model with mesh with refinement points added.
