Ing Ind - Inf (Mag.)(ord. 270) - BV (478) NUCLEAR ENGINEERING - INGEGNERIA NUCLEARE
095841 - MACHINE DESIGN 2
Ing Ind - Inf (Mag.)(ord. 270) - BV (483) MECHANICAL ENGINEERING - INGEGNERIA MECCANICA
095841 - MACHINE DESIGN 2
The main objective of the course is to provide the students with the necessary tools for the design and assessment of machine components, both under static and fatigue loading. The basics of mechanical design are upgraded in order to include advanced theory of elasticity, finite element analysis, design methods for static and fatigue loads (multiaxial and variable amplitude loading) and tools for assessing the influence of defects on static and fatigue strength. Theory of elasticity is extended in order to make it possible to evaluate stresses in typical mechanical components like pressure vessels, welded junctions, power transmission shafts, and validate finite element analyses.
Risultati di apprendimento attesi
The students will possess the knowledge of the main tools used for the design and assessment of machine components subjected to static and fatigue loading (knowledge and understanding).
Thanks to the practices that are focused on case studies, the students will improve the skills necessary for practical design application. The case studies include activities of laboratory tests and of Finite Element Method application, thus providing the capability to approach the solution of a problem with different tools (analytical, numerical and experimental), to understand their assumptions and limitations, and to analyse and critically discuss the results (applying knowledge and understanding; making judgements)
The final reports that the students are asked to write will improve the capability on writing a technical design report (communication skills).
Statically undetermined systems: Force Method
Axisymmetric problems: Thin and Thick Cylinders loaded by internal and external pressure and centrifugal loads.
Finite element modelling: basic formulation, definition of stiffness matrix, main shape functions, selection of element types, load and boundary conditions, evaluation of results, type of analysis (static, dynamic, etc.)
Strength of materials and assessment criteria
3D state of stress, multiaxial failure theories
Cyclic response of materials: High Cycle Fatigue. Endurance limit, Fatigue strength, Modifying factors, Stress Concentration and Notch Sensitivity, Multiaxial Fatigue, Variable Amplitude loading, Cumulative Fatigue damage
Linear Elastic Fracture Mechanics: energy approach (Griffith), Stress Intensity Factor, KIC, Fatigue Crack Propagation
Design of Machine Elements
Shaft and Shaft Components. Materials, layout, design for stress, deflections, critical speeds, components, fits.
Welding and the Design of Permanent Joints. Stresses in Welded Joints, Strength of Welded Joints.
The first case study will be based either on Railway Axle application or on a Power Transmission Gearbox application depending on the class. In both cases it will include General Analysis, Design of Shafts, Shrink Fits and Fatigue Assessment
The second case study will be a Pressure Vessel, with the Validation of Analytical Methods by Means of FEM analysis and Lab Tests.
Other case studies could be considered according with the availability of real mechanical problems to analyze.
The courses assumes that the students already possess the basic knowledge of Mechanics of Structures and Basic Machine Design, including kinematic analysis and solutions of beams, De Saint-Venant cases, 2D stress and strains analysis, stress concentration, failure theories and assessment under static loading.
Modalità di valutazione
The exam is based on a written test followed by oral one. Both of them are compulsory and cover all the topics of the course. The written test will include the solution of numerical exercises, aimed at assessing the capability of application of the design tools to practical cases and questions aimed at assessing the knowledge of the theoretical topics included in the program. The oral test will prove the capability of critically discuss the design tools and their limits and or applicability conditions.
N. E. Dowling, Mechanical Behavior of Materials, Editore: Prentice Hall, Anno edizione: 2013
J.E. Shigley et Al, Mechanical Engineering Design, Editore: McGraw-Hill, 9th Edition, Anno edizione: 2011
Lecture notes of the teacher available on Polimi Beephttps://beep.metid.polimi.it
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