Meaning
Numerical values that quantify the ability of a substance to convert mechanical pressure into electrical signals govern the sensitivity of sensors. A piezoelectric coefficient determines the amount of charge generated for every unit of applied force. It is a primary parameter for the design of ultrasound transducers and fuel injectors.
These values vary depending on the direction of the stress relative to the crystal axes.
Coupling Magnitude
Efficiency of the energy conversion is measured by the ratio of stored electrical energy to total mechanical work. The piezoelectric coefficient must remain stable over the entire operating temperature range. If the value drifts, the calibration of the device is lost.
Voltage Sensitivity
Response of the material to an external field is used to create precise movements in actuators. Within a production run, each piezoelectric coefficient is audited to ensure it meets the required tolerance. Variations in the demonstrated rate of response lead to uneven performance in multi element arrays.
Material Response
Strain produced by an applied voltage is calculated using these constants. When a piezoelectric coefficient is high, the actuator can provide larger displacements for a given input. Calling a design ready for production without characterizing the full tensor leads to unexpected vibration modes.
Performance is measured against the theoretical maximum for the crystal class.
