In the real world all the structures are subjected to various stresses and strain, The module mechanics of materials gives an idea about traditional method of analyzing the stress and strain were it is the base of for various recent developed software like ANSIS. The factors to be considered like concepts of plasticity, strain energy, various 2D approximations, the concepts of theories of failures and thermal stresses are briefly under gone in this module. The Part-A assignment is about the debate on 2D approximation. As in the real world all structures are built up in 3D structures, to determine the various stresses and strains on these structures the easy and possible way is by converting from 3D into 2D geometry. where 2D approximation plays a vital role, Based on the various conditions the object is brought under any one of the following conditions like plane stress condition, plane strain condition or axis symmetric condition and then the results are calculated. The debate is about whether the result we get by 2D approximation is reliable or only by analyzing the 3D geometry gives the reliable result, the result we get from the 2D approximation is a compromise. The Part-B assignment is based on the pressure vessel where for the given material AISI 1040 cold drawn steel. The ultimate strength and yield strength has to be found initially then the thickness is to be determined. Based on the result it should be categorized under thick or thin cylinder. The hoop stress and circumferential stress is to be found out and by considering minimum values among stress allowable yield and ultimate strength. Then Mohr’s circle has to be drawn, were by using AUTO CAD2010 software it is constructed and finally stress transformation has to be determined. The Part- B assignment also includes the usage of MATLAB software. It is required to generate code for obtaining the thickness, stress and its transformations. The Part-C assignment is to construct the yield locus as per the theories of failures-Maximum principal stress criteria by considering the given two principal stresses by substituting these stresses in formula yield surface and yield locus can be determined and also criteria for failure is determined. By using AUTO CAD2010 software yield locus is constructed and comparing it with the yield strength of material to cross check whether the object is subjected to safe working load or not.