Introduction

What is Vibration?

1. Natural Vibration: Examples include tree branches swaying in the wind, ground undulations during earthquakes, in-place vibration of air molecules when sound propagates, and high-speed flapping of hummingbirds' wings.
2. Daily Life Vibration: Common instances are phone vibrations for incoming calls, shaking of washing machines during dehydration, jolts of vehicles on bumpy roads, swaying of swings, and vibration of plucked guitar strings.
3. Mechanical Equipment Vibration: Industrial machinery consists of rotating and moving components like motor rotors, bearings, gears, and couplings. During operation, factors such as rotational inertia, friction, eccentricity, or assembly errors cause periodic shaking—known as mechanical vibration. Under normal conditions, this vibration is regular and minimal; however, faults like component wear, imbalance, or misalignment alter its characteristics, forming the basis for fault diagnosis.

The Dual Nature of Vibration: Not All Vibration is Harmful

• Noise Pollution: Structural resonance generates noise, deteriorating the working environment.
• Equipment Damage: Prolonged vibration leads to loose bolts, bearing wear, and crack propagation.
• Production Downtime: Severe vibration triggers unplanned maintenance, resulting in economic losses.
• Safety Hazards: High-speed equipment may experience component ejection or structural fracture due to excessive vibration.

Key Parameters for Describing Vibration

• A = Amplitude
• f = Frequency
• (φ) = Phase

Three Manifestations of Vibration