Estimating bolt tightness in non-slender bolts from vibrations

Recent research proposes a vibration-based approach for a more accurate estimation of bolt tension. The method applies the bolt’s transverse natural frequencies and relies on measurements obtained in two steps. The natural frequencies are measured with and without an additional boundary mass. If the boundaries are flexible, the natural frequencies will decrease when adding mass. The initial works assume slender bolts using Euler-Bernoulli theory, but in many industrial applications, bolts can be very non-slender. Recent work introduced the Timoshenko theory to accurately model non-slender bolts. This work, focus on symmetry. The procedure is adapted to symmetric non-slender bolts, using a boundary symmetric Timoshenko model. The issues arising from using this novel vibration-based method for non-slender bolts are addressed, the effect of the simplification in assuming symmetry is investigated, and improvements to the estimation
algorithm are introduced.