Challenges and Status on Design and Computation for Emerging Additive Manufacturing Technologies

The revolution of additive manufacturing (AM) has led to many opportunities in fabricating complex and novel products. The increase of printable materials and the emergence of novel fabrication processes continuously expand the possibility of engineering systems in which product components are no longer limited to be single material, single scale, or single function. In fact, a paradigm shift is taking place in industry from geometry-centered usage to supporting functional demands. Consequently, engineers are expected to resolve a wide range of complex and difficult problems related to functional design. Although a higher degree of design freedom beyond geometry has been enabled by AM, there are only very few computational design approaches in this new AM-enabled domain to design objects with tailored properties and functions. The objectives of this review paper are to provide an overview of recent additive manufacturing developments and current computer-aided design methodologies that can be applied to multimaterial, multiscale, multiform, and multifunctional AM technologies. The difficulties encountered in the computational design approaches are summarized and the future development needs are emphasized. In the paper, some present applications and future trends related to additive manufacturing technologies are also discussed

Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

The 1st Advanced Manufacturing Student Conference (AMSC21) Chemnitz, Germany 15–16 July 2021

The Advanced Manufacturing Student Conference (AMSC) represents an educational format designed to foster the acquisition and application of skills related to Research Methods in Engineering Sciences. Participating students are required to write and submit a conference paper and are given the opportunity to present their findings at the conference. The AMSC provides a tremendous opportunity for participants to practice critical skills associated with scientific publication. Conference Proceedings of the conference will benefit readers by providing updates on critical topics and recent progress in the advanced manufacturing engineering and technologies and, at the same time, will aid the transfer of valuable knowledge to the next generation of academics and practitioners. *** The first AMSC Conference Proceeding (AMSC21) addressed the following topics: Advances in “classical” Manufacturing Technologies, Technology and Application of Additive Manufacturing, Digitalization of Industrial Production (Industry 4.0), Advances in the field of Cyber-Physical Systems, Virtual and Augmented Reality Technologies throughout the entire product Life Cycle, Human-machine-environment interaction and Management and life cycle assessment.:- Advances in “classical” Manufacturing Technologies - Technology and Application of Additive Manufacturing - Digitalization of Industrial Production (Industry 4.0) - Advances in the field of Cyber-Physical Systems - Virtual and Augmented Reality Technologies throughout the entire product Life Cycle - Human-machine-environment interaction - Management and life cycle assessmen

