Research On Quantitative Detection Of Broken Wire Damage Of Wire Ropes Based On Magnetic Characteristics

As a key component of Engineering load-bearing,steel wire ropes are prone to various forms of mechanical damage in the use process,such as broken wire,wear,rust and so on.The occurrence of these damages will lead to the decrease of the safety load-carrying capacity of the wire rope.Therefore,it is necessary to carry out safety detection of the wire rope timely and evaluate its working state to ensure that the wire rope can always operate within the safe carrying range.Based on the principle of magnetic flux leakage testing,the quantitative detection of wire rope damage is carried out.In this paper,the quantitative detection of the wire rope damage is studied based on the principle of magnetic flux leakage detection.The residual strength of the wire rope is evaluated by the number of broken wires in the wire rope.The main contents of this paper are as follows.The excitation structure of the damage detector is simulated by finite element method,and the influence of the gap and the distance between magnets on the whole excitation circuit is analyzed.The finite element simulation analysis of the characteristics of the magnetic leakage field is carried out.The effects of the lift-off,the distribution of the broken wires,the fracture width and the number of broken wires on the magnetic leakage field are studied.The correctness of the theory of wire rope damage detection based on the leakage magnetic field characteristics is verified,The theory of damage detection for the wire rope based on magnetic flux leakage method is verified,which provides a reference for the structure design of damage detector.A test platform for the safety detection of wire ropes is built.In order to ensure that sufficient tension can be provided for the wire rope to be inspected,the strength strength design of the test platform is designed.In order to reduce the sensitivity of magnetic leakage field to lift-off,the magnetic concentrating ring was employed in the detector.The radial component detector and the axial component detector are designed respectively to detect the radial and axial components of the magnetic leakage field.According to the output characteristics of the detector,the signal pre-processing circuits of multi-channel output and single-channel output are designed respectively.The method of signal denoising based on wavelet transform is studied.Discrete wavelet transform,discrete wavelet packet transform and dual tree wavelet transform are applied to the damage signal.'sqtwolog','minimaxi','heursure','rigrsure' and neigh block are used to calculate the threshold.The effects of three signal transformation methods and five threshold calculation methods on denoising quality are compared horizontally.Finally,a method for the denoising of broken wires of the wire rope based on the combination of dual tree wavelet and neigh block threshold is proposed.The method of extracting characteristic information of the damage signal in time domain,frequency domain and time-frequency domain is studied.The classification effect of each characteristic parameter is compared horizontally by using the criterion of distance separability.A method of extracting characteristic parameters in time-frequency domain based on the combination of even wavelet packet and singular value is proposed.The quantitative identification model of broken wires of the wire rope based on machine learning is studied.The recognition effects of the three network models on broken wires are compared.After the research of signal denoising,feature extraction and quantitative identification,a quantitative detection model for broken wires of the wire rope based on DTCWPT,SVD and OSELM is proposed.In this paper,the key technologies in the process of quantitative detection of broken wires of the wire rope are studied based on magnetic flux leakage detection method.The modules of the detector design,the signal noise reduction,the feature extraction and the model establishment of quantitative identification are deeply studies,which provides reliable theoretical and methodological support for the development of damage detection system and products for the wire rope.