Lab 5 ammortizzatore relazione

Page 1

Politecnico di Milano Dipartimento di Ingegneria Aerospaziale Impianti e Sistemi Aerospaziali shock absorber PROJECT Sizing calculation damper of a Dassault Falcon 900 Giovanni V. July 2013 1 1. Introduction This report presents the design of a damper on a Dassault Falcon 900. The adjacent figure shows the type of damper used. 2. Contents 1. Introduction 1 2. Contents 1 3. List of symbols 2 4. Description of problem and solving method 3 4.1 Analytical expression of the reaction 3 4.2 Sizing 3 4.3 Sizing holes of leakage 3 4.4 Performance 4 5. Problem data 5 6. Calculations and results 5 6.1 Sizing 5 6.2 Sizing holes of leakage 5 7. Summary results 8 2 3. List of symbols 4. Description of problem and solving method 4.1 Analytical expression of the reaction To calculate the analytical expression of the reaction to the balance of the forces acting on the piston, resulting: On balance (light diaphragm) Therefore: You can consider as more than the pressure losses due to the change of section: . Then Making explicit and is the analytical expression of the reaction: 4.2 Sizing To size the damper, considering the maximum load factor allowed by law and based on this computing, the maximum reaction in relation to the ground. You dimension based on these results is the core area of the cylinder of the shock. With the formula: you can calculate the stroke of the damper, and then, considering an adiabatic process with you can calculate the remaining amount as the volumes of oil content or the length of the damper, using: . 4.3 Sizing holes of leakage The sizing of the holes leakage refers to the analytical expression of the reaction, in particular: from this we can derive the area of the hole. 3 4.4 Performance In the calculation of the total reaction, we can distinguish two…