Geometric Modeling of Cellular Materials for Additive Manufacturing in Biomedical Field: A Review

Advances in additive manufacturing technologies facilitate the fabrication of cellular materials that have tailored functional characteristics. The application of solid freeform fabrication techniques is especially exploited in designing scaffolds for tissue engineering. In this review, firstly, a classification of cellular materials from a geometric point of view is proposed; then, the main approaches on geometric modeling of cellular materials are discussed. Finally, an investigation on porous scaffolds fabricated by additive manufacturing technologies is pointed out. Perspectives in geometric modeling of scaffolds for tissue engineering are also proposed

The Evolution of 3D Printing in AEC: From Experimental to Consolidated Techniques

The chapter leads the reader through the historical development of additive manufacturing (AM) techniques until the most recent developments. A tentative taxonomy is added to the historical perspective, in order to better understand the main lines of development and the potential cross-fertilization opportunities. Some case studies are analyzed in order to provide a clearer picture of the practical applications of AM in architecture engineering and construction (AEC), with a particular attention to the use of AM for final products rather than just prototypes. Eventually, some thoughts are shared as to the impact of AM on AEC beyond the mere cost-effectiveness and well into the potential change of paradigms in how architecture can be thought of and further developed embracing the new world of opportunities brought by AM

Proceedings of the 2021 DigitalFUTURES

This open access book is a compilation of selected papers from 2021 DigitalFUTURES—The 3rd International Conference on Computational Design and Robotic Fabrication (CDRF 2021). The work focuses on novel techniques for computational design and robotic fabrication. The contents make valuable contributions to academic researchers, designers, and engineers in the industry. As well, readers encounter new ideas about understanding material intelligence in architecture

Development of innovative cross-disciplinary engineering showcase

The development of engineering education relies substantially on interactive showcases and practical knowledge. The cross-disciplinary engineering showcase is designed to be fully interactive by having user input, producing a tangible output, and to understand distinct elements from each of the engineering disciplines such as, civil, mechanical and electrical (CME). The showcase operates from the input of mechanical rotational energy by the user pedalling the exercycle. Mechanical energy is then transferred to the pump via a gear train, which converts the user input of 30 rpm to the optimal pump operating speed of 2900 rpm. Further, it is used to pump water from the lower eservoir to the upper reservoir via one of the three flow paths, which the user can select by opening or closing flow valves. Once the water reaches a given height, it then flows back to the lower reservoir via a micro-hydro generator. As a result, it generates electrical energy stored in a power bank that can be used by the user to charge a digital device. Also, the showcase has a QR code to digital media, which will provide an additional explanation/exposition of the presented engineering principles to the user/students. The aim of this project is to develop a cross- disciplinary engineering showcase to enhance student learnings by interpreting the CME engineering principles in schools, institutes, and universities

Surface engineering by titanium particulate injection mounding

In a recent study a structural hold down component was designed and produced using the particulate injection moulding (PIM) process. The material of choice was titanium due not only to the material properties but also due to the desire to create custom made components for a state-of-the-art marine vessel. On removal from the mould the green parts were seen to have an irregular surface on the top face. The irregular surface presented no through part defects and although the surface irregularities were caused by separation of the two-phases the effect was restricted to the outer surface of the parts. In a more historic study by the author the surface properties of titanium dental implants were modified by the use of adaptive mould inserts during the moulding phase of PIM. These two contrasting studies are considered and have become the basis of a current investigation looking to engineer surface irregularities in an ordered fashion. The application of meso-machining, and additive manufacture are considered and the functionality which may arise are presented

Development of innovative cross-disciplinary engineering showcase

The development of engineering education relies substantially on interactive showcases and practical knowledge. The cross-disciplinary engineering showcase is designed to be fully interactive by having user input, producing a tangible output, and to understand distinct elements from each of the engineering disciplines such as, civil, mechanical and electrical (CME). The showcase operates from the input of mechanical rotational energy by the user pedalling the exercycle. Mechanical energy is then transferred to the pump via a gear train, which converts the user input of 30 rpm to the optimal pump operating speed of 2900 rpm. Further, it is used to pump water from the lower eservoir to the upper reservoir via one of the three flow paths, which the user can select by opening or closing flow valves. Once the water reaches a given height, it then flows back to the lower reservoir via a micro-hydro generator. As a result, it generates electrical energy stored in a power bank that can be used by the user to charge a digital device. Also, the showcase has a QR code to digital media, which will provide an additional explanation/exposition of the presented engineering principles to the user/students. The aim of this project is to develop a cross- disciplinary engineering showcase to enhance student learnings by interpreting the CME engineering principles in schools, institutes, and universities

