Low Velocity Impact Response of a Novel Class of Fiber Metal Laminates Consisting of a 3D Fiberglass Fabrics

Abstract

The most important concern in automobiles collision is their crashworthiness. From an engineering point of view, the term “crashworthiness” provides a metric of the abilities of a vehicle and its components to prevent the extent of injury to vehicle’s occupants during a crash event. The Canadian motor vehicle collision statistics reported by Transport Canada reveal the importance of crashworthiness. For instance, in 2012, Canada witnessed over 2,077 deaths, 10,656 serious injuries and 152,439 minor injuries resulted from automobile collisions. The above facts and the recent challenge posed to the automotive industry to lower green-house gas emission of vehicles have sparked renewed activities in synthesizing lighter-weight materials to form various components of vehicles. However, there are basic requirements for rendering a material acceptable for use in manufacturing automobiles’ shells and enhancing their crashworthiness. Materials must have the sufficient strength, and preferably have controllable deformations under a suddenly applied load. Over the last six decades, a great volume of mass-produced vehicle panels has been manufactured mainly by metallic alloys (with steel constituting the majority of them), and in recent years, with some fiber-reinforced plastic composites (FRP). It is however believed that one can take advantage of the synergistic marriage of both metals and FRP, and develop lighter-weight and more resilient materials for use in fabrication of various components of a vehicle. The main aim of the research carried out and presented in this dissertation has therefore been to develop an innovative and effective hybrid material configuration for production of vehicle panels, with the main goals of providing comparatively optimal crashworthiness, as well as reduced weight and cost. The proposed hybrid material, referred to as 3D fiber metal laminates (3DFML), is comprised of light-weight magnesium alloy sheets and a truly 3D fiberglass fabric with its cavities filed with a foam. In this thesis, the behavior of various configurations of the developed 3DFML is systematically examined under both static and impact loading conditions. The low-velocity impact (LVI) response and failure modes of the 3DFMLs are investigated, and their performance is compared with that of conventional FML. Furthermore, computational simulations and experimental investigations are conducted to evaluate the influence of the stacking sequence on the low-velocity impact response of various configurations of 3DFML. The most optimal configuration is established based on the strength, weight and cost criteria. The level of enhancement that could be attained by using different fabric types (i.e., fiberglass and carbon) to reinforce 3DFML was also established. Furthermore, a numerical model is developed, using a commercial software (ABAQUS/Explicit), for predicting the analysis of impact response of the FMLs and assessment of their failure modes. Attempts are made to improve the interface strength by inclusion of inexpensive graphene nanoplatelets (GNP) in the interface resin. A mechanistic model is developed for estimating the strength of 3DFGFs subjected to out-of-plane compressive loading. The contribution of each constituents of fabric in carrying the load is investigated. Finally, a general practical analytical model is presented by which the impact capacity of 3DFMLs can be predicted. The developed analytical model is modified and generalized based on various configurations of the 3DFML, as well as impactor’s geometry.