Functionally Graded Additive Manufacturing (FGAM) is a layer-by-layer fabrication process that involves gradationally varying the material organization within a component to achieve an intended function. FGAM establishes a radical shift from contour modelling to performance modelling by having the performance-driven functionality built directly into the material by strategically controlling the density and directionality of the substance or to combine materials together to produce a seamless monolithic structure. This paper presents a state-of-art conceptual understanding of FGAM, covering an overview of current techniques that can enable the production of FGAM parts as well as identifying current technological limitations and challenges. Possible strategies for overcoming those barriers are presented and recommendations on future design opportunities are discussed.

GmbH & Co. KG, and Rentokil Initial, of which some products are still manufactured and sold today. He is the Convenor for the International Organisation for Standardisation (ISO) TC261/WG4 group, leading Data Transfer and Design Standards for Additive Manufacturing, as well as holding various positions within ISO committee for Additive Manufacturing standards. Eujin is also a Chartered Technological Product Designer (CTPD) with Institution of Engineering Designers in the UK. 1.1 Entry-Level 3D Printers The Additive Manufacturing (AM) industry has had an impressive double-digit growth for the last 17 years (Wohler's report, 2014). There has been a strong demand for Entry-Level 3D Printers (EL3DPs) or low-cost desktop AM systems that are proliferating the market (Pei et al, 2011). Many of these are based on Fused Deposition Modelling (FDM) that uses the extrusion of molten thermoplastics. Other processes including Stereo-Lithography Apparatus (SLA), Digital Light Processing (DLP), Selective Heat Sintering (SHS) and Selective Laser Sintering (SLS) are gaining traction in the entry-level market. A key reason for the increasing popularity is that key patents such as those for FDM technologies have expired and the open-source movement is aligned with Arduino and Raspberry Pi micro-controllers that support universal access via free licensing. EL3DPs are often sold in a kit form, requiring basic tools and skills as compared to commercial machines that are enclosed and assembled (Marlone and Lipson, 2007). It has been recognised that the Fab@Home was the first opensource 3D printer that was specifically catered for the entry-level market, developed by Hod Lipson at Cornell University in 2006 and early models utilised a syringe-based deposition method (Fab@Home, 2014). Closer to the United Kingdom, the Rapman was developed by Adrian Bowyer from the University of Bath in 2009 (Jones et al, 2011). A key difference between the two systems was that the commercial version of the Rapman used a coiled filament that was cleaner and more cost effective (Lotz, Pienaar and de Beer, 2012). The first filament material that was developed for 3D printing was ABS (Acrylonitrile Butadiene Styrene). Although it comes in a variety of colours and is lightweight to transport, fumes of Acrylonitrile are produced, leading to health concerns (Stephens, et al 2013). In recent years, Poly-Lactic Acid (PLA) has been a more popular choice as it is biodegradable , has a lower melting point and more dimensionally stable as compared to ABS. Today, a wide plethora of filament materials are available including Nylon, High Impact Polystyrene (HIPS),

In the context of New Product Development (NPD), research has shown that not having a common understanding of Visual Design Representations (VDRs) has affected collaboration between industrial designers and engineering designers when working together. The aim of the research presented in this paper was two-fold. Firstly, to identify the representations employed by industrial designers and engineering designers during NPD from a literature survey. Secondly, to define and categorise these representations in the form of a taxonomy that is a systematic organisation of VDRs that are presently dispersed in the literature. For the development of the taxonomy, four measures encompassing orthogonality, spanning, completeness and usability were employed. It resulted in four groups consisting of sketches, drawings, models and prototypes. Validation was undertaken by means of an interview survey and further presenting the taxonomy at an international conference. The results showed that there were no issues raised by the respondents concerning the structure of the taxonomy or its components. KEYWORDSvisual design representations, industrial design, engineering design

Citation: BIN MAIDIN, S., CAMPBELL, R.I. and PEI, E., 2012. Development of a design feature database to support design for additive manufacturing.

The COVID-19 pandemic has caused a surge of demand for medical supplies and spare parts, which has put pressure on the manufacturing sector. As a result, 3D printing communities and companies are currently operating to ease the breakdown in the medical supply chain. If no parts are available, 3D printing can potentially be used to produce time-critical parts on demand such as nasal swabs, face shields, respirators, and spares for ventilators. A structured search using online sources and feedback from key experts in the 3D printing area was applied to highlight critical issues and to suggest potential solutions. The prescribed outcomes were estimated in terms of cost and productivity at a small and large scale. This study analyzes the number and costs of parts that can be manufactured with a single machine within 24 h. It extrapolates this potential with the number of identical 3D printers in the world to estimate the global potential that can help practitioners, frontline workers, and those most vulnerable during the pandemic. It also proposes alternative 3D printing processes and materials that can be applicable. This new unregulated supply chain has also opened new questions concerning medical certification and Intellectual property rights (IPR). There is also a pressing need to develop new standards for 3D printing of medical parts for the current pandemic, and to ensure better national resilience.

Abstract4D printing utilizes additive manufacturing methods to produce stimulus-responsive components that can change its shape from one to another when subject to appropriate stimuli. The use of 4D printing technology is expected to significantly become more widespread with more applications across bio-medical, aerospace, and defence industries. This paper discusses emerging applications for 4D printing and suitable stimulus-responsive materials for 4D printing. In terms of designing for 4D printing, aspects of the shape memory effect (SME) including one-way SMEs, two-way SMEs and three-way SMEs are presented. Materials and structures in the form of homogenous compositions and heterogeneous compositions are discussed, as well as different types of shape-shifting behaviours such as self-folding, self-assemblies, and self-dis-assemblies. Finally, current software and examples are presented together with the existing limitations that need to be overcome to achieve widespread adoption of 4D printing.

Purpose:This article reviews state-of-the-art developments in 4D printing, discusses what it is, investigates new applications that have been discovered and suggests its future impact Approach:The article clarifies the definition of 4D printing and describes notable examples covering material science, equipment and applications Findings:This paper highlights an emerging technology cycle where 4D printing research has gained traction within additive manufacturing. The use of stimuli-responsive materials can be programmed and printed to enable pre-determined reactions when subject to external stimuli

The fourth dimension in 4D printing refers to the ability of materials to alter its form after they are produced, thereby providing additional functional capabilities and performance driven applications. Stimuli materials provide this capability through the use of shape memory polymers. For this research, the property of programming the determined shape is achieved through controlled heat under laboratory conditions. This paper shows the potential to process and experiment with thermoplastic polyurethane as a shape memory material. Taking a step further, we ascertain the properties of this material through extrusion-based additive manufacturing processes and produce parts for testing. The results show that the characteristics of the 3D printed parts successfully retain the property of the shape memory and the recovery force allows this to be utilised as a mechanical actuator. The recovery stress has been recorded to be between 0.45 MPa and 0.61 MPa (at feed rate 990 mm/min).The maximum level of recovery stress is similar to the same material being processed through conventional compression moulding. Lastly, we designed and produced a coil as an actuator to demonstrate that the same material can be extended to other applications.