• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Vibration isolation is one of the methods by which engineers combat the problem of harmonic resonance. It is the purpose of this lab to investigate how the resultant force of vibrations acting in a mechanical device may vary

Extracts from this document...

Introduction

Dynamics & Control Vibration Isolation William Annal Reg: 200334440 Contents Introduction 3 Theory 3 Experimental Work: 5 Procedure 5 Measurements 5 Calculations 6 Results 6 Discussions & Conclusions 7 Appendices A 9 B 10 Introduction Vibration isolation is one of the methods by which engineers combat the problem of harmonic resonance. It is the purpose of this lab to investigate how the resultant force of vibrations acting in a mechanical device may vary according to the frequency of oscillation that the device is subjected to, and how this relates to the natural frequency of the device. Theory Harmonic Resonance is the condition under which a mechanical device or structure is subjected to vibratory oscillations, the frequency of which, match the natural frequency of the device or structure. Under such conditions extreme amplitudes of vibration may be achieved and in some circumstances the structure may literally be shaken or shake itself to pieces. Vibrations of relevance are categorised into three main types; Free or natural vibrations, forced vibrations and self-excited vibrations. Free or natural vibrations are a result of random disturbances and remain until they are damped by either the systems own internal or other friction forces. These vibrations depend on the systems own balance between elastic and inertial forces which act during the oscillation. ...read more.

Middle

Fig.3 As the shaft of the motor rotated the out-of-balance weights gave rise to a vibratory force that caused the test rig to oscillate. The vertical oscillations were measure by a transducer which was connected to the test rig. The transducer detected the vertical displacement by producing a voltage which was displayed on an oscilloscope. Measurements: Firstly, the voltage displacement transducer was calibrated using a slip gauge between the stylus of the displacement transducer and the base plate. The voltage change was observed on the oscilloscope on removal of the slip ring. This allowed a range of calculations to be undertaken using the output electrical signal properties. For a range of rotational speeds above and below resonance, the amplitudes of vibration were calculated. The rotational speeds were worked out using the sinusoidal oscilloscope trace as the time base settings were known. There measurements and calculated results were entered into the table available in appendix A. Also performed was a 'bump' or transient test. In this method the free or natural vibrations are measured by recording the 'transient' after striking the test rig. From the initial regular frequency of the transient, the natural frequency can be easily calculated. A wave form that was similar to the wave picture to the right, Fig 4 was observed on the oscilloscope. ...read more.

Conclusion

In general, stiff light systems have high natural frequencies whereas soft heavy systems have low natural frequencies. To change the natural frequency of the system you can add or subtract weight or you can stiffen or soften the structure. Excitation Response ? P =mr?^2 (N) 2*x FF=kx ? of Periods Scope Screen q*T (cm) Time Base (s/cm) Period T (s) Frequency 1/T (Hz) angular Velocity 2?/T (1/s) Scope Screen (cm) Scope Gain (V/cm) Volts Trans. Calib. (mm/V) mm Total Stiffness (N/mm) FF (N) 9 8.8 0.20 0.1956 5.114 32.130 5.317 3.8 0.1 0.38 1.85 0.703 22.9 8.05 13 9.6 0.20 0.1477 6.771 42.542 9.321 3.0 0.5 1.50 1.85 2.775 22.9 31.77 15 9.6 0.20 0.1280 7.813 49.087 12.409 5.4 1.0 5.40 1.85 9.99 22.9 114.39 12 9.8 0.10 0.0817 12.245 76.937 30.484 1.6 0.5 0.80 1.85 1.48 22.9 16.95 15 9.2 0.10 0.0613 16.304 102.443 54.047 3.0 0.2 0.60 1.85 1.11 22.9 12.71 20 9.7 0.10 0.0485 20.619 129.550 86.434 2.6 0.2 0.52 1.85 0.962 22.9 11.01 10 8.7 0.05 0.0435 22.989 144.441 107.446 2.5 0.2 0.50 1.85 0.925 22.9 10.59 11 8.7 0.05 0.0395 25.287 158.885 130.009 2.4 0.2 0.48 1.85 0.888 22.9 10.17 13 9.2 0.05 0.0354 28.261 177.568 162.382 2.3 0.2 0.46 1.85 0.851 22.9 9.74 14 9.4 0.05 0.0336 29.787 187.159 180.396 2.2 0.2 0.44 1.85 0.8066 22.9 9.24 Appendices ?? ?? ?? ?? 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Engineering section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Engineering essays

  1. Vibration Fault kit. Misalignment is a common cause of machinery malfunction. Considering the importance ...

    Conclusions Misalignment induced vibration is very complex. The data show that a machine can have parallel misalignment without exhibiting 2X vibration. Softer coupling seems to be more forgiving and tend to produce less vibration than a stiffer coupling. Misalignment vibration is a strong function of machine speed and coupling stiffness.

  2. Pulling things appart - The following experiment was designed to determine some of the ...

    Finally, we chose to investigate the family of nylons. Nylons are called polyamides, and thus are intrinsically related to Kevlar and Nomex. They therefore appeared to be a good place for us to continue our investigations. After investigating the properties of nylons, we discovered that there are many varieties of nylons, some of which agree with the mechanical properties of the white plastic, some of which do not.

  1. Thermofluid Mechanics and Mechanical Design lab report

    / (2x9.81) = 0.01594 m = 1.594 cm When r = 8cm = 0.08m Z= (9.322 x 0.082) / (2x9.81) = 0.02833 m = 2.833 cm When r = 10cm = 0.10m Z= (9.322 x 0.102) / (2x9.81) = 0.04427 m = 4.427 cm Station Z, cm (measured from vertical scale)

  2. hospital mannagement system

    Furthermore, as in prototyping, the increments provide feedback to the client that is useful for determining the final requirement of the system. 2.1.6 How we used this model for developing our project? > First task of our project begins with requirement analysis, in this task we are trying to understand what user asks and what he wants?

  1. tensile test

    The zero of the load scale was adjusted as required and then the lower jaws of the testing machine were connected to the specimen. The extensometer was also checked if it was functioning by applying a small load. Sequence of Operation a)

  2. Steel Reinforcement Tension Test

    As Young's modulus (E) equal to stress increment divided by strain increment. Where strain is a dimensionless number, the unit of the modulus of elasticity is the same as that of stress. Besides, the modulus of elasticity is a measure of the deformability of a material.

  1. The goal of this lab is to understand the dynamic parameters behind a second ...

    Second, when amplitude gets small, greater percentage of the encoder's reading would be composed of error. Thus the reading is taken near the beginning. 2.2.1 Finding the Natural Frequency By applying basic properties of oscillation, and , we can obtain the natural frequency of the system using the information collected in Table.2.2-1.

  2. The overall objective of this laboratory experiment is to investigate the effects of proportional, ...

    is given by the following Eq, 2.2: ln Mp = Eq. 2.2 Therefore, the damping ratio ? = 6.023195 x 10-2 2.1.2 Velocity Feedback and a Step input of 2000 Counts Figure 2.3:Step input of PI control algorithm with velocity feedback: 2.1.3 Velocity Feedback and No Step Input (Doubled kp)

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work