Delamination of thin layers promoted by local buckling

This dissertation investigates the combined phenomena of buckling and fracture, which occur in thin superficial layers subjected to compressive forces. As a representative case, the four-point bending test on laminated specimens with mid- span, through-the-width delaminations, is taken into consid- eration: a mechanical model of the test was developed and experimental tests on carbon fiber laminates were conducted. The thesis is subdivided into six Chapters. Chapter 1 presents a general introduction to the investigated problem. Chapter 2 illustrates the state of the art on delamination in compos- ite materials with focus on buckling-driven delamination and four-point bending tests. Chapter 3 illustrates the experimen- tal Mode II fracture toughness characterization of the carbon fiber laminates investigated in the thesis. In Chapter 4, the experimental campaign with four-point bending tests is illus- trated. Chapter 5 presents the analytical model to simulate and interpret the four-point bending tests. Chapter 6 shows a comparison between the analytical prediction and the exper- imental evidence. In Chapter 7, results are summarized and future developments are outlined.