AN ALGORITHM FOR DETERMINING THE ONSET OF PLASTIC DEFORMATION BASED ON THE MICROMECHANICAL MODEL OF ACOUSTIC EMISSION
Keywords:
acoustic emission, micromechanical model of acoustic emission, optimization for calculating the criterial parameterAbstract
In this paper improved algorithm for determining the onset of plastic deformation is proposed. It is based on the application of micromechanical model of acoustic emission. The multi-parameter model considers anisotropy of mechanical properties of studied object, temperature and inhomogeneity of material. The model assigns the parameter of object's state (residual life, the start of plastic deformation) to acoustic emission parameter (the total number of AE-pulses). Object of study is polymer composite material driven to destruction with tensile load. Registration of acoustic signals during a tensile test was performed using industrial AE system «A-Line32D». Dependence of the total number of AE pulses from time was obtained based on the received data. Micromechanical model of acoustic emission was applied for assessment of the state of the object at different load levels using approximation total AE function. During approximation mathematical model’ parameters are determined, and criterial evaluation of object's state is carried out. One of the stages of research is to determine the most informative diagnostic parameter. Numerical simulation destruction of composite material with known start point of plastic deformation was carried out. Application micromechanical model of acoustic emission on the mathematical model of composite destruction allows to determine diagnostic parameter for evaluation of object's state. According to the research results the diagnostic parameter is limit of Weibull-Gnedenko distribution. This parameter characterizes less durable structural element. Unfortunately, application of micromechanical model in online mode is difficult. It is due to the requirements of large computational resources in the process of approximation of the total accounting function. For online mode improved algorithm for determining the start point of plastic deformation is proposed. The modification of the algorithm consists in using a smaller number of variables when calculating the criterial parameter. Testing of the algorithm was carried out with real AE data obtained from testing of composite materials.
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