The invention relates to the technical field of pretightening force monitoring, in particular to an online monitoring method for pretightening force of a bolt in a steel
pipe. The method comprises the following steps: firstly, acquiring an original
digital signal sequence based on an acquired electromagnetic
resonance signal and an
acoustic reflection signal, preprocessing and intercepting to obtain a
time sequence fragment set, introducing a structure kernel mapping coding mechanism, and constructing a structural
feature set; then, based on the structural
feature set, constructing an asymmetric
topological graph, calculating local topological disturbance intensity of nodes, and converting the local topological disturbance intensity into a topological
tension field of a
time domain; based on the preprocessed
digital signal sequence, obtaining a structure kernel feature of the preprocessed
digital signal sequence, calculating a structure disturbance quantization quantity, obtaining a disturbance inversion structure response function in combination with a topological
tension field of a
time domain, and calculating an actual pre-tightening force predicted value; and finally, correcting the actual pre-tightening force predicted value to obtain a monitoring result. The technical problem of non-contact, continuous and high-precision on-line monitoring of the pretightening force of the bolt in the closed steel
pipe is solved.