The concept of damage tolerance is a key aspect in ensuring and maintaining safety of an airframe structure over its design life. Developments in materials and structural design have both contributed to improvements in the damage tolerance of modern aircraft structures. Indeed, new developments in metal alloys, composite materials, and hybrid materials such as the Fibre Metal Laminates (FMLs) have all resulted in structures less sensitive to damage and capable to withstand more severe loading conditions. Among other materials, FMLs represent a clear example of damage tolerant hybrid materials, made by bonding thin metal sheets together with fibres embedded in epoxy. Exploiting the damage tolerance capability of FMLs is strictly related to the ability to firstly understand the occurring failure mechanisms, and secondly to be able to accurately describe those mechanisms. In this light, the present dissertation describes the investigation on the residual strength failure sequence in FMLs, and presents the development of an accurate analytical prediction method. The failure sequence is studied in particular for standard Glare laminates, which are relevant laminates for applications in aircraft pressurized fuselages. The developed analytical method has been implemented into two numerical models, considering both through-the-thickness crack and fatigue crack configurations. The developed models are validated against a large number of experimental data, which are also presented in this thesis. The main concept in this dissertation is that the crack growth process in the metallic layers of an FML can be described with the Crack Tip Opening Angle concept (CTOA). This approach includes the contribution of the fibre layers (e.g. fibre failure and fibre bridging) and the associated quasi-static delamination growth. An introduction to FMLs and to all various Glare grades, lay-ups, and manufacturing processes is provided in chapter 2. Some current and future applications for aircraft structures are also discussed in that chapter. A qualitative description of the principal failure mechanisms occurring during the residual strength failure sequence is presented in chapter 3. Based on experimental observations, the metal crack growth mechanisms, permanent plastic deformation, fibre failure and static delamination growth are discussed. All these mechanisms are related to each other, and all contribute to the residual strength of the laminate. The development of the prediction models aimed to be a step forward with respect to previous relevant prediction models available in literature. Therefore, both empirical and analytical prediction models available in literature are presented and discussed in chapter 4. A critical evaluation of those models has pointed out their limitations in applicability and versatility towards a “generic FML” concept. From this chapter, some guidelines have been defined to address the subsequent model development. Two types of experimental activities were carried out. The first type consisted in experiments to gain understanding of the deformation behaviour of both metallic and fibre layers. Extensive use of Digital Image Correlation technique enabled to observe and measure the deformation field of both metal and fibre layers, and their interaction. Further insight into the fibre bridging mechanism and into the metal-fibre interaction was obtained. These experimental activities are discussed in chapter 5. The second type of experimental activities aimed to generate input data for the prediction model, and to validate the CTOA approach. These are discussed in chapter 6. A large amount of experimental CTOA tests were conducted on several FML grades to evaluate the CTOA as failure criterion for FML. This included the investigation of the effect of metal sheet thickness, crack length-to-panel width ratio and the effect of bridging fibres. Static delamination growth tests were conducted to obtain the critical Strain Energy Release Rate. This parameter was subsequently used as input in the prediction model to define the critical condition for the delamination growth. Furthermore, in the same chapter, it is also discussed the complex interaction between static delamination growth and plastic deformation of the metallic layers. The core aspect of the present thesis concerns the modelling of the residual strength failure sequence, which is presented in chapter 7. Two models are described: one for the through-the-thickness crack and one for the fatigue crack. Both models are based on the same method, which uses the CTOA as crack growth driving parameter. The method is based on the idea that crack extension in the metallic layers occurs when the calculated CTOA reaches the critical value obtained from CTOA experiments on metal laminates containing the same metal layers used in the FML. The calculated CTOA is a function of the contribution due to the far-field stress in the aluminium layers, and the contribution of the fibres. The fibre can contribute either in terms of crack opening contribution (broken fibres) or crack closing contribution (bridging fibres present in the fatigue crack configuration). Plastic deformation ahead and behind the metal crack tip is accounted and implemented into the calculation. In addition, in the case of fatigue crack configurations, the bridging stress is calculated by solving the deformation compatibility equation, accounting for the plastic zone ahead of the crack tip and fibre failure in the bridging area. The bridging stress is subsequently used to calculate the quasi-static delamination growth occurring at the fibre-metal interface using the Strain Energy Release Rate approach. The model for through-the-thickness crack showed a very good agreement with the experimental data, while the model for fatigue crack configuration showed sufficient agreement with experimental data. The modelling of the fatigue crack configuration presents higher degree of complexity, which required a number of simplifications and assumptions, making the model less robust than the one for through-the-thickness crack. Chapter 8 summarises the conclusions of the investigations. It can be concluded that with the proposed models, the mechanisms related to the residual strength failure sequence are fully described and characterized. The model for through-the-thickness crack is robust and validated, and can be extended to other material and geometrical configurations. The model for fatigue crack is not robust enough, but further improvements are possible.