Results and DiscussionThe crack extension calculated by an artificial neural network (ANN), using the measured acoustic emission strain wave data, was compared with the actual measured crack extension for both training and testing datasets. The abilities of the ANN were assessed http://www.selleckchem.com/products/MLN-2238.html using an RMS error in comparison to the actual and values predicted by the ANNs. The concept of plastic zone interference on the release of strain waves in the material was examined as well, leading to possible future research. The neural networks created for this research were capable of detecting the actual crack extension of the test set.3.1. Magnitude of Crack Extension3.1.1. Training Datasets The MTS machine was configured to increase the tensile load necessary to produce a displacement in the test section at a rate of 0.

01in./min. The instrumentation of the MTS machine tracked the loading force applied to the test specimen, as well as the applied displacement of one end of the specimen with respect to the other as a function of time. At a specific applied load the crack increased in size as evidenced by a sudden drop in the force applied and a corresponding sudden increase in the number of strain waves detected by the acoustic emission system. In addition any crack extension greater than 0.05in. was audible to the observers of the experiment. As soon as these phenomena were detected, the MTS machine was manually turned off, so that the displacement did not increase further and the applied load went to zero. The crack length was measured, using a digital calipers, and the displacement of the load heads was reset to the original position.

This process allowed for acoustic emission detections for a series of finite increments of crack growth, which could then be used for a training set for an artificial neural network to identify a crack extension event.The data contained in Figure 9 illustrate the results for one of the experiments using the method described above. For this case, crack growth began around 396sec after the initiation of the applied load. Sudden decreases in load indicate instances of crack extension. As shown in Figure 9(b), a plot zoomed into the crack growth time period; there were five different instances where increments of crack growth occurred (390sec, 393sec, 395.2sec, 397sec, and 398sec).

An accurate measurement of crack length growth was only possible to be taken before and after applying load to the panel. The percentage of the total crack growth at each instance was estimated, such that the cumulative crack growth equaled the measured change of the crack length.Figure 9Example of test results for panel load to onset of Carfilzomib crack extension. Each point on the plot is a single strain wave detected by either sensor 1 or 2. Although some measurements appear simultaneous in recording, there are microseconds between recordings. …