Biomanufacturing Technologies for Tissue Engineering

Il seguente lavoro di tesi ha come obiettivo lo studio e la realizzazione di device biomedicali realizzati tramite la manifattura additiva. La manifattura additiva sta avendo una forte crescita negli ultimi anni grazie soprattutto alla possibilità di realizzare facilmente geometrie complesse. Questa caratteristica permette di personalizzare i prodotti ad un costo competitivo. Inoltre, lo spreco di materiale viene ridotto moltissimo dal principio di fabbricazione. Tutte queste proprietà hanno fatto in modo che negli ultimi anni la manifattura additiva prendesse sempre più piede in campi come l’automotive, l’aerospace e il biomedicale. Questo lavoro di tesi è focalizzato sull’utilizzo di alcune tra le più diffuse tecnologie additive per la produzione di device biomedicali. In particolare, il lavoro si è concentrato principalmente sulla realizzazione di due modelli, il primo per lo studio dello sviluppo dei black floaters all’interno del corpo vitreo dell’occhio, il secondo per l’emulazione del comportamento dell’osso mandibolare durante la foratura per l’installazione di impianti dentali. Il modello dell’occhio è composto da due elementi principali, un supporto e un hydrogel. Il supporto serve a contenere e supportare l’hydrogel. Deve essere trasparente, biocompatibile facilmente manovrabile in laboratorio. La sua realizzazione è avvenuta tramite stereolitografia. L’hydrogel, invece, ha lo scopo di fornire un’ambiente 3D per la crescita e sviluppo delle cellule. Deve perciò anche lui essere biocompatibile e con adeguate caratteristiche meccaniche e di stampabilità. La struttura 3D è stata realizzata tramite material extrusion. Il modello di osso mandibolare è stato realizzato tramite fused filament fabrication. Il modello si compone di due parti, una parte esterna piena per emulare l’osso corticale, e una parte interna porosa per emulare l’osso trabecolare. Le prove di foratura sono state realizzate con un trapano dentistico agganciato a robot collaborativi. La ricerca ha infine toccato ulteriori due ambiti, lo studio delle proprietà di strutture lattice realizzate tramite laser based- powder bed fusion e la valutazione di diversi trattamenti di finitura superficiale. La tesi, dunque, ha la seguente organizzazione. Il capitolo 1 presenta un’introduzione sull’additive manufacturing e il bioprinting. Le tecnologie ed i materiali utilizzati sono brevemente descritti e sono riportati alcuni esempi di applicazione della manifattura additiva nel campo biomedicale. I capitoli seguenti, invece, riportano gli articoli pubblicati o in corso di pubblicazione riguardo alle diverse tematiche affrontate. Nello specifico, il capitolo 2 riporta la ricerca sulle strutture lattice e la loro realizzazione. I capitoli 3 e 4 comprendono gli studi relativi al modello dell’occhio. Il capitolo 3 si concentra sulla realizzazione del supporto, il 4 sulla formulazione e la valutazione dell’hydrogel. Il capitolo 5 approfondisce lo studio del modello per l’emulazione del comportamento dell’osso mandibolare a foratura mentre il capitolo 6, l’ultimo di questo elaborato, si concentra sui processi di finitura superficiale. Per concludere, la manifattura additiva include processi molto diversi tra loro, ma che presentano molti punti in comune come la flessibilità, libertà di progettazione e personalizzazione. Sfruttando queste proprietà è possibile realizzare oggetti su misura, soprattutto in campi come quello biomedicale dove la personalizzazione e la specificità sono fondamentali.The following thesis aims to study and to develop biomedical devices made through additive manufacturing. Additive manufacturing has been experiencing a strong growth in recent years, mainly due to its ability to easily realize complex geometries. This feature allows customization of products at a competitive cost. In addition, material waste is greatly reduced by the manufacturing principle. All these properties helped the recent years diffusion of additive manufacturing in fields such as automotive, aerospace and biomedical. This thesis focuses on the use of some of the most popular additive technologies for the production of biomedical devices. In particular, the work focused mainly on the fabrication of two models, the first to study the development of black floaters within the vitreous body of the eye, and the second to emulate the mandibular bone behavior during drilling for the installation of dental implants. The eye model consists of two main elements, a scaffold and a hydrogel. The scaffold contains and provides support to the hydrogel. It must be transparent, biocompatible easily handled in the laboratory. It is printed by stereolithography. The hydrogel, on the other hand, is intended to provide a 3D environment for cell growth and development. Therefore, it must be biocompatible and have adequate mechanical properties together with good printability. The 3D scaffold structure was made by material extrusion. The mandibular bone model was made by fused filament fabrication. The model consists of two parts, a solid outer part to emulate cortical bone, and a porous inner part to emulate trabecular bone. Drilling tests were performed with a dental drill attached to collaborative robots. Finally, the research covered two additional areas, the study of the properties of lattice structures made by laser-based- powder bed fusion and the evaluation of different surface finish treatments. The following thesis, therefore, has the following organization. Chapter 1 presents an introduction on additive manufacturing and bioprinting. The technologies and materials used are briefly described, and examples of additive manufacturing applications in the biomedical field are given. The following chapters, on the other hand, report published or forthcoming articles regarding the various topics mentioned above. Specifically, Chapter 2 reports the research on lattice structures and their fabrication. Chapters 3 and 4 include studies related to the eye model. Chapter 3 focuses on the fabrication of the support, and Chapter 4 on the formulation and evaluation of the hydrogel. Chapter 5 presents the study of the model for emulating the behavior of mandibular bone upon drilling, while Chapter 6, the last of this work, focuses on surface finishing processes. In conclusion, additive manufacturing includes various processes that are very different from each other but have many common points such as flexibility, freedom of design, and customization. By exploiting these properties, it is possible to make tailored objects, especially important in fields such as the biomedical one, where customization and specificity are a great added value

A comparison of processing techniques for producing prototype injection moulding inserts.

