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SDOF Natural Frequency & Damping Ratio Calculator

Single degree of freedom (SDOF) modal dynamics provides the core analytical foundation for structural vibration and mechanical shock analysis.

Oscillating lump mass.

Structural spring stiffness.

Viscous damping constant.

Calculated Result
3.18 Hz

Natural Frequency (fn)

Damping Ratio (ζ)

0.050 (5.0%)

Natural Period (Tn)

0.314 s

Damped Frequency (fd)

3.18 Hz

Vibration Regime

Underdamped (Oscillatory Decay)

Calculation Breakdown

  1. Step 1: Undamped Natural Frequencyωn = √(k / m) = √(40000 / 100) = 20.00 rad/s (3.18 Hz)
  2. Step 2: Damping Ratio Evaluationζ = c / [ 2·√(k·m) ] = 200 / 4000.0 = 0.050

What Is the SDOF Natural Frequency & Damping Ratio Calculator?

An SDOF system models an idealized dynamic structure whose configuration can be fully specified by a single displacement coordinate.

How Does the SDOF Natural Frequency & Damping Ratio Calculator Work?

Computes angular frequency ωn = √(k/m).

Computes critical damping coefficient cc = 2·√(k·m).

Calculates damping ratio ζ = c / cc.

Identifies vibration regime (underdamped, critically damped, or overdamped).

SDOF Natural Frequency & Damping Ratio Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

ωn = √(k / m), fn = ωn / (2π), cc = 2·√(k·m), ζ = c / cc, ωd = ωn·√(1 - ζ²)

Fundamental equations of motion for damped harmonic single degree of freedom oscillators.

How to Use the SDOF Natural Frequency & Damping Ratio Calculator

  1. Enter mass in kg and stiffness in N/m.
  2. Enter viscous damping coefficient in N·s/m.

Step-by-Step Example Calculation

Mechanical Equipment Isolation Mount

Input Values:

mass:100
stiffness:40000
dampingCoeff:200
Worked Steps: 100 kg machine on 40 kN/m spring mounts with 5% damping.

Understanding Your Result

Primary output reports natural frequency in Hz.

Summary displays natural period, damping ratio, and vibration regime.

Factors That Affect the Result

  • Stiffness-to-mass ratio.

When Should You Use This Calculator?

  • Vibration isolation, earthquake structural analysis, and machine balancing.

Assumptions & Limitations

  • Assumes linear elastic stiffness and linear viscous dashpot damping.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Exact analytical solution of second-order linear ODE.

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