Authors: Franziska Ritschel Yang Zhou Andreas J Brunner Thomas Fillbrandt Peter Niemz
Publish Date: 2014/03/26
Volume: 48, Issue: 3, Pages: 611-631
Abstract
Several plywood materials made from spruce wood and for comparison solid spruce wood were investigated focusing on the submacroscopic damage evolution during tensile loading of the specimens The destructive tests were simultaneously monitored by the acoustic emission AE method and strain field deformation measurement using digital image correlation DIC The bilinear interpretation of exponential defect growth identified the start of significant nonlinear behavior at 70 of ultimate strength for all plywood materials However already the preceding and more stable damage evolution at lower stress levels has indicated a variation in intensity of the source mechanisms evaluated by AE energy of the detected events Additional information on the formation of strain field concentration which correlates with discrete accumulation in AE events and increased spreading in the distribution of AE energy reveals the complexity of predamage due to the variation in cracks’ magnitude and timescales involved The correlation between ultimate tensile strength and damage accumulation below 70 of ultimate strength is determined as well as the influence of layered structures on damage size shown by the percentage distribution of AE energy
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