Delamination of thin layers promoted by local buckling

Abstract

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 midspan, through-the-width delaminations, is taken into consideration: 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 composite materials with focus on buckling-driven delamination and four-point bending tests. Chapter 3 illustrates the experimental 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 illustrated. 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 experimental evidence. In Chapter 7, results are summarized and future developments are outlined

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