Publication details
Abstracts and keywords
The dissertation presented herein is a discussion on the application of various numerical techniques to simulate the initiation and propagation of delamination in laminated composites. Numerical analyses were performed with the use of the finite element method (FEM) utilizing the Abaqus/CAE finite element software environment, ver. 2020. The simulations were performed under a mode I loading scheme - Double Cantilever Beam (DCB). Various laminate layer layouts were utilized, with the emphasis on those featuring elastic couplings. These included bending-extension (BE) and bending-twisting (BT) couplings. For the purpose of comparing numerical modeling techniques, simulations were conducted for three techniques: Virtual Crack Closure Technique (VCCT), Surface-Based Cohesive Zone Modeling and Element-Based Cohesive Zone Modeling (CZM). The results obtained were then compared with the outcomes that had been obtained with experimental studies. Chapter 1 presents the aim and the scope of the dissertation. Chapter 2 introduces the background on composites, their classifications, the types of materials used to manufacture composites and the manufacturing methodology. The next chapter discusses the strength and stiffness parameters of polymer composites reinforced with long fibers. The methods of establishing the basic parameters of these materials are presented and the effect of elastic couplings is discussed. Chapter 4 covers the types of damage in composites and the methods of detecting them, it also discusses the basic types of standardized tests for delamination resistance in different modes. This is then followed by an analytical approach for determining the strain energy release rate (SERR) without measuring the crack length. Chapter 6 presents the numerical modeling approaches described above in detail. It also introduces and extensively discusses the results of numerical simulations. Chapter 7 compares the experimental results with the results of the numerical analyses. Then, Chapter 8 summarizes the dissertation and draws conclusions from the research. The last chapter comprises the literature reviewed in the process of creating the dissertation.
