A machine element has an ultimate strength $$\left( {{\sigma _u}} \right)$$ of $$600\,\,N/m{m^2},$$ and endurance limit $$250$$ $$\,N/m{m^2}.$$ The fatigue curve for the element on log-log plot is shown below. If the element is to be designed for a finite of $$10000$$ cycles, the maximum amplitude of a completely reversed operating stress is _________ $$\,N/m{m^2}.$$

In a structural member under fatigue loading, the minimum and maximum stresses developed at the critical point are $$50$$ $$MPa$$ and $$150$$ $$MPa,$$ respectively. The endurance, yield, and the ultimate strengths of the material are $$200$$ $$MPa,$$ $$300$$ $$MPa$$ and $$400$$ $$MPa,$$ respectively. The factor of safety using modified Goodman criterion is

A bar is subjected to fluctuating tensile load from $$20$$ $$kN$$ to $$100$$ $$kN.$$ The material has yield strength of $$240$$ $$MPa$$ and endurance limit in reversed bending is $$160$$ $$MPa.$$ According to the Soderberg principle, the area of cross-section in $$m{m^2}$$ of the bar for a factor of safety of $$2$$ is

A forged steel link with uniform diameter of $$30mm$$ at the centre is subjected to an axial force that varies from $$40kN$$ in compression to $$160kN$$ in tension. The tensile $$\left( {{S_U}} \right),$$ yield $$\left( {{S_y}} \right)$$ and corrected endurance $$\left( {{S_e}} \right)$$ strengths of the steel material are $$600MPa, 420MPa$$ and $$240MPa$$ respectively. The factor of safety against fatigue endurance as per Soderberg’s criterion is