Exam 2022 01 24 WT2

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Master of Science in Aeronautical Engineering Politecnico di Milano Course of Machine Design (Prof. M. Giglio) Written test 2 – 24.01.2022 Name: Surname: Polimi-ID: Do not write here TOTAL Instructions For each of the following 8 questions, select the right answer among those provided, by adding the symbol “x” as appropriate in the yellow colored cells. Correct answers correspond to “+1”, wrong answers to “-1” and no answers to “0”. 1) Insert Name, Surname, ID# 2) Provide answers 3) Save as pdf 4) Return by email to [email protected] Question # Text Yes 1 Which among the following statements on criteria for fatigue assessment is CORRECT:  The Gough-Pollard criterion can be only applied in presence of a stress state characterized by normal stress components in two directions  The application of Gough-Pollard or Sines criteria produces a v alid result only for monoaxial stress state  In presence of mean stresses, the Sines's criterion does not require to use the Haigh diagram  None of the above  No answer/Left blank Question # Text Yes 2 Consider a pressure vessel subject to repeated load-unload pressure cycles (pulsating from zero). Indicate which of the following is CORRECT:  When performing the fatigue assessment of a point of the wall, the fatigue limit only depends on the yield stress of the material  under certain assumptions, the fatigue assessment could be carried out using the Sines criterion on the internal point of the wall  The point in the middle of the thickness is the most critical for the fatigue assessment  None of the above  No answer/Left blank Question # Text Yes 3 Consider a portion of a thin aeronautical panel with a central crack, only subject to pulsating shear stresses (see Figure): tau = tau_0 * (1 + sin wt) Find the correct…