A new resonance-based design approach to reduce motor torque requirements in automated machinery

In the last decades, compliant mechanisms have been widely studied but their application has not been widespread due to their susceptibility to fatigue and the lack of systematic design methodologies. In this paper, the authors propose a new approach to be used in the automated machinery mechanism design (the mechanisms are usually subjected to predominant inertial loads) that exploits the capability of the compliant joints to store and release elastic energy in order to reduce the motor torque requirements. Thanks to the carbon-fiber reinforced 3D printing technologies, the compliant joint stiffness can be properly designed to obtain, for the considered mechanism, a resonant condition during its nominal functioning. Moreover, topology optimization can be successfully employed to reduce the mechanism component inertia (keeping the same overall mechanism stiffness) and thus, further diminish the torque requirements. In order to assess the quality of the proposed approach, a pusher mechanism used in a real automated machine has been considered. A prototype has been manufactured to evaluate the effect of the compliant joint introduction and the topology optimization on the motor torque reduction. To validate the results, an experimental campaign has been conducted. Comparison between the standard design approach and the new one emphasizes the superior contribution of compliant joint introduction on the motor torque reduction: a 97% and 96% reduction on the RMS and peak motor torque, respectively, is achieved resorting to the new design approach. Although a high repeatability is achieved, a slight deviation of the trajectory with respect to the ideal one is however registered

Strategies towards large-scale 3D printing without size constraints

Three-dimensional (3D) printing has been profoundly changing the production mode of traditional industries. However, this technique is usually limited to metre-scale fabrication, which prevents large-scale 3D printing (LS3DP) applications such as the manufacturing of buildings, aircraft, ships, and rockets. LS3DP faces great challenges, particularly, it not only requires confronting problems not yet solved by conventional 3D printing, such as the inability to print functional structures due to limitations by single-material manufacturing, but also needs to overcome the size effect limitation of large-scale printing. Here, we systematically review the state of the art in the integration of materials and technologies in LS3DP. We also demonstrate some disruptive engineering cases of LS3DP in the field of construction. The challenges and strategies for overcoming size constraints to achieve LS3DP of functional structures are discussed, including multifunctional 3D printing processes from nano- to large-scale and large-scale 4D printing processes, diverse printable materials and sustainable structures, horizontal and vertical size-independent printers, collaborative and intelligent control of the entire process, and extreme environment printing. These strategies can provide tremendous opportunities for the fully automated, intelligent, and unmanned production of these different material megastructures and internal multiscale multifunctional components such as buildings/structures, aerospace vehicles, and marine equipment

Experimental investigation and statistical analysis of additively manufactured onyx-carbon fiber reinforced composites

This is the peer reviewed version of the following article published in final form at https://doi.org/10.1002/app.50338. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Availability of additive manufacturing (AM) has influenced the scientific community to improve on production and versatility of the components created with several associated technologies. Adding multiple substances through superimposing levels is considered as a part of three-dimensional (3D) printing innovations to produce required products. These technologies are experiencing an increase in development nowadays. It requires frequently adding substance and has capacity to fabricate extremely complex geometrical shapes. However, the fundamental issues with this advancement include alteration of capacity to create special products with usefulness and properties at an economically viable price. In this study, significant procedural parameters: layer designs/ patterns (hexagonal, rectangular and triangular) and infill densities (30, 40 and 50%) were considered to investigate into their effects on mechanical behaviors of fused deposition modeling (FDM) or 3D-printed onyx-carbon fiber reinforced composite specimens, using a high-end 3D printing machine. Mechanical (tensile and impact) properties of the printed specimens were conclusively analyzed. From the results obtained, it was observed that better qualities were achieved with an increased infill density, and rectangular-shaped design exhibited an optimum or maximum tensile strength and energy absorption rate, when compared with other counterparts. The measurable relapse conditions were viably evolved to anticipate the real mechanical qualities with an accuracy of 96.4%. In comparison with other patterns, this was more closely predicted in the rectangular design, using regression models. The modeled linear regression helps to define the association of two dependent variables linked with properties of the dissimilar composite material natures. The models can further predict response of the quantities before and also guide practical applications.Peer reviewedFinal Accepted Versio