Volume 8, Issue 5 (May 2011)
Size Effect Related to Composite Toughness Characterization
This paper deals with toughness characterization of composite materials. In that case, Linearly Elastic Fracture Mechanics (LEFM) may not be effective because a damage zone develops at the notch tip during crack propagation. Experimental tests were carried out on two different series of homothetic specimens (Single Edge Notched Tensile and Steel Frame Assisted Tension). Data gathered for the tested sample sizes confirmed that LEFM cannot be used for toughness characterization. A macroscopic failure criterion was hence derived from experimental data. Acoustic emission data indicated fiber bridging as the main mechanism opposing crack propagation. The corresponding microscopic failure criterion is chosen to define a test-independent criterion. Cumulative statistical distributions of test-independent failure parameters were finally determined on the basis of all experimental results.