oral jan 25

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Master of Science in Mechanical Engineering Politecnico di Milano Course of Machine Design 2 / Advanced Machine Design (Prof. S. Beretta) Oral test – 29.01.2024 • Write on your paper the Name, Surname and University ID number. • Save your pdf according your ID number Exercise 1 (3 pts) A steel beam inserted in a frame is subjected to a compressive force F and it is constrained by: i) an encastre at the base in the x-Z plane; ii) a simple roller at the midspan (only displacement along y is blocked) and iii) two rollers at the top end. The beam is then differently constrained comparing the two planes of symmetry of the column (x-z) and (y-z), as shown in the Figure. Q1: What is the length of the column, for which the limit load is plastic collapse? Q2: what is the admissible load when the length is 3600 mm? profile HE100B - E (Elastic modulus) = 206000 MPa Sy (Yield stress) = 500 MPa Beam profiles Axis yy Axis xx Linear mass Profile identification Axis yyAxis xx Exercise 2 (1pt) Express the relevant stress components for a scarf joint and how could you calculate the minimum thickness t of the metal sheet. Exercise 3 (2 pt) Calculate the radial contraction of the pressure vessel (aluminum alloy) under the effect of the external pressure p. External pressure p = 10 MPa Diameter D = 300 mm Wall thickness t = 8 mm E = 70000 MPa n = 0.3 Exercise 4 (2 pts) Considering the following expression that allows to describe the fatigue crack closure: If the effective crack threshold is DKth,eff = 3 MPaÖm, can you estimate DKth at the stress ratios R=0, R=-1 and R=-2 ? ADM, Lecture on FCG Crack propagation laws, Elber ),S(R,fS,)S-(S (a/w)fKΔ ysmaxopopmaxeff sp == wherea 3 ef f3 )KΔ( m C dN da=…