Prediction models for fatigue in engineering applications are developed within a fatigue analysis framework, deliberately selected in some cases, but mostly chosen without substantiation. The proposition of this paper is that selecting the most appropriate framework can only be done with the knowledge and a complete overview of existing frameworks and their systematic categorization. In particular for composite materials, where due to coexistence of different mechanisms and their complex interaction under fatigue loading, only a unified approach can characterize the complete fatigue phenomenon. To that aid, this paper provides a complete overview of existing fatigue analysis frameworks for various materials along with such systematic categorization. Each analysis framework is based on a specific methodology that evolved over time. Hence, this overview is provided following the time stamp evolution of each methodology within different analysis frameworks. With such an overview, one can conclude that for fatigue analysis of composite materials, the theory of the thermodynamics of the irreversible processes and continuum damage mechanics framework provides the required unified approach. Additionally, this paper demonstrates that many material classes, like metals and composites, can be analysed using a common framework. This common framework has similarity up to a certain level, and at the detailed level, it differs by addressing the difference in material class-specific mechanisms. ... Read more

The process-induced voids during resistance welding of glass fabric-reinforced polyetherimide was investigated. The mechanisms of void formation in adherends, in particular, the residual volatile-induced voids and the fibre de-compaction-induced voids, were analysed. Due to the non-uniform temperature and stress distributions in the joints during welding, a non-uniform void distribution was observed in the joints with more voids generated in the middle of the joints than at the edges. Welding temperature and pressure were shown to have a large influence on void formation. Increasing of welding pressure was shown to effectively reduce the voids, while the residual moisture-induced voids were found more difficult to be eliminated than the fibre de-compaction-induced voids ... Read more

Piezoelectric materials possess nonlinear behavior when actuated in a large electric field and show a large deflection when embedded inside a composite laminate such as a LIghtweight Piezoelectric Composite Actuator. Linear and nonlinear COMSOL multi-physics finite element models were developed and validated using the actuation response of three different layups of LIghtweight Piezoelectric Composite Actuators under a cantilever beam configuration. The linear model incorporated the linear piezoelectric coefficient given from the manufacturer, while the nonlinear model incorporated the nonlinear piezoelectric coefficient plus permanent strain offset in the piezoelectric material as a result of a high applied electric field. The linear model significantly underestimated the experimental values of the actuator response and it showed that taking nonlinearity and permanent strain offset into account is an essential practice when an actuator is operated in high electric fields and accurate prediction is required. ... Read more

A 1‐D through‐the‐thickness transient heat transfer model is built to simulate the curing process of thick‐walled glass‐fibre‐reinforced anionic polyamide‐6 (APA‐6) composites. The temperature and the degree of polymerisation through the thickness of the composite are calculated and compared to the experimentally obtained results. The kinetic models describing the polymerisation behaviour of APA‐6 are implemented in the model. The kinetic model not taking into account the convection in the polymerisation process shows the best results. It is found that the predicted temperature profiles agree well with the experimental data. ... Read more

Semi-adiabatic temperature measurements are recorded and used to define semi-empirical equations for the simulation and prediction of the anionic polyamide-6 (APA-6) reaction kinetics. The resin mixture used has a long infusion window before the reaction starts. The prediction of the induction time and its corresponding initial temperature of reaction is explored. By means of this semi-empirical approach and an optimised fitting procedure, the reaction kinetics of APA-6 can successfully be described. The adiabatic polymerisation can be predicted on the basis of an autocatalytic Kamal-Sourour model for thermoset resins, and the crystallisation can be described using the isothermal crystallisation model. ... Read more