Failure of marine composite materials due to blast loading
An experimental investigation in to the dynamic response and blast resistance of composite materials and several other composite based structural materials has been conducted. The effect of layering, sandwich construction and design modifications of the components of a sandwich has been studied. Finally, the individual role of components of a sandwich to blast loading and combined role of these components as a sandwich has also been investigated. ^ The manuscript of the dissertation comprises of five chapters. The first chapter provides an introduction to the previous research done on composite materials and structures under dynamic loading conditions, such as those existing in blast loadings. Subsequent chapters look into a certain aspect of the given composite structural behavior under blast loading conditions. ^ Chapter two deals with fiber based composites. In this study, two different fiber materials, namely, E-Glass and Carbon, with different architecture are chosen. Polymer (Vinyl Ester) based composites were designed using these fibers and were fabricated using VARTM process. These composites were subjected to quasi-static and high strain rates of loading utilizing different testing methodologies. In quasi-static testing, the tensile, compressive and shear properties were studied using existing ASTM standard testing procedures and the results are reported. The carbon composite showed higher tensile and compressive modulus. In plane shear properties of both the composites were comparable and inter laminar shear properties of E-Glass composites were observed to be better than the carbon composite because of the better nesting between the E-Glass fabric layers. A shock tube and a controlled explosion tube were utilized in the study of dynamic damage behavior of these composite materials. Based on the experimental study, it is observed that the carbon fiber composites tend to achieve sudden destructive damage whereas E-Glass fiber composites tend to sustain progressive damage, under dynamic loading. ^ The third chapter deals with layered composite materials. In this work, layered and sandwich composite materials, comprising of polyurea (PU) and E-glass vinyl ester (EVE) composite are experimentally evaluated for effective blast resistance using a shock tube. Results indicate that addition of the polyurea layer on the impact face considerably increases the blast resistance. Further, sandwich materials prepared by sandwiching the polyurea between two composite skins had the best blast resistance compared to the layered and the composite plates. ^ The fourth chapter deals with sandwich composite materials. The present study utilizes 3-D woven composites skins and transversely reinforced core for strengthening of the sandwich. The effect of these modifications on the transient response of such sandwich composites is experimentally studied. The experimental program is focused on recording dynamic transient response by high-speed camera and post-mortem evaluation of imparted damage. The obtained experimental results reveal important features of the transient deformation, damage initiation and progression and final failure modes in sandwich composites with unstitched and stitched foam cores. ^ The final chapter deals with understanding of the contribution of individual elements of a sandwich composite material. A carbon fiber vinyl ester skin material, and balsa core material, was studied under controlled blast loading conditions. The real time deflection, combined with the damage behavior provided an understanding into the blast resistance of these components and thus could facilitate better design and construction principles for sandwich composite materials. (Abstract shortened by UMI.)^
Applied Mechanics|Engineering, Mechanical
Srinivasan Arjun Tekalur,
"Failure of marine composite materials due to blast loading"
Dissertations and Master's Theses (Campus Access).