Three-dimensional printing technologies are transforming various sectors with promising technological abilities and economic outcomes. For instance, 3D-printed concrete (3DPC) is revolutionizing the construction sector with a promise to cut projects’ costs and time. Therefore, 3DPC has been subjected to extensive research and development to optimize the mechanical and thermal performance of concrete walls produced by 3D printing. In this paper, we conduct a comparative investigation of the thermal performance of various infill structures of 3DPC walls. The targeted outcome is to produce an infill structure with optimized thermal performance to reduce building energy consumption without incurring additional material costs. Accordingly, a computational model is developed to simulate the thermal behavior of various infill structures that can be used for 3DPC walls. The concrete composition and the concrete-to-void fraction are maintained constant to focus on the impact of the infill structure (geometric variations). The thermal performance and energy-saving potential of the 3DPC walls are compared with conventional construction materials, including clay and concrete bricks. The results show that changing the infill structure of the 3DPC walls influences the walls’ thermal conductivity and, thereby, the building’s thermal performance. The thermal conductivity of the examined infill structures is found to vary between 0.122 to 0.17 W/m.K, while if these structures are successful in replacing conventional building materials, the minimum annual saving in energy cost will be about $1/m². Therefore, selecting an infill structure can be essential for reducing building energy consumption.

Needle-punching is used as an alternative to expensive and sophisticated three-dimensional (3D) weaving processes to prepare a 3D composite. In this study, a 3D needled carbon–carbon (C/C) composite structure was examined using X-ray tomography and scanning electron microscopy (SEM). The effects of manufacturing porosities, needling diameter and needling density on the thermal conductivity of the composite were determined through multiscale finite-element modelling. The degradation of thermal conductivity caused by the manufacturing porosity was higher in the longitudinal direction than in the through-thickness direction. Moreover, it was found that the through-thickness thermal conductivity of the composites increased with increasing needling diameter and density.

The three-dimensional (3D) printing of polymer matrix composites has attracted considerable attention. However, the addition of filler materials to the extruded polymer matrix results in inner voids within the beads along with larger voids, called intervoids, which are generated between the beads during the 3D printing process. These voids degrade the thermal transport properties of 3D-printed polyether ether ketone (PEEK) and PEEK/carbon-fiber composites. The effects of these pores (i.e., their number, size, and location) on the thermal conductivity of 3D-printed PEEK and a PEEK/carbon-fiber composite were investigated using a multiscale finite element approach. The presence of the carbon fibers mitigated the effect of the pores on the thermal conductivity of the PEEK/carbon-fiber composite, particularly along the longitudinal direction. Moreover, the inner voids had a dominant effect on the PEEK and PEEK/carbon-fiber composite. Finally, the orientation of the intervoids had no effect on the thermal conductivity of the printed materials.

The efficient dissipation of heat has emerged as a crucial concern for modern electronic devices, given the continuous increase in their power density and consumption. Thus, the utilization of thermally conductive but electrically insulating silicone rubber composites as a thermal interface material has garnered significant interest. In this study, the effects of the filler volume fraction, filler orientation, layer volume fractions, layer configuration, and a number of layers on the thermal conductivity and electrical resistivity of silicone rubber composites were examined using a multiscale finite element modeling strategy. The results demonstrated that modification of the filler orientation can change the thermal conductivity by 28 and 21 times in the in-plane and through-thickness directions, respectively. The in-plane thermal conductivities of silicone rubber/boron nitride and silicone rubber/expanded graphite layers exhibit a percolation phenomenon at filler volume fractions of 35% and 30%, respectively. The electrical resistivity of the composite increases exponentially with a decrease in the number of layers.

Residential electricity prices in Saudi Arabia sharply increased by more than 250% in early 2018. In this study, to improve the thermal insulation efficiency of non-insulated houses, the respective effects of internal and external insulation on heat transfer through different types of brick walls with reinforced concrete floor slab were predicted by implementing a multi-scale finite-element modelling method. The results demonstrated that the efficiency of external insulation is 50% higher than that of internal insulation, and insulating a concrete brick wall is more economical than insulating a red clay brick wall. Furthermore, although external insulation saves approximately 16% more energy per year than internal insulation, the time required for the amount of energy saved to offset the cost of installation is longer.

It has long been known that residual stresses can profoundly affect the integrity of engineering components. Evidence has recently emerged to confirm that solid-state phase transformations in steels can significantly influence the as-welded residual stresses. A two-dimensional thermo-mechanical, generalized plane strain finite element model was created to simulate the effect of phase transformation on residual stress during the multi-pass weld process in a thick section T-joint. The effect of phase transformation and martensite start temperatures was investigated. The results showed that phase transformation generated compressive residual stress underneath the last bead to be deposited for this multi-pass weld model. However, some constraints around the bead were essential to provide that stress. Tensile residual stress was generated in the bulk of the weld area when phase transformation was considered. Therefore, phase transformation may be helpful for single pass and other groove welds but may be unhelpful in the case of the T-joint examined here. The effect of the martensite start temperature is small compared with the main difference between having a phase transformation and not having one.