Sine vibration ke specifications ko define karte waqt velocity ke form mein na dene ke kaaran technical aur practical aspects se jude hain. Main reasons yeh hain:
- Acceleration as Primary Parameter: Vibration testing mein acceleration (g ya m/s²) ko primary parameter maana jata hai kyunki:
- Acceleration directly system pe applied force se related hota hai (F = ma). Force aur stress analysis ke liye acceleration zyada relevant hai.
- Accelerometers, jo vibration measure karte hain, directly acceleration ko sense karte hain, toh testing equipment aur standards acceleration-based hote hain.
- Industry standards (jaise MIL-STD, ISO, ASTM) bhi acceleration ke terms mein define kiye jate hain, jo consistency deta hai.
- Velocity ka Limited Use: Velocity (mm/s ya m/s) vibration ka ek derived parameter hai aur yeh specific applications mein useful hota hai, jaise:
- Machinery health monitoring (e.g., bearing ya rotating equipment analysis), jahan velocity vibration severity ka achha indicator hota hai.
- Lekin sine vibration testing mein, velocity directly system ke dynamic response ya structural integrity se related nahi hota jitna acceleration hota hai.
- Frequency Dependency: Sine vibration ek single frequency pe hoti hai, aur velocity aur displacement frequency ke saath change hote hain:
- Velocity = Acceleration / (2π × frequency)
- Displacement = Acceleration / (2π × frequency)²
- Is wajah se, acceleration constant rakha jata hai kyunki yeh frequency se independent hota hai aur specification define karna simpler hota hai. Velocity specify karne se specification frequency ke saath complicated ho jati hai.
- Practicality in Testing: Vibration test systems (shakers) acceleration-based control systems use karte hain. Acceleration ko directly control aur measure karna easier hai compared to velocity, jo frequency ke saath vary karta hai.
- Stress aur Fatigue Analysis: Structures ya components pe vibration ka effect (stress, fatigue) acceleration se zyada directly correlate karta hai. Isliye sine vibration specs acceleration mein dena zyada practical aur meaningful hai.
Example:
Agar ek sine vibration test mein 10g acceleration at 200 Hz diya jaye, toh velocity calculate kar sakte hain:
- Velocity = 10 × 9.81 / (2π × 200) ≈ 0.078 m/s.
Lekin agar frequency change ho (e.g., 100 Hz), velocity bhi change ho jayega (0.156 m/s), jabki acceleration same rahega. Isse specification complex ho jati hai.
Conclusion:
Velocity ke form mein specs na dene ka reason hai ki acceleration simpler, frequency-independent, aur directly force/stress se related hota hai. Industry standards aur testing equipment bhi acceleration-based hote hain, isliye sine vibration specs acceleration mein hi define kiye jate hain. Agar velocity critical hai (jaise machinery monitoring), toh uske liye alag standards use hote hain.