This project involves the investigation of processing techniques for producing low-cost moulding inserts used in the particulate injection moulding (PIM) process. Prototype moulds were made from both additive and subtractive processes as well as a combination of the two. The general motivation for this was to reduce the entry cost of users when considering PIM. PIM cavity inserts were first made by conventional machining from a polymer block using the pocket NC desktop mill. PIM cavity inserts were also made by fused filament deposition modelling using the Tiertime UP plus 3D printer. The injection moulding trials manifested in surface finish and part removal defects. The feedstock was a titanium metal blend which is brittle in comparison to commodity polymers. That in combination with the mesoscale features, small cross-sections and complex geometries were considered the main problems. For both processing methods, fixes were identified and made to test the theory. These consisted of a blended approach that saw a combination of both the additive and subtractive processes being used. The parts produced from the three processing methods are investigated and their respective merits and issues are discussed

Reducing risk in pre-production investigations through undergraduate engineering projects.

This poster is the culmination of final year Bachelor of Engineering Technology (B.Eng.Tech) student projects in 2017 and 2018. The B.Eng.Tech is a level seven qualification that aligns with the Sydney accord for a three-year engineering degree and hence is internationally benchmarked. The enabling mechanism of these projects is the industry connectivity that creates real-world projects and highlights the benefits of the investigation of process at the technologist level. The methodologies we use are basic and transparent, with enough depth of technical knowledge to ensure the industry partners gain from the collaboration process. The process we use minimizes the disconnect between the student and the industry supervisor while maintaining the academic freedom of the student and the commercial sensitivities of the supervisor. The general motivation for this approach is the reduction of the entry cost of the industry to enable consideration of new technologies and thereby reducing risk to core business and shareholder profits. The poster presents several images and interpretive dialogue to explain the positive and negative aspects of the student process

Unveiling the prospects of point-of-care 3D printing of Polyetheretherketone (PEEK) patient-specific implants

Additive manufacturing (AM) or three-dimensional (3D) printing is rapidly gaining acceptance in the healthcare sector. With the availability of low-cost desktop 3D printers and inexpensive materials, in-hospital or point-of-care (POC) manufacturing has gained considerable attention in personalized medicine. Material extrusion-based [Fused Filament Fabrication (FFF)] 3D printing of low-temperature thermoplastic polymer is the most commonly used 3D printing technology in hospitals due to its ease of operability and availability of low-cost machines. However, this technology has been limited to the production of anatomical biomodels, surgical guides, and prosthetic aids and has not yet been adopted into the mainstream production of patient-specific or customized implants. Polyetheretherketone (PEEK), a high-performance thermoplastic polymer, has been used mainly in reconstructive surgeries as a reliable alternative to other alloplastic materials to fabricate customized implants. With advancements in AM systems, prospects for customized 3D printed surgical implants have emerged, increasing attention for POC manufacturing. A customized implant may be manufactured within few hours using 3D printing, allowing hospitals to become manufacturers. However, manufacturing customized implants in a hospital environment is challenging due to the number of actions necessary to design and fabricate the implants. The focus of this thesis relies on material extrusion-based 3D printing of PEEK patient-specific implants (PSIs). The ambitious challenge was to bridge the performance gap between 3D printing of PEEK PSIs for reconstructive surgery and the clinical applicability at the POC by taking advantage of recent developments in AM systems. The main reached milestones of this project include: (i) assessment of the fabrication feasibility of PEEK surgical implants using material extrusion-based 3D printing technology, (ii) incorporation of a digital clinical workflow for POC manufacturing, (iii) assessment of the clinical applicability of the POC manufactured patient-specific PEEK scaphoid prosthesis, (iv) visualization and quantification of the clinical reliability of the POC manufactured patient-specific PEEK cranial implants, and (v) assessment of the clinical performance of the POC manufactured porous patient-specific PEEK orbital implants. During this research work, under the first study, we could demonstrate the prospects of FFF 3D printing technology for POC PEEK implant manufacturing. It was established that FFF 3D printing of PEEK allows the construction of complex anatomical geometries which cannot be manufactured using other technologies. With a clinical digital workflow implementation at the POC, we could further illustrate a smoother integration and faster implant production (within two hours) potential for a complex-shaped, patented PEEK patient-specific scaphoid prosthesis. Our results revealed some key challenges during the FFF printing process, exploring the applicability of POC manufactured FFF 3D printed PEEK customized implants in craniofacial reconstructions. It was demonstrated that optimal heat distribution around the cranial implants and heat management during the printing process are essential parameters that affect crystallinity, and thus the quality of the FFF 3D printed PEEK cranial implants. At this stage of the investigation, it was observed that the root mean square (RMS) values for dimensional accuracy revealed higher deviations in large-sized cranial prostheses with “horizontal lines” characteristics. Further optimization of the 3D printer, a layer-by-layer increment in the airflow temperature was done, which improved the performance of the FFF PEEK printing process for large-sized cranial implants. We then evaluated the potential clinical reliability of the POC manufactured 3D printed PEEK PSIs for cranial reconstruction by quantitative assessment of geometric, morphological, and biomechanical characteristics. It was noticed that the 3D printed customized cranial implants had high dimensional accuracy and repeatability, displaying clinically acceptable morphologic similarity concerning fit and contours continuity. However, the tested cranial implants had variable peak load values with discrete fracture patterns from a biomechanical standpoint. The implants with the highest peak load had a strong bonding with uniform PEEK fusion and interlayer connectivity, while air gaps and infill fusion lines were observed in implants with the lowest strength. The results of this preclinical study were in line with the clinical applicability of cranial implants; however, the biomechanical attribute can be further improved. It was noticed that each patient-specific reconstructive implant required a different set of manufacturing parameters. This was ascertained by manufacturing a porous PEEK patient-specific orbital implant. We evaluated the FFF 3D printed PEEK orbital mesh customized implants with a metric considering the design variants, biomechanical, and morphological parameters. We then studied the performance of the implants as a function of varying thicknesses and porous design constructs through a finite element (FE) based computational model and a decision matrix based statistical approach. The maximum stress values achieved in our results predicted the high durability of the implants. In all the implant profile configurations, the maximum deformation values were under one-tenth of a millimeter (mm) domain. The circular patterned design variant implant revealed the best performance score. The study further demonstrated that compounding multi-design computational analysis with 3D printing can be beneficial for the optimal restoration of the orbital floor. In the framework of the current thesis, the potential clinical application of material extrusion-based 3D printing for PEEK customized implants at the POC was demonstrated. We implemented clinical experience and engineering principles to generate a technical roadmap from preoperative medical imaging datasets to virtual surgical planning, computer-aided design models of various reconstructive implant variants, to the fabrication of PEEK PSIs using FFF 3D printing technology. The integration of 3D printing PEEK implants at the POC entails numerous benefits, including a collaborative team approach, quicker turnaround time of customized implants, support in pre-surgical and intraoperative planning, improved patient outcomes, and decreased overall healthcare cost. We believe that FFF 3D printing of customized PEEK implants could become an integral part of the hospitals and holds potential for various reconstructive surgery applications

