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Free Engineering Tool #066

Damping Ratio Calculator

Determine damping ratio ζ from logarithmic decrement (successive peak amplitudes) or half-power bandwidth method. Supports multi-cycle averaging.

Log DecrementHalf-Power BandwidthAuto-Calc
Quick presets

Results

Damping Ratio ζ
Damping (%)
Log Decrement δ / Bandwidth Δf
Quality Factor Q
Damping Classification

Logarithmic Decrement Method

Half-Power Bandwidth Method

Quality Factor

Example — Log Decrement

Given: x₁ = 10 mm, x₂ = 6 mm, n = 1 cycle

δ = (1/1) × ln(10/6) = ln(1.667) = 0.5108

ζ = 0.5108 / √(4π² + 0.5108²) = 0.5108 / 6.304 = 0.0811 (8.11%)

⚠️ Note: The log decrement approximation ζ ≈ δ/(2π) is accurate to within 1% for ζ < 0.1. For higher damping, use the exact formula.

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Damping ratio from log decrement and half-power bandwidth. Last updated: February 2025

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Nikolai Shelkovenko

Nikolai Shelkovenko

Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.

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