Unit

Code	A005755
CFU	5
Teacher	Luca Landi
Teachers	Luca Landi
Hours	40 ore - Luca Landi
Learning activities	Affine/integrativa
Area	Attività formative affini o integrative
Sector	IIND-03/A
Type of study-unit	Opzionale (Optional)

STRUCTURAL RELIABILITY AND DURABILITY

Code	A005756
CFU	4
Teacher	Filippo Cianetti
Teachers	Filippo Cianetti
Hours	32 ore - Filippo Cianetti
Learning activities	Affine/integrativa
Area	Attività formative affini o integrative
Sector	IIND-03/A
Type of study-unit	Opzionale (Optional)
Language of instruction	Italian
Contents	Module B “Affidabilita' strutturale e durabilita'” of the “Progettazione Robusta” course aims to provide fundamental notions on the reliability assessment of fatigue strenght on complex random processes and calculation methods for their adoption (MATLAB language will be adopted for the exercises part of the course)
Reference texts	Teacher's notes Shigley J.E., Mischke C.R., “Mechanical Engineering Design”, Ed. McGraw-Hill, Inc. Collins J.A., “Failure Of Materials In Mechanical Design”, John Wiley & Sons Dahlberg T., Ekberg A., ”Failure Fracture Fatigue: An Introduction”, Studentlitteratur, Lund Matlab Manuals
Educational objectives	The student will acquire knowledge and skills in the field of signal analysis and in the field of fatigue behavior assessment of components subjected to mono and multi-axial stress states expressed in time and frequency domains (PSD). The student will therefore acquire the ability to reconstruct the probability density function and probability of a time signal and to extract from it the load spectrum of the alternating component of the cycles by means of counting methods in the time domain. Furthermore, the student will be able to obtain the representation of the FFT and the power spectral density function (PSD) in the frequency domain of a time-varying signal. The student will also acquire the ability to generate load histories in the time domain starting from their FFT and PSD frequency representations. The student will also be able to estimate the load spectrum of the alternating component of the cycles of a signal represented exclusively in frequency by its PSD. Finally, the student will be able to manage a multi-axial stress state time-varying or represented in frequency (PSD) in order to evaluate the fatigue strength of a component.
Prerequisites	To understand and be able to apply most of the techniques described in the course, preliminary knowledge of “Costruzione di Macchine” is required (Bachelor's Degree in Mechanical Engineering)
Teaching methods	The module is organized in: • classroom lectures during which the topics covered in the course are addressed. • in parallel, classroom exercises will be carried out using MATLAB numerical language All the teaching material used during the course is available through the Unistudium platform.
Other information	Further information is available through the Unistudium page of the course. The teacher is available for consultations at the end of each lesson; consultations with the teacher in person or through the Microsoft Teams platform can also be arranged at other times.
Learning verification modality	The exam for the “Progettazione Robusta” course, of which the “Affidabilità strutturale e durabilità” module represents module B, includes an oral test aimed at verifying knowledge of all the topics covered in the two modules.
Extended program	Signal analysis Notes on signal analysis. Deterministic processes and Fast Fourier Transform. Random processes and power spectral density (PSD). Theoretical definitions. Uniaxial fatigue (S-N). Recall and insights into uniaxial fatigue. Reliability of strength curves. Load spectra. Evaluation of equivalent load spectra. Definition of the so called “fattore di spettro” (spectrum factor). Cycle counting methods in the time domain. Reconstruction of load spectra from PSD functions in the frequency domain. Dirlik formula. Evaluation of the damaging power of loads, forces and accelerations. Uniaxial fatigue (E-N). Introduction and definition of the resistance curve. Neuber formula Multiaxial fatigue (S-N) Engineering approach to the problem of evaluating the strength of a component subjected to a multiaxial state of stress in time and frequency.
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