A novel printing channel design for multi-material extrusion additive manufacturing

Additive manufacturing has a great potential in terms of its capability to produce components with complex geometries and to make multi-material and composite products by combining different materials in a single manufacturing platform. Current trends for the multi-material extrusion additive manufacturing process are categorized by multi-nozzle systems and multi-material inlet systems. In the case of multiple nozzle system, materials are deposited from different nozzles in sequence. On the other hand, in the case of multi-material inlet system, different materials are sent into a mixing tube and deposited as a mixture of materials. In this case, functionally graded parts can be fabricated by changing the volume fraction of two or more materials. Hence, the fabrication of parts with a continuous material supply by varying ratios for the extrusion technologies requires the development of printing heads with suitable printing channels, capable of varying the mixing ratio of different materials. To evaluate the effect of different printing channel designs on the material’s flow pattern and the functionally graded material printability, this paper presents a three-dimensional transient computational fluid dynamics (CFD) simulation of the two miscible liquid-liquid system in a printing channel. Different geometries and materials are considere

Unmanned aerial vehicles (UAV) for safety in the construction industry: a systematic literature review

The construction industry is one of the most dangerous sectors with poor safety performance. With recent technological developments, Unmanned Aerial Vehicles (UAV) are demonstrating the potential to be a valuable innovation to improve construction safety. To date, several studies have been conducted to evaluate the applications of UAV for safety in the construction industry. In order to systematically assess the research status on UAV to improve construction safety, this research investigated published journal articles (in English) within the Scopus database to determine the current research gaps and future work suggested by the publications. Thirty-three articles and reviews were included in the study. The analysis revealed a positive trend in publications in this area. Publications were also analysed based on the country of origin of the research and the journal. Prototype and experiments were identified as the most frequently used research methods. The majority of the studies, irrespective of the type of construction, focused on the construction stage. Where health and safety aspects were concerned, the use of UAV for visualisation and identification of hazards were found to be the most frequent applications. Some research gaps and recommendations for future research are also discussed in the pape