Abstract:A method is presented to demonstrate the use of artificial neural networks (ANNs) in
providing additional information regarding defects or flaws when used in conjunction with the
ultrasonic A-scan method. ANNs were employed both as pattern classifiers and as function
approximators to maximise the amount of data available from the temporal A-scan signal. A steel
bar was modelled in 2D using ABAQUS finite element analysis (FEA) software. A single defect
was introduced to the bar, modelled as a void, and parametr… Show more
“…Petrucci and Zuccarello [2] presented a fatigue damage formula in the form shown in equation (16). (16) The function are also functions of the spectral moments mi, i=0,1,2 and 4 , the parameter = / derived from the use of the Goodman's formula for accounting for the effect of mean stress. Smax is the maximum stress in the stress history, and k is a fatigue material property.…”
Section: Mean Stress Effect In Frequency Domain Fatigue Analysismentioning
confidence: 99%
“…This paper presents an alternative approach to those reviewed in the foregoing. Artificial neural networks have been known to provide greater scope for non-linear generalisation and have the ability to deal with a large number of input variables than direct application of optimisation methods [15], [16], [17]. The paper presents an artificial neural network frequency based approach for the analysis of random loading fatigue problems including the effect of mean stress.…”
The effect of mean stress is a significant factor in design for fatigue, especially under high cycle service conditions. The incorporation of mean stress effect in random loading fatigue problems using the frequency domain method is still a challenge. The problem is due to the fact that all cycle by cycle mean stress effects are aggregated during the Fourier transform process into a single zero frequency content. Artificial neural network (ANN) has great scope for non-linear generalization. This paper presents artificial neural network methods for including the effect of mean stress in the frequency domain approach for predicting fatigue damage. The materials considered in this work are metallic alloys. The results obtained present the ANN method as a viable approach to make fatigue damage predictions including the effect of mean stress. Greater resolution was obtained with the ANN method than with other available methods.
“…Petrucci and Zuccarello [2] presented a fatigue damage formula in the form shown in equation (16). (16) The function are also functions of the spectral moments mi, i=0,1,2 and 4 , the parameter = / derived from the use of the Goodman's formula for accounting for the effect of mean stress. Smax is the maximum stress in the stress history, and k is a fatigue material property.…”
Section: Mean Stress Effect In Frequency Domain Fatigue Analysismentioning
confidence: 99%
“…This paper presents an alternative approach to those reviewed in the foregoing. Artificial neural networks have been known to provide greater scope for non-linear generalisation and have the ability to deal with a large number of input variables than direct application of optimisation methods [15], [16], [17]. The paper presents an artificial neural network frequency based approach for the analysis of random loading fatigue problems including the effect of mean stress.…”
The effect of mean stress is a significant factor in design for fatigue, especially under high cycle service conditions. The incorporation of mean stress effect in random loading fatigue problems using the frequency domain method is still a challenge. The problem is due to the fact that all cycle by cycle mean stress effects are aggregated during the Fourier transform process into a single zero frequency content. Artificial neural network (ANN) has great scope for non-linear generalization. This paper presents artificial neural network methods for including the effect of mean stress in the frequency domain approach for predicting fatigue damage. The materials considered in this work are metallic alloys. The results obtained present the ANN method as a viable approach to make fatigue damage predictions including the effect of mean stress. Greater resolution was obtained with the ANN method than with other available methods.
“…In previous works [2][3][4][5][6], the same methodology was followed and synthetic data was only used. In this works few experimental results were introduced.…”
Section: Discussionmentioning
confidence: 99%
“…In a previous papers [2,3,4,5,6], the dynamic response has been used for this purpose. The propagation of elastic waves was considered in [2].…”
Abstract.A computational inverse technique was used in the localization and classification of defects. Postulated voids of two different sizes (2 mm and 4 mm diameter) were introduced in PMMA bars with and without a notch. The bar dimensions are 200x20x5 mm. One half of them were plain and the other half has a notch (3 mm x 4 mm) which is close to the defect area (19 mm x 16 mm).This analysis was done with an Artificial Neural Network (ANN) and its optimization was done with an Adaptive Neuro Fuzzy Procedure (ANFIS). A hybrid data base was developed with numerical and experimental results. Synthetic data was generated with the finite element method using SOLID95 element of ANSYS code. A parametric analysis was carried out. Only one defect in such bars was taken into account and the first five natural frequencies were calculated. 460 cases were evaluated. Half of them were plain and the other half has a notch. All the input data was classified in two groups. Each one has 230 cases and corresponds to one of the two sort of voids mentioned above. On the other hand, experimental analysis was carried on with PMMA specimens of the same size. The first two natural frequencies of 40 cases were obtained with one void. The other three frequencies were obtained numerically. 20 of these bars were plain and the others have a notch. These experimental results were introduced in the synthetic data base. 400 cases were taken randomly and, with this information, the ANN was trained with the backpropagation algorithm. The accuracy of the results was tested with the 100 cases that were left. In the next stage of this work, the ANN output was optimized with ANFIS. Previous papers showed that localization and classification of defects was reduced as notches were introduced in such bars. In the case of this paper, improved results were obtained when a hybrid data base was used.
“…Artificial neural network has been known to provide greater scope for non-linear generalisation and ability to deal with a large number of input variables than direct application of optimisation methods [3], [4], [5]. Very little has however been reported in the literature on the use of artificial neural network method on problems related to random fatigue loading problems.…”
Random vibration fatigue loading occurs in automotive, aerospace, offshore and indeed in many structural and machine components. The analysis of these types of problems is often carried out using either time domain or frequency domain methods. Time domain rainflow counting together with Miner's linear damage accumulation assumption is widely accepted as a method of rationalising stress amplitude and mean stress from random fatigue loading and the damage caused to the component. Frequency domain methods provide a faster alternative for the analysis of the same problem but the results are generally conservative compared to those obtained using time domain methods. This paper presents an artificial neural network (ANN) machine learning approach for the prediction of damage caused by random fatigue loading. The results obtained for ergodic Gaussian stationary stochastic loading is very encouraging. The method embodies rapid analysis as well as better agreement with rainflow counting method than existing frequency domain methods.
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