Vibration analysis unit 2
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This document discusses the basic concepts of vibration analysis for condition-based monitoring, focusing on measurement directions, phases of vibration, and various parameters like displacement, velocity, and acceleration. It explains how to choose appropriate parameters for different mechanical components and outlines common failure modes and relevant exercises. The content aims to educate on the fundamentals and applications of vibration monitoring in machinery health assessment.
Vibration analysis unit 2
- 1. VIBRATION ANALYSIS FOR CBM BASIC CONCEPTS – UNIT 2 BY DIBYENDU DE
- 2. VIBRATION MONITORING Degrees of Freedom? Degrees of Freedom determines the direction in which we measure vibration
- 3. Measurement direction - Horizontal, Vertical, Axial.
- 4. MEASUREMENT DIRECTION - HORIZONTAL, VERTICAL, AXIAL. Horizontal Vertical Axial Instrument
- 5. CONCEPT OF PHASE - 1 Masses C and D are in sync or are in-step That is they move together Hence the masses are vibrating in phase
- 6. CONCEPT OF PHASE – 2 While Mass X is now at the upper limit Mass Y is at the neutral position and moving downwards towards the lower limit Hence Masses X & Y are moving 90 degrees out of phase
- 7. CONCEPT OF PHASE – 3 While Mass A is now at the upper limit Mass B is at the lower limit Hence Masses A & B are moving 180 degrees out of phase
- 8. UNITS OF VIBRATION Displacement in Microns or Mils 1mil = 1/1000 inch Velocity in mm/sec or inch/sec Acceleration in meter/sec^2 or ‘g’ Frequency in CPM or Hz Hz x 60 = CPM
- 9. Vibration Energy Mass, Stiffness, Space Natural Frequency Motion Time Strain Kinetic Force Overall Time wave form Orbit Signatures Envelope Cepstrum Faults = Unbalance, Misalignment, Bearings, Product defect etc frequency Low Medium High d v a Spike Energy Patterns
- 10. VIBRATION - CAR ANALOGY Low Frequency Long period (T) High displacement Average Velocity Low Acceleration Medium Frequency Medium period (T) Average displacement Average Velocity Average Acceleration High Frequency Short period (T) Low displacement Average Velocity High Acceleration
- 11. VIBRATION Displacement: Sensitive to low frequencies. Good guide for imbalance, & other low frequency faults. Velocity: Has average sensitivity throughout the frequency range. Reasonably sensitive to imbalance, misalignment, looseness and rolling element bearing damage. Acceleration: Sensitive to high frequencies. Good for rolling element bearing damage.
- 12. EXERCISE – CHOOSE APPROPRIATE PARAMETER • Anti friction Bearings – velocity and acceleration • Gears • Journal Bearings • Bush Bearings • Pump casing • VFD shaft • Thrust bearing • Pipes and fluid flows
- 13. EXERCISE – CHOOSE APPROPRIATE PARAMETER & DIRECTION • Motor • Pump • Cooling Tower Fan • On steel and concrete structures • Foundations • Slow speed anti-friction bearing • Vibrating Screen • Steam Turbines
- 14. EXERCISE - FAILURE MODES – PARAMETER? Pitting of anti-friction bearings Wear out and/or clearances of journal bearings Lubrication starvation Unbalance, misalignment, looseness Screw wear out and shear of extruders Leakage of mechanical seals Gear teeth sheared from root Cavitation Cracks in shafts Cracks in structures
- 15. EXERCISE – THINK OVER THE QUESTIONS • Which is the weakest bearing? • Which direction is the weakest? • What might be the failure modes? • What would be the parameters? • What is the most important direction • What would be the most important technique? • What would define the health of the machine? FAN BEARING 6320 BEARING NU320 BEARING NU219 BEARING 6219 & NU219 BLOWER ASSEMBLY
- 16. THANK YOU FOR COMPLETING UNIT 2 CONTACT: FOR FACILITATED TRAINING DIBYENDU DE, EMAIL ID: DDE337@GMAIL.COM