Exploring the emerging design territory of construction 3D printing - project led architectural research

3D printing techniques (also known as additive fabrication) are maturing and increasingly being used as an alternative means for niche product manufacturing. These fabrication techniques are now being scaled up and adapted for full-scale fabrication within the construction industry. While it has been suggested that construction 3D printing (fabrication of construction elements using scaled up 3D printing machines) could lead to significant advances within the construction industry, there are currently few examples of how such advances could be achieved at a building scale. Although there has been significant effort invested in the development of construction 3D printing techniques, little detailed architectural design exploration has been published to establish methods for its application within the construction industry. My central proposition is that further detailed architectural exploration, focused on design for construction 3D printing combined with off-site fabrication methods and digital design tools, is necessary to tease out the potentials and limitations of construction 3D printing techniques. This exegesis is split into two parts; the first part presents background research based on interviews, site visits and literature review, focused on the topics; design, off-site fabrication, digital design tools and 3D printing within construction and parallel industries (aerospace, automotive, manufacturing and shipbuilding). The second part of the exegesis presents case studies of three architectural projects, which I designed, focused on design for fabrication using construction 3D printing. These case studies include: Freefab, a visionary design for a high-rise apartment building on Sydney harbour, designed in 2004. And two new architectural projects: Villa Roccia, a rock inspired house to be built in Sardinia and (in)human habitat a speculative design for an artificial reef in the Red Sea. The original contribution of this research is in the primary field survey of practices and emerging trends within the construction and parallel industries. Original contributions are also made in the synthesis of selected practices identified from literature review and the field surveys to form novel design and construction methodologies. These methodologies have been tested through the design of unique architectural projects focused on fabrication using construction 3D printing