Jo M. P. Geraedts

Optimal Design for Additive Manufacturing: Opportunities and Challenges

Additive Manufacturing (AM) represents a maturing collection of production technologies also known as rapid prototyping, rapid manufacturing and three-dimensional printing. One of the most promising aspects of AM is the possibility to create highly complex geometries. Despite a growing body of knowledge concerning the technological challenges, there is a lack of methods that allow designers to effectively deal with the new possibilities. This article presents a literature survey on the impact that AM can have on design. The survey was focused on the new opportunities of fabrication processes, the relationship between structure and performance, and optimization approaches. We applied Olsen’s three-link chain model to relate product structure with performance, linked by strength, stiffness, compliance, dynamic, thermal, and visual properties. We also use this model to base our proposed Design for Additive Manufacturing (DfAM) method. The findings show that there is a growing body of knowledge in the field of design for AM (DfAM), yet only considers a subset of properties. Furthermore, the knowledge on materials, computational optimization, computer aided design, and behavioral simulation embody separated domains and related software support. This is in contrast with design engineering, which requires a holistic approach to conceptualize new products.

Voxel-based fabrication through material property mapping

We present a bitmap printing method and digital workflow using multi-material high resolution Additive Manufacturing (AM). Material composition is defined based on voxel resolution and used to fabricate?a design object?with locally varying material stiffness, aiming to?satisfy the design objective. In this workflow voxel resolution is set by the printers native resolution, eliminating the need for slicing and path planning. Controlling geometry and material property variation at the resolution of the printer provides significantly greater control over structure-property-function relationships. To demonstrate the utility of the bitmap printing approach we apply it to the design of a?customized prosthetic socket. Pressure-sensing elements are concurrently fabricated with the socket, providing possibilities for evaluation of the sockets fit. The level of control demonstrated in this study?cannot be achieved using traditional CAD tools and volume-based AM workflows, implying that new CAD workflows must be developed in order to enable designers to harvest the capabilities of AM. Bitmap printing workflow enables digital fabrication in printers native resolution.Voxel-based design and representation of objects for multi-material printing.Using 3D printed light guides, deformation of materials can be sensed.

Topographical scanning and reproduction of near-planar surfaces of paintings

Paintings are near-planar objects with material characteristics that vary widely. The fact that paint has a material presence is often overlooked, mostly because we often encounter these artworks in the form of two-dimensional reproductions. Capturing paintings in the third dimension is not only important for study, restoration and conservation, but it also inspires 3D printing methods1, particularly through the high demands it makes on reproducing color, gloss and texture. “A hybrid solution between fringe projection and stereo imaging is proposed as 3D imaging method, with a setup involving two cameras and a projector. Fringe projection is aided by sparse stereo matching to serve as image encoder. These encoded images processed by the stereo cameras solve the correspondence problem in stereo matching, leading to a dense and accurate topographical map, while simultaneously capturing the composition of the painting in full color”1. The topographical map and color data are used to make hardcopy 3D reproductions, using a specially developed printing system. Several paintings by Dutch masters Rembrandt and Van Gogh have been scanned and reproduced using this technique. These 3D printed reproductions have been evaluated by experts, both individually and in a side-by-side comparison with the original.

Towards Behavior Design of a 3D-Printed Soft Robotic Hand

This work presents an approach to integrate actuators, sensors, and structural components into a single product that is 3D printed using Selective Laser Sintering. The behavior of actuators, sensors, and structural components is customized to desired functions within the product. Our approach is demonstrated by the realization of human-like behavior in a 3D-printed soft robotic hand. This work describes the first steps towards creating the desired behavior by means of modeling specific volumes within the product using Additive Manufacturing. Our work shows that it is not necessary to limit the design of a soft robotic product to only integrating off-the-shelf components but instead we deeply embedded the design of the required behavior in the process of designing the actuators, sensors, and structural components.

