Electromechanical damping: piezo shunt damping
Purpose and scope
Piezo elements used exclusively for structural damping
Function:
convert mechanical strain energy into electrical energy
dissipate energy in passive or semi-passive shunt networks
Piezo damping elements are not used as sensors
Sensing using piezo surface microphones is handled separately
Piezo damping elements
Type:
piezo ceramic disks (PZT)
Mounting:
bonded directly to steel structure
Placement strategy:
bonded at modal antinodes of the spindle tower
placement determined by:
modal analysis
experimental hammer testing
Number:
multiple elements distributed over dominant bending modes
Explicit locations:
spindle tower side plates
Not placed on:
spindle housing
spindle mounting plate
non-load-bearing panels
Shunt networks
Each piezo element connected to an electrical shunt
Shunt types:
resistive (R)
resistive-inductive (R-L), if required
Baseline damping:
passive
independent of software
Failure behavior:
defaults to fixed, known-good resistance
Instrumentation of shunts
Shunt circuits instrumented with:
piezo voltage measurement
piezo current measurement
ECU computes:
instantaneous electrical power
averaged dissipated power
Power data:
logged
visualized
used for tuning and validation
Adaptive shunt tuning
Shunt resistance adjustable via digital potentiometer
Tuning strategy:
slow supervisory loop
time scale: minutes
Algorithm characteristics:
small bounded resistance steps
comparison of dissipated power at neighboring settings
hysteresis and min/max limits
Purpose:
compensate for:
temperature changes
boundary-condition changes
structural aging
Adaptive tuning:
optional
fully disable-able
not required for baseline damping
Interaction with other damping strategies
Piezo shunt damping complements:
structural CLD (carbon fiber)
internal damping (epoxy granite)
Piezo damping targets:
specific structural modes
Not intended to:
replace passive damping
provide active vibration cancellation