Abstract: A method and apparatus for pre-straining a bolt-on strain sensor. The pre-strain is preferably adjusted by inserting a strain adjusting tool through strain adjusting holes in the sensor and the structural member. The portion of the tool engaging the sensor is preferably offset from the portion of the tool engaging the hole in the support structure to provide a camming function. After the strain has been adjusted to a desired value, a bolt adjacent the strain adjusting hold of the sensor is tightened to fixedly secure the sensor to the support structure and maintain the preadjust strain at the desired value.

Abstract: A bolt-on strain sensor includes an L-shaped sensor body having a mounting hole formed at the end of each leg of the L-shaped body and a mounting hole formed at the intersection of the legs. A first strain sensing structure is formed in the sensor body between two of the mounting holes and a second strain sensing structure is formed in the sensor body between the other two mounting holes. The strain sensing structure is preferably a strain gauge instrumented measurement beam connected to the sensor body on opposite sides of the strain sensing region by spaced apart interconnecting members. A printed circuit board on which a plurality of electrical components are mounted is secured to the sensor body with a suitable fastener. A cover is then placed over the sensor body and printed circuit board.