Abstract: A pre-load monitor is arranged for use between a washer face of a fastener and a bearing surface of a fixture arranged to receive a portion of a shank of the fastener. The pre-load monitor, which can be in the form of a washer, includes a piezoelectric generator which generates the electrical power to measure, monitor and report the pre-load. The resulting electrical power produced is proportional to the pre-load and can be stored to provide the energy required to function electrical, electronic and communication circuits included in the washer. Alternatively, the pre-load monitor can be a half- or split ring (or a C-ring) constructed similarly to that of the washer, or the ring can be a two-piece gasket construction that includes an array of the washers.

Abstract: A pre-load monitor is arranged for use between a between a washer face of a fastener and a bearing surface of a fixture arranged to receive a portion of a shank of the fastener. The pre-load monitor, which can be in the form of a washer, includes a piezoelectric generator which generates the electrical power to measure, monitor and report the pre-load. The resulting electrical power produced is proportional to the pre-load and can be stored to provide the energy required to function electrical, electronic and communication circuits included in the washer. Alternatively, the pre-load monitor can be a half- or split ring (or a C-ring) constructed similarly to that of the washer, or the ring can be a two-piece gasket construction that includes an array of the washers.