Fatigue Strength · Machine Design · GATE ME

The S-N curve from a fatigue test for steel is shown. Which one of the options gives the endurance limit?

Which of the following methods can improve the fatigue strength of a circular mild steel (MS) shaft?

A machine component made of a ductile material is subjected to a variable loading with $${\sigma _{\min }} = - 50MPa$$ and $${\sigma _{\max }} = 50MPa.$$ If the corrected endurance limit and the yield strength for the material are $$\sigma {'_e}$$ $$100MPa$$ and $${\sigma _y} = 300MPa,$$ respectively, the factor of safety is __________.

For the given fluctuating fatigue load, the values of stress amplitude and stress ratio are respectively.

Which one of the following is the most conservative fatigue failure criterion?

In a structure subjected to fatigue loading, the minimum and maximum stresses developed in a cycle are $$200$$$$MPa$$ and $$400MPa$$ respectively. The value of stress amplitude (in $$MPa$$) is ____________.

A rotating steel shaft is supported at the ends. It is subjected to a point load at the center. The maximum bending stress developed is $$100 MPa.$$ If the yield, ultimate and corrected endurance strength of the shaft material are $$300$$ $$MPa,$$ $$500$$ $$MPa$$ and $$200$$ $$MPa,$$ respectively, then the factor of safety for the shaft is __________.

In terms of theoretical stress concentration factor $$\left( {{k_t}} \right)$$ and fatigue stress concentration factor $$\left( {{k_f}} \right),$$ the notch sensitivity $$'q'$$ is expressed as

The $$S$$-$$N$$ curve for steel becomes asymptotic nearly at

A static load is mounted at the center of a shaft rotating at uniform angular velocity. This shaft will be designed for

The yield strength of a steel shaft is twice its endurance limit. Which of the following torque fluctuations represent the most critical situation according to Soderberg criterion?

Fatigue strength of a rod subjected to cyclic axial force is less than that of a rotating beam of the same dimensions subjected to steady lateral force because

In a shaft with a transverse hole, as the hole to the shaft diameter ratio ___________ (increases / decreases), the torsional stress concentration factor__________ (increases/decreases)

The process of shot peening increases the fatigue life of steel springs mainly because it results in

Stress concentration in a machine component of a ductile material is not so harmful as it is in a brittle material because

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

A thin spherical pressure vessel of $$200mm$$ diameter and $$1mm$$ thickness is subjected to an internal pressure varying from $$4$$ to $$8MPa.$$ Assume that the yield, ultimate and endurance strength of material are $$600,800,400MPa$$respectively. The factor of safety as per Goodman's relation is

A cylindrical shafts is subjected to an alternating stress of $$100MPa.$$ Fatigue strength to sustain $$1000$$ cycles is $$490MPa.$$ If the corrected endurance strength is $$70MPa,$$ estimated shaft life will be

A ductile material having an endurance limit of $$196$$ $$N/m{m^2}$$ and the yield point at $$294$$ $$N/m{m^2}$$ is stressed under variable load. The maximum and minimum stresses are $$147$$$$N/m{m^2}$$ and $$49$$$$N/m{m^2}$$. The fatigue stress concentration factor is $$1.32.$$ The available factor of safety for this loading is