1. Different measurement methods

There has been a strong need for non-destructive evaluation of tightening tension in screwed assemblies, with the aim of improving control of assembly processes and guaranteeing reliability. Indeed, even an assembly optimized with regard to the dimensioning of its fasteners will have a mediocre performance if the tightening tension control operation has been poorly carried out.

Portable or transportable instruments have been developed to meet these needs, and are now commercially available. They provide information (torque, tension, elongation, angle) on the quality of tightening achieved on an assembly.

There are various methods for checking tightness.

• Torque measurements

  The most widespread methods are those based on torque measurement. Even if the torque measurement...