Constrained-Layer Damping
Canonical Definition
Constrained-layer damping uses a viscoelastic layer bonded between a vibrating substrate and a constraining layer. Relative deformation shears the viscoelastic material and dissipates part of the vibration energy as heat.
What CLD Does And Does Not Do
| Job | CLD result |
|---|---|
| Reduce structural resonance and ring-down | yes, when coupled to the active mode in its useful temperature and frequency range |
| Block airborne road noise | not as a complete barrier system |
| Stop two trim parts touching | use repair or decoupling at the contact |
| Stiffen a weak load path | use structure, bracing or a better joint |
Why Universal Coverage Rules Fail
Performance depends on panel geometry, supports, mode shape, substrate stiffness, constraining layer, adhesive bond, temperature, frequency, and treatment placement. A fixed 25, 50, or 100 percent coverage claim cannot predict every panel. Treat high-motion regions first, then measure.
Application Contract
- Identify the resonant panel and operating condition.
- Record substrate and surface preparation.
- Record material, thickness, mass, constraining layer and application temperature.
- Roll or press to the specified bond condition.
- Keep drains, seams, fasteners, sensors and service points open.
Verification
Use a repeatable tap, shaker, speaker excitation, accelerometer, laser, or acoustic measurement. Compare resonant frequency, amplitude, ring-down and temperature. Inspect adhesion after thermal cycling and vehicle use.