Characterizing the state of the art of human-robot coproduction

The industry is working towards manufacturing systems consisting of a blend of humans and robots. We look at the development of these systems in the context of Small and Medium Enterprises (SME). Also, it is believed that industrial robots with collaboration capabilities with humans will play a crucial role in the change towards reconfigurable and flexible manufacturing systems. Collaboration and teaming are natural social skills of humans. However, little is known about robots and their capabilities in working efficiently with these skills. From our review of the current context of manufacturing, we understand that tasks at a workstation are executed by a combination of various actors and there are many ways to design, control and simulate their interplay. These practices need to be developed for these novel systems as well. Through a survey of existing examples of similar systems, we set an initial step in generating knowledge on the parameters that influence the design of these systems. In these systems we see that humans and robots have certain areas and types of skills through which they engage in joint activity. We compare these examples from three perspectives and draw preliminary conclusions.

Reproducing oil paint gloss in print for the purpose of creating reproductions of Old Masters

In the field of Fine Art reproduction, 3D scanning plus 3D printing, combined with dedicated software, now allows to capture and reproduce the color and texture of oil paintings. However, for life-like reproduction of the material appearance of such paintings, the typical gloss and translucency must also be included, which is currently not the case. The aim of this paper is to elaborate on the challenges and results of capturing and reproducing oil paint gloss (next to texture and color) using a scanning and printing system. A sample was hand-made using oil paint and acrylic varnish, and its gloss was then reproduced. A gloss map of the painted sample was acquired using a high end DLSR camera and a simple acquisition protocol. Next, Océ High Resolution 3D printing technology was used to create samples with spatially varying gloss. For this, two different strategies were combined: (1) multilevel half-toning of the colors was used to reproduce matte color layers, and (2) varnish was half-toned on top in increasing coverage to recreate increasing gloss levels. This paper presents an overview of the state-of-the-art literature in gloss reproduction and perception, our process of reproduction as well as the visual evaluation of the quality of the created reproduction.

Exploring human robot coproduction

Recently, robots are making their way towards the small and medium enterprises at a quick pace. This is due to market demand and enabled by reduction in costs of robot systems. If robots can be introduced strategically in existing production workflows, productivity could be increased. However, the task division and interaction between human and robot co-workers need to be optimized in order to achieve this. This work-in-progress paper presents a pilot setup to explore such scenarios. We discuss early findings and we present our vision for the future of human robot coproduction.

Nanostructure and microstructure fabrication : from desired properties to suitable processes

When designing a new nanostructure or microstructure, one can follow a processing-based manufacturing pathway, in which the structure properties are defined based on the processing capabilities of the fabrication method at hand. Alternatively, a performance-based pathway can be followed, where the envisioned performance is first defined, and then suitable fabrication methods are sought. To support the latter pathway, fabrication methods are here reviewed based on the geometric and material complexity, resolution, total size, geometric and material diversity, and throughput they can achieve, independently from processing capabilities. Ten groups of fabrication methods are identified and compared in terms of these seven moderators. The highest resolution is obtained with electron beam lithography, with feature sizes below 5 nm. The highest geometric complexity is attained with vat photopolymerization. For high throughput, parallel methods, such as photolithography (≈101 m2 h-1 ), are needed. This review offers a decision-making tool for identifying which method to use for fabricating a structure with predefined properties.

ShowHow: A Flexible, Structured Approach to Commit University Stakeholders to Sustainable Development

This paper presents an alternative approach and preliminary results to developing a sustainable campus by connecting research, education and real estate management. It is coined ‘ShowHow’: the deployment and display of the knowhow of all stakeholders in a university. The approach is built upon five pillars: (1) Projects: the initiation of a variety of projects; (2) Intensive real estate involvement: the introduction of sustainability and innovation to all levels of real estate strategy and decision-making processes; (3) Programmatic themes: the development of multi-faculty, overarching programmatic themes; (4) Stakeholder integration: The involvement of and intense liaison and co-creation with real estate, facility management, professors, and students, and (5) Outreach: the provision of impetus for regional/national sustainability systems with campus projects. The results are encouraging: In a short period of time, one year, more than 20 projects have been developed, the board of the Real Estate department adopted sustainable development as a key value, three programmatic lines are under construction, personal connections between students, operational and scientific staff were established, and 2020 goals for greening the energy supply will be met in 2017. Additionally, the University also performs a catalyst role for regional sustainable heating transformations. New PhD positions could be established. This approach seems very promising, generating enthusiasm throughout the university. It has elements, typical for technical universities, but the formula may be replicated at other universities in general, by deploying non-technical knowhow, and by including existing local sustainability themes and opportunities.