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Mechanical Engineering System Analysis: Vibration Analysis- Report Writing Assignment Help
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Internal Code: MAS7330
i. Address the analytical content and describe the process followed, so as to confirm your understanding of the test rig and the experiment. (15 marks)
ii. Present and evaluate the results generated during the test. Compare to theory wherever applicable.
iii. Discuss your results and relate their significance to the scenarios presented as well as to the design of any engineering system. Present your conclusions and recommendations. Include a discussion of possible errors (15 marks)
Your laboratory investigation should be based on the following stages:
A. Determine the stiffness of the spring to be used. This can be done by plotting a graph of the force versus the deflection.
B. Examine the free vibration of a rigid body and spring system with negligible damping. Disengage the dashpot damping unit from the beam. (manual, pages 17-19)
a. Observe and compare the vibration of the beam using the visual observation and a stopwatch and also using the chart recorder.
b. Why is accuracy improved if multiple measurements are taken and averaged? Which of the two methods in part a do you expect to be most accurate?
c. Compare with the analytical results you get based on calculations using the theoretical polar moment of inertia of the beam and motor and the spring rate of the system.
C. Examine the free damped vibrations of a rigid body and spring system. Re-engage the dashpot damping unit. Mark off four or five positions spaced along the beam, where it will be possible to station the damping unit, and measure the distance of these positions from the beam’s pivot point. Move the damping unit to each position in succession, and at each point perform two experiments: push the free end of the beam down and release it when the holes in the submerged dashpot damper disc plates are aligned (minimum damping), and when they are closed (effected by turning the top disc with respect to the bottom one). Record the resulting decay in the vibrations using the chart recorder. Work out the damping coefficient from the decay in amplitude of the free natural vibrations. Then, on the same set of axes, plot two curves of the damping coefficient against the square of the distance of the dashpot from the beam pivot point – one each for minimum and maximum damping. Discuss your findings. (manual, pages 20- 26, 53-54)
D. Examine the effect of damping on forced vibration, (forced damped vibration of a rigid body and spring system). (manual, page 27-32, 65-66) Make note that the exciter (i.e. unbalance) rpm is slower than the motor rpm by a gear ratio of 22/72.
a. Begin with the damper disengaged from the beam. Operate the motor at the natural frequency previously determined in part B. What does theory say about the amplification, and thus the motion, that should be expected?
b. Discuss the theoretical amplification factor and phase angle as the rig passes through resonance and compare with what you see in the test data.
c. Using the chart recorder and the rotating disk recorder on the motor, plot data, below, near, and above this natural frequency. Discuss the effects seen in the data with respect to the responses expected from theory.
d. Engage the damper to the beam at one of the mid-beam locations used in part E. Using the chart recorder and the rotating disk recorder on the motor, plot data, below, near, and above the natural frequency from part c. Discuss
the effects seen in the data with respect to the responses expected from theory.
Report Writing Assignment Help:
Task: Students will be given a scenario pertaining to the analysis of an engineering system. They will produce a technical report discussing their assessment of the scenario, including introduction, overview, objectives, appropriate calculations, conclusions, recommendations, and references. Section A (10 marks) Evaluate the importance of vibration analysis and the application of vibration isolation in the design/operation of a machine/vehicle/structure of your own choice. Read relevant vibration theory in order to describe how it is applied to the design/operation of the system. (?300 words.) Section B (15 marks) An engine has a total mass of 100 kg and is mounted on flexible supports which have a stiffness of 120 kN/m and include a viscous damper. The crankshaft of the engine has a mass of 30 kg with a centre of mass 2.5 mm from its axis of rotation. If the amplitude of vibration of the engine is 2 mm at resonant speed, calculate: i) The natural frequency of system vibration. ii) The damping coefficient of the flexible supports. iii) The force transmitted to the ground when the engine is running at its resonant speed. iv) The amplitude of vibration when the engine is running 20% faster than its resonant speed. v) The phase angle between the maximum disturbing force and the displacement when the engine is running 20% faster than its resonant speed. Section C Using the “Universal Vibration Apparatus”, (shown in the diagram below), and the associated “User Guide,” carry out a vibration analysis of a Rigid Body-Spring System to investigate the effect of viscous damping on the forced vibration of a cantilever beam arrangement.
i. Address the analytical content and describe the process followed, so as to confirm your understanding of the test rig and the experiment. (15 marks)
ii. Present and evaluate the results generated during the test. Compare to theory wherever applicable.
iii. Discuss your results and relate their significance to the scenarios presented as well as to the design of any engineering system. Present your conclusions and recommendations. Include a discussion of possible errors (15 marks)
Your laboratory investigation should be based on the following stages:
A. Determine the stiffness of the spring to be used. This can be done by plotting a graph of the force versus the deflection.
B. Examine the free vibration of a rigid body and spring system with negligible damping. Disengage the dashpot damping unit from the beam. (manual, pages 17-19)
a. Observe and compare the vibration of the beam using the visual observation and a stopwatch and also using the chart recorder.
b. Why is accuracy improved if multiple measurements are taken and averaged? Which of the two methods in part a do you expect to be most accurate?
c. Compare with the analytical results you get based on calculations using the theoretical polar moment of inertia of the beam and motor and the spring rate of the system.
C. Examine the free damped vibrations of a rigid body and spring system. Re-engage the dashpot damping unit. Mark off four or five positions spaced along the beam, where it will be possible to station the damping unit, and measure the distance of these positions from the beam’s pivot point. Move the damping unit to each position in succession, and at each point perform two experiments: push the free end of the beam down and release it when the holes in the submerged dashpot damper disc plates are aligned (minimum damping), and when they are closed (effected by turning the top disc with respect to the bottom one). Record the resulting decay in the vibrations using the chart recorder. Work out the damping coefficient from the decay in amplitude of the free natural vibrations. Then, on the same set of axes, plot two curves of the damping coefficient against the square of the distance of the dashpot from the beam pivot point – one each for minimum and maximum damping. Discuss your findings. (manual, pages 20- 26, 53-54)
D. Examine the effect of damping on forced vibration, (forced damped vibration of a rigid body and spring system). (manual, page 27-32, 65-66) Make note that the exciter (i.e. unbalance) rpm is slower than the motor rpm by a gear ratio of 22/72.
a. Begin with the damper disengaged from the beam. Operate the motor at the natural frequency previously determined in part B. What does theory say about the amplification, and thus the motion, that should be expected?
b. Discuss the theoretical amplification factor and phase angle as the rig passes through resonance and compare with what you see in the test data.
c. Using the chart recorder and the rotating disk recorder on the motor, plot data, below, near, and above this natural frequency. Discuss the effects seen in the data with respect to the responses expected from theory.
d. Engage the damper to the beam at one of the mid-beam locations used in part E. Using the chart recorder and the rotating disk recorder on the motor, plot data, below, near, and above the natural frequency from part c. Discuss
the effects seen in the data with respect to the responses expected from theory.