Conductive knitted fabric as large-strain gauge under high temperature

An intrinsically conductive knitted fabric-based electrical resistive strain gauge is developed to measure in-plane or out-of-planar large strain under high temperature. Electro-mechanical properties, which governor the sensitivity of the gauge, are analyzed theoretically by a model of weft plain fabric. The contacting electrical resistance (R-c), resulted from two overlapped yams, is attributed to be the key factor contributing to the resistance-strain response while the fabric structure determines the sensitivity of the gauge. Two structures are fabricated making use of the properties of contacting resistance to find the key factors governing the sensitivity, repeatability and accuracy of the sensors. The effects of strain-rate and temperature on the sensitivity of the gauge are analyzed experimentally. From the experimental results, fabric gauges made from carbon fibers display a higher sensitivity, repeatability and accuracy than those made by stainless steel due to its small internal friction and intrinsic physics properties. Meanwhile, tubular structure has high maximum strain level than single warp structure but exhibits lower sensitivity than the latter. Temperature exhibits greater effect on the sensitivity than the strain-rate. (C) 2005 Elsevier B.V. All rights reserved.