The Influence of Substrate Stiffness on the Performance of a Magnetoelastic Bilayer Gas Flow Sensor

A bilayer sensor consisting of a stress sensitive magnetoelastic layer mounted onto a support substrate has been developed utilizing its change in curvature when subjected to gas flow forces. Two different materials, aluminium and HAVAR, with various thicknesses were used as the support layer to investigate the effect of bilayer stiffness on sensor sensitivity. Selection of the support layer was also important in determining the location of the neutral bending axis of the composite bilayer ensuring maximum stress sensitivity within the magnetic layer. Change in magnetic permeability proportional to stress was detected by measuring the inductance of a pickup coil positioned around one end of the bilayer sensor. The sensor was subjected to various airflow speeds and delivered consistent signal outputs for flow speeds up to 25 ms^-1 while proving to be extremely robust in turbulent conditions.