Issue34

Z. Jijun et alii, Frattura ed Integrità Strutturale, 34 (2015) 590-598; DOI: 10.3221/IGF-ESIS.34.65 597 The last three items in the formula above are respectively gradient, temporal item and stochastic noise of the average error. In this paper, 30 images of normal wire rope and 30 images of wire rope with fractures are used for the training of the neural network model, taking learning rate,  , as 0.1, and instant constant,  , as 0.85. The output of the wire rope with defect is 1, or otherwise, 0. At the beginning, weight is selected as the random number to meet normal distribution. Through the output results of the training set by statistics, the scope of the output threshold value can be identified. Fig. 12 shows the structure of the three layers of BP neural network, and Tab. 1 presents the results from the tests of the experimental groups. Figure 12: Structure of the three layers of BP neural network. No. State of wire rope Output of neural network 1 Surface damage 0.423 2 good 0.933 3 good 0.862 4 Surface damage 0.699 5 good 0.914 6 good 0.872 7 Surface damage 0.795 Table 1: Results from the tests of the experimental groups. Based on the actual state of the wire rope, and the corresponding output results of the neural network, this paper sets the output threshold value for identifying of the neural network model at 0.85. R ESULTS AND ANALYSIS o verify the effectiveness of the neural network model, the collected 60 original pictures of wire rope are input as test samples into the neural network model to identify the existence of fracture. There are 30 pictures of good wire rope and 30 with defect. Through the experimental analysis, the experimental results of wire rope test are shown in Tab. 2. State of wire rope Good wire rope Wire rope with defect Accuracy Good surface 27 3 91% Surface damage 2 28 93.3% Table 2: Detection results of wire rope. It can be seen from the results that the method proposed in this paper can reach a relatively high accuracy of the defect detection of surface of wire rope, yet some errors are inevitable. Through the analysis, it indicates that the good wire rope T