Investigation of the Staging of Damage Accumulation in Polymer Composite Materials during Bending and Tensile Tests

Abstract

The paper presents the results of the study of registered acoustic emission (AE) parameters during static deformation and damaging of polymer composite materials (PCM). Mechanical tests were done by a static tension and a static three-point bend, accompanied by an acoustic emission method. The assessment of the loading rate effect on defects formation processes was done by additional static tension test at rate equal half of recommended by the standard and static three-point bend test at rate ten times lower than that calculated by the standard. Clustering by frequency components of the recorded AE signals with a self-organizing Kohonen map was performed. The characteristics of the types of PCM structure damage by the centroids of the obtained clusters are given. Based on the clusters accumulation during mechanical tests, the stages of damage formation for static tension and static three-point bend, the loading rate effect on the process of damage formation are described.

Identification of Acoustic Emission Sources in a Polymer Composite Material under Cycle Tension Loading

“…The obtained spectra were input to a self-organizing map. The number of output clusters (equal to 100 pieces) was selected empirically based on the reproducibility of clustering results, including for other types of mechanical tests [19]. Such number of clusters makes it possible to separate AE signals from formed damages of a mixed nature in the material and noise signals separately [12].…”

Study of Thermal Aging of the PCM Using Acoustic Emission and Optical Microscopy

“…For the recorded AE signals, the Fourier spectra were calculated, the analysis range of which was limited to the frequency range of 20-450 kHz [21]. To reduce the influence of the signal amplitude, spectrum normalization performed [22].…”