Processing Magazine

Economical sensor film measures stress distribution on fasteners and bolts

November 18, 2009

The film is used to assess pressure magnitude and distribution between any two mating or impacting surfaces. The film is a valuable aid in both the manufacture and design of bolted joints and fasteners. The thin sensor film reveals how force is disbursed in bolted assemblies, gasketed and flanged interfaces. When placed between impacting or mating surfaces, the sensor film instantaneously and permanently changes color. The intensity of this color is proportional to the amount of pressure applied, allowing the user to quantify the stress characteristics across the surface. Applications exist for manufacturing process control and machine/component inspection and calibration. The sensor film’s spatial resolution is fine enough to expose minute surface defects and fatigue marks. With a gauge of only four to eight mils, the sensor film is thin and flexible, making it ideal for environments that cannot accommodate traditional load cells and other transducers. It can be hand or laser-cut to any size or dimension.