Strain Gage Measurements on Plastics and Composites

The bonded resistance strain gage, which is central to the topics treated here, was invented in the late 1930's and is now at about the mid-century mark in its career. During the first fifty years of its existence, the strain gage has been applied to virtually every known load-bearing material – ranging from asphalt to zirconium, and missing few, if any, of the letters in between. Whether the material be natural or man-made, metallic or nonmetallic, organic or inorganic, elastic or inelastic, someone has likely perceived the need to measure the surface strains resulting from applied loads. By far the most common way of doing so has been, and still is, the resistance strain gage.