Free Engineering Tool
Accelerometer Mounting Resonance Calculator
Calculate the usable frequency range of your accelerometer based on mounting method. Compare stud, adhesive, magnet, and probe tip mounting effects on measurement bandwidth.
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Mounting Resonance Effect
Every accelerometer has a resonant frequency specified for ideal (stud) mounting. When using less rigid mounting methods, the system resonance drops because the mounting adds compliance (spring effect).
Where k is the mounting reduction factor, typically:
Mounting Methods — Typical Resonance Values
| Mounting Method | Typical Mounted Resonance | Factor k | Usable Range (at ±3 dB) |
|---|---|---|---|
| Stud mount | 28–32 kHz | 0.90–0.95 | ~10 kHz |
| Thin adhesive layer | 18–22 kHz | 0.60–0.70 | ~6–7 kHz |
| Adhesive pad (thick) | 12–16 kHz | 0.40–0.50 | ~4–5 kHz |
| Flat magnet | 6–8 kHz | 0.20–0.25 | ~2–2.5 kHz |
| Two-pole magnet | 3–5 kHz | 0.10–0.15 | ~1–1.5 kHz |
| Probe tip / hand-held | 1.5–2.5 kHz | 0.05–0.08 | ~0.5–0.8 kHz |
ℹ️ Rule of Thumb: Use only up to 1/3 of the mounted resonance frequency for measurements within ±3 dB accuracy. For ±1 dB, use only 1/5. For highest accuracy (±0.5 dB), use only 1/10.
Practical Recommendations
- Route-based monitoring: Magnet mount is common — acceptable for frequencies up to ~2 kHz (120,000 CPM)
- Permanent monitoring: Always use stud mount for maximum bandwidth and repeatability
- Quick checks: Probe tip is okay for low-frequency measurements (1× and 2× on slow machines)
- Bearing analysis: Requires stud or thin adhesive for high-frequency envelope detection
⚠️ Important: Sensor mass should be <10% of the structure mass at the measurement point. Heavy sensors on lightweight structures reduce mounted resonance further and can alter the vibration being measured.
The mounting resonance is the natural frequency of the combined sensor + mounting system. It is always lower than the sensor’s bare resonant frequency because the mounting introduces compliance (acts as a spring). This limits the usable frequency range of the measurement.
Near resonance, the sensor’s amplitude response rises dramatically — up to +30 dB at resonance itself. At 1/3 of resonance, the response is within approximately ±3 dB of flat, which is acceptable for most industrial measurements. For tighter accuracy, use 1/5 or 1/10.
Stud mount or thin adhesive (cyanoacrylate) are recommended for bearing analysis because high-frequency content (envelope/demodulation up to 10–20 kHz) must be captured accurately. Magnet mounts cut off too much high-frequency information.
Yes. Heavier sensors lower the mounting resonance. Also, if the sensor mass is significant relative to the structure (>10%), it mass-loads the structure and changes its vibration characteristics. Always choose the lightest sensor that meets sensitivity requirements.
Yes. Use a flat-bottom rare-earth magnet on a clean, flat, machined surface. Apply firm contact. Avoid paint or rust under the magnet. A flat magnet on a good surface can reach 7–8 kHz mounted resonance; a two-pole magnet on rough surface may only achieve 3 kHz.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
Professional accelerometers and vibration analyzers with stud, magnet and adhesive mounting options.
