Railways NTPC (Technical Ability) Engineering Mechanics and Strength of Materials Question Bank Engineering Mechanics

  • question_answer
             A circular shaft is subjected to the combined action of bending, twisting and direct axial loading. The maximum bending stress \[\sigma \] maximum shearing stress \[\sqrt{3\sigma }\] and a uniform axial stress \[\sigma \](compressive) are produced. The  \[\sigma \] maximum compressive normal stress produced in the shaft will be:               

    A) 3\[\sigma \]                               

    B) 2\[\sigma \]         

    C) \[\sigma \]                                 

    D) Zero   

    Correct Answer: B

    Solution :

    \[{{\sigma }_{1,2}}=\frac{1}{2}({{\sigma }_{d}}+{{\sigma }_{b}})\pm \frac{1}{2}\sqrt{{{({{\sigma }_{d}}-{{\sigma }_{b}})}^{2}}+4{{\tau }^{2}}}\] \[=\frac{1}{2}(-\sigma +\sigma )\pm \frac{1}{2}\sqrt{{{(-\sigma -\sigma )}^{2}}+4\times 3{{\sigma }^{2}}}\] \[=0\pm \frac{1}{2}\sqrt{4{{\sigma }^{2}}+12{{\sigma }^{2}}}\] \[=\pm \,\,2\sigma \] Maximum compressive stress \[=2\sigma \]


You need to login to perform this action.
You will be redirected in 3 sec spinner