ENGINEERING DYNAMICS CW Aim The aim of this assignment is to carry out a structural vibration analysis of a physical system and to relate the vibration response to the assessment of structural integrity. Why are we asking you to do this? The skills you demonstrate in this assessment are important because structural fatigue failure is caused by cyclic stress and strain within structural members experiencing vibration. Through doing this assignment, you gain the experience of carrying out a complete and representative process of structural vibration analysis and structural integrity assessment for fatigue failure. This assignment utilises a range of tools that are widely used in industry and helps you to develop the knowledge, skills and good practice of engineering analysis that will enhance your employability for your future professional career. Task description For this assignment, you will carry out a torsional vibration analysis of a 3-rotor system (see figure 1) The dynamic behaviour of the system and the effects of system parameter variations on the dynamic properties are to be investigated using an integrated approach requiring the application of vibration theories, computer simulation and experimental testing. Figure 1 3-rotor test rig Task Details: 1. experimentally investigate the torsional vibration behaviour of the 3-rotor system and the effects of system parameter variations on the dynamic properties. See lab 3-rotor torsional vibrations . 2. establish an idealised torsional vibration model of the 3-rotor system and set up a 3-DOF mathematical model using the specified system parameters to derive the governing equations of motion. The excitation torque should be applied to the middle rotor as in the physical test. (Data for each individual student for carrying out this coursework are provided in Table 1.) 3. carry out modal analysis and sinusoidal response calculations by manual solution, determining the natural frequencies and the normal modes by the Matrix Iteration method and the steady state vibration response to a sinusoidal excitation torque using the Modal Superposition method. 4. carry out modal analysis and sinusoidal response simulations using MATLAB's built in functions 'eig' and 'ode45'. Verify the MATLAB program and the results using the manual solutions from (3). 5. simulate the vibration response to the specified swept sine excitation using the MATLAB program developed in (4) and estimate the Frequency Response Function (FRF) using the input/output signals. Refer to BS ISO 18431-1 and BS ISO 18431-2 and justify the methods and parameters used in data processing. 6. correlate the above computed FRF with the modal properties determined in (3) and (4). Examine the outcome of the correlation and suggest how the correlation may be improved with supporting evidence. 7. examine virtually the effect of one system parameter variation of your choice in a similar way to that in the physical test in (1), i.e., either (a) increase the mass moment of inertia of rotor A by 20% or (b) increase all torsional stiffness to three times of the original values. Compare the outcomes from (1) and (7) qualitatively. 8. determine the time history of the von Mises stress in each section of the shaft. Carry out a preliminary structural integrity assessment by predicting which section of the shaft will fail first due to fatigue. This process can be summarised using the flow diagram in Figure 2. Report Content You are required to submit an individual report for this assessment. All tasks in the Task Description section should be addressed. In addition, in the discussion section, the report should describe, compare and comment on the merits and limitations of the three different techniques used for structural vibration analysis (closed form solution, computer simulation and physical testing). Furthermore, describe two real world examples (quoting sources) and comment on the potentially damaging consequences of structural fatigue failures to the societies and communities that use and live near them. Report Structure and Style Follow the guidance on writing reports published in the Student Toolkit on the School of Engineering Students Moodle area. Your report should have the following sections: o Title o Abstract o Introduction o Literature survey o Theory, methods & results for each objective in the Task Description section o Discussion o Conclusion o Bibliography o References (see below) o Appendices InfoSkills Your report should include at least 3 references to support your design/conclusions, with at least one of each of the following types of reference (use the MMU Harvard style): 1. A published reference source in the University Library 2. A web reference (all types of media) 3. A technical reference source, e.g. manufacturer's datasheet, industrial standard, etc The University Library has an online tutorial to help you find good quality reference sources and a guide on how to use them correctly in your document using the MMU Harvard referencing style. Unit Learning Outcomes To pass this assessment your submission must demonstrate that you able to: ULO 2: work to appropriate British or European Standards and Codes of Practice ULO 4: construct valid simulation models of mechanical problems using industry standard software Graduate Learning Outcomes Your marks will be determined by the quality of your work, using the standard criteria for the following GLOs: GLO 1: Apply skills of critical analysis to real-world situations within a defined range of contexts GLO 2: Demonstrate a high degree of professionalism characterised by initiative, creativity, motivation and self-management GLO 6: Find, evaluate, synthesise and use information from a variety of sources GLO 7: Articulate an awareness of the social and community contexts within their disciplinary field