Exam 2024 06 21 WT1 text

Pagina 1

Exercise 1. Consider the hand chank power generator in Figure 1. T he hand chank with the motivated gear is concerned here. The external forces, F at point A, and P at Point O, middle point of A and B can be found during serving. The motivated gear is suffered the reaction force G from the internal system, which is fixed and constant in space and has a direction parallel to the axis x , P is rotating in space together with the structure, constant in magnitude and represented parallel to the x axis direction in Figure 1, F is rotating in space together with the structure, constant in magnitude and represented parallel to the y axis direction in Figure 1. The P and F are always coupled together in the same angle in space. All the beams are made by the material presented in the Table below with the diameter of the cross-section equal to 𝑑𝑑𝑏𝑏. Figure 1 Considering the structure is currently rotating at a constant angular speed ω, it is required to: 1. Determine the value of the external force P. 2. Plot the bending moment and torque diagrams neglecting axial and shear forces. 3. Perform the static assessment for the inner structure at section D. 4. Perform the fatigue assessment at section E. Data: Loads Fatigue and notch parameters for section E: 𝑏𝑏2 = 0.85 𝐺𝐺= 600 𝑁𝑁 𝑏𝑏3 = 0.85 𝐹𝐹= 100 𝑁𝑁 𝑞𝑞= 0.90 𝐾𝐾𝑡𝑡𝑓𝑓= 1.5 (for corner and support) Geometry 𝐾𝐾𝑡𝑡𝑡𝑡= 1.4 (for corner and support) 𝐶𝐶𝐶𝐶= 20 𝑚𝑚𝑚𝑚 𝐶𝐶𝐷𝐷= 𝐺𝐺𝐷𝐷= 70 𝑚𝑚𝑚𝑚 𝐵𝐵𝐶𝐶= 500 𝑚𝑚𝑚𝑚 Material: 𝑑𝑑𝑅𝑅= 200 𝑚𝑚𝑚𝑚 (diameter of the gear) 𝜎𝜎𝑈𝑈𝑈𝑈𝑈𝑈= 1800𝑀𝑀𝑀𝑀𝑀𝑀 𝐴𝐴𝐵𝐵= 160 𝑚𝑚𝑚𝑚 𝜎𝜎𝑦𝑦= 1200𝑀𝑀𝑀𝑀𝑀𝑀 𝑑𝑑𝑏𝑏 = 10 𝑚𝑚𝑚𝑚 Politecnico di Milano - Master of Science in Aeronautical Engineering Academic year 2023-24 Course of Machine Design (Prof. M. Giglio) Written test 1 – June 21, 2024 NAME : SURNAME : Polimi-ID : Do not write here: 1 2 3 Total Exercise…