Method for encapsulating a ceramic device for embedding in composite structures

A method for fabricating a ceramic actuator/sensor package, comprising the steps of:

• bonding wire leads to electrodes of a ceramic actuator/sensor;
• encapsulating the ceramic actuator/sensor in a non-conductive fiber composite material having a coefficient of thermal expansion between that of the ceramic material and a graphite-epoxy laminate in which the actuator/sensor may be later embedded;
• and
• placing, prior to encapsulation, a high-modulus graphite fiber material next to the actuator/sensor, with fibers extending in a direction transverse to a desired longitudinal direction of strain, and terminating adjacent to, but not in electrical contact with the ceramic, wherein the actuator/sensor characteristics are enhanced because the graphite material inhibits strain in the transverse direction;
• whereby the encapsulating material provides good mechanical coupling, reduces thermally induced stresses, electrically insulates the actuator sensor, and protects it from mechanical damage.

A method of embedding a ceramic actuator/sensor in a laminated structural member, the method comprising the steps of:

• bonding wire leads to electrodes of a ceramic actuator/sensor;
• encapsulating the ceramic actuator/sensor in a non-conductive fiber composite material to form an actuator/sensor package, the encapsulating material having a coefficient of thermal expansion between that of the ceramic material and the material of the laminated structural member;
• and
• embedding the actuator/sensor package at a selected location in the laminated structural member;
• whereby the encapsulating material provides good mechanical coupling to the structural member, reduces thermally induced stresses, electrically insulates the actuator/sensor, and protects it from mechanical damage before and during embedment.

A method for fabricating a ceramic actuator/sensor package, comprising the steps of:

• bonding wire leads to electrodes of a ceramic actuator/sensor;
• encapsulating the ceramic actuator/sensor in a non-conductive fiber composite material containing fiberglass cloth and epoxy, wherein the encapsulating step includes wrapping the ceramic actuator/sensor with the fiber composite material, and curing the encapsulated package at a suitable temperature, to harden the encapsulating material and produce a package with high mechanical stiffness and strength;
• and
• placing, prior to encapsulation, a high-modulus graphite fiber material next to the actuator/sensor, with fibers extending in a direction transverse to a desired longitudinal direction of strain, and terminating adjacent to, but not in electrical contact with the ceramic, wherein the actuator/sensor characteristics are enhanced because the graphite material inhibits strain in the transverse direction;
• whereby the encapsulating material provides good mechanical coupling, reduces thermally induced stresses, electrically insulates the actuator/sensor, and protects it from mechanical damage.

A method of embedding a ceramic actuator/sensor in a laminated structural member, the method comprising the steps of:

• bonding wire leads to electrodes of a ceramic actuator/sensor;
• encapsulating the ceramic actuator/sensor in a non-conductive fiber composite material to form an actuator/sensor package, wherein the encapsulating step includes wrapping the ceramic actuator/sensor with the fiber composite material;
• and
• embedding the actuator/sensor package at a selected location in the laminated structural member, by placing the package at its selected location between laminates of the structural member during fabrication of the member, and curing the composite structural member at an elevated temperature;
• whereby the encapsulating material provides increased stiffness and strength to the actuator/sensor package, provides electrical insulation for the actuator/sensor, and provides good mechanical coupling between the ceramic actuator/sensor and the structural member, with adhesive properties that survive the curing step.