The manufacturing process in thermoset-based carbon fiber-reinforced polymers (CFRPs) usually requires a curing stage where the material is transformed from a gel state to a monolithic solid state. During the curing process, micro-residual stresses are developed in the material due to the different chemical–thermal–mechanical properties of the fiber and of the polymer, reducing the mechanical performance of the composite material compared to the nominal performance. In this study, computational micromechanics is used to analyze the micro-residual stresses development and to predict its influence on the mechanical performance of a pre-impregnated unidirectional CFRP made of T700-fibers and an aeronautical grade epoxy. The numerical model of a representative volume element (RVE) was developed in the commercial software Abaqus^® and user-subroutines are used to simulate the thermo-curing process coupled with the mechanical constitutive model. Experimental characterization of the bulk resin properties and curing behavior was made to setup the models. The higher micro-residual stresses occur at the thinner fiber gaps, acting as triggers to failure propagation during mechanical loading. These micro-residual stresses achieve peak values above the yield stress of the resin 55 MPa, but without achieving damage. These micro-residual stresses reduce the transverse strength by at least 10%, while the elastic properties remain almost unaffected. The numerical results of the effective properties show a good agreement with the macro-scale experimentally measured properties at coupon level, including transverse tensile, longitudinal shear and transverse shear moduli and strengths, and minor in-plane and transverse Poisson’s ratios. A sensitivity analysis was performed on the thermal expansion coefficient, chemical shrinkage, resin elastic modulus and cure temperature. All these parameters change the micro-residual stress levels and reduce the strength properties.

One of the main advantages of carbon fiber-reinforced polymer (CFRP) electronic housings, when compared with traditionally used aluminum ones, is the potential for mass savings. In recent years, the power consumption of electronics has been growing, resulting in the need for higher thermal dissipation of electronic housings, requiring the use of highly thermally conductive materials. In this work, the manufacturing of a highly conductive CFRP electronic housing is reported. With a view to reducing total energy costs on manufacturing, an out-of-the autoclave manufacturing process was followed. Due to the inherent low thermal conductivity of typical raw materials for composite materials, strategies were evaluated to increase its value by changing the components used. The use of pitch-based carbon fibers was found to be a very promising solution. In addition, structural, thermal and manufacturing simulations were produced in the design phase. Improved performance was demonstrated from materials manufacturing to final breadboard testing. The results indicate potential gains of around 23% in mass reduction when compared to conventional aluminum electronic boxes. Moreover, the proposed design and the manufactured breadboard showed good compliance with mechanical and electrical requirements for spacecraft structures. The thermal balance results showed a performance slightly below to what would be expected from the detailed design.

As the use of composite materials increases, the search for suitable automated processes gains relevance for guaranteeing production quality by ensuring the uniformity of the process, minimizing the amount of scrap generated, and reducing the time and energy consumption. Limitations on production by traditional means such as hand lay-up, vacuum bagging, and in-autoclave methods tend not to be as efficient when the size and shape complexity of the part being produced increases, motivating the search for alternative processes such as automated tape laying (ATL). This work aims to describe the process of modelling and simulating a composite ATL with in situ consolidation by characterizing the machine elements and using the finite differences method in conjunction with energy balances in order to create a digital twin of the process for further control design. The modelling approach implemented is able to follow the process dynamics when changes are made to the heating element and to predict the composite material temperature response, making it suitable for use as a digital twin of a production process using an ATL machine.

A model to determine the performance of different configurations of single axis tracking is presented. The analysis of the results shows that the output of a PV receptor mounted on an inclined axis with a north‐south direction has a high acceptance angle and features low power losses, since the misalignments are greatest when the available irradiation is lowest. These results suggest the possibility of single axis tracking for low concentration CPV systems.