On the Use of Angled, Dynamic Laser Beams to Improve Stereolithography Surface Finish

Improved surface finish of Stereolithography (SLA) parts is an important goal for furthering the resolution of the technology. In order to improve the surface finish, a dynamic laser beam with changing angle, beam size, beam shape, and irradiance distribution is proposed. In this paper, an analytical irradiance model of an angled, dynamic laser beam in the SLA process is presented. This model is used to simulate cured shapes of SLA builds. Simulated build shapes are compared to established SLA analytical models and conclusions are drawn on the accuracy of the developed model.Mechanical Engineerin

From 3D Models to 3D Prints: an Overview of the Processing Pipeline

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and Innovation action; Grant agreement N. 68044

Generation of Porous Structures Using Fused Deposition

The Fused Deposition Modeling process uses hardware and software machine-level language that are very similar to that of a pen-plotter. Consequently, the·use of patterns with poly-lines as basic geometric features, instead of the current method based on filled polygons (monolithic models), can increase its efficiency. In the current study, various toolpath planning methods have been developed to fabricate porous structures. Computational domain decomposition methods can be applied to the physical or to slice-level domains to generate structured and unstructured grids. Also, textures can be created using periodic tiling of the layer with unit cells (squares, honeycombs, etc). Methods 'based on curves include fractal space filling curves and.change of effective road width Within a layer or within a continuous curve. Individual phases can also be placed in binary compositions. In present investigation, a custom software has been developed and implemented to generate build files (SML) and slice files (SSL) for the above-mentioned structures, demonstrating the efficient control ofthe size, shape, and distribution ofporosity.Mechanical Engineerin

Enabling Inter-Repository Access Management between iRODS and Fedora

4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PresentationsDate: 2009-06-04 08:30 AM – 10:00 AMMany digital repositories have been built using different technologies such as Fedora and the integrated Rule-Oriented Data System (iRODS). This paper analyzes both the Fedora and iRODS technologies to understand how to integrate the two systems to enable cross-repository data sharing. The areas considered include the digital object model, services, management of distributed storage, external data resources, and policy enforcement.National Science Foundatio

Trade-off analysis and design of a Hydraulic Energy Scavenger

In the last years there has been a growing interest in intelligent, autonomous devices for household applications. In the near future this technology will be part of our society; sensing and actuating will be integrated in the environment of our houses by means of energy scavengers and wireless microsystems. These systems will be capable of monitoring the environment, communicating with people and among each other, actuating and supplying themselves independently. This concept is now possible thanks to the low power consumption of electronic devices and accurate design of energy scavengers to harvest energy from the surrounding environment. In principle, an autonomous device comprises three main subsystems: an energy scavenger, an energy storage unit and an operational stage. The energy scavenger is capable of harvesting very small amounts of energy from the surroundings and converting it into electrical energy. This energy can be stored in a small storage unit like a small battery or capacitor, thus being available as a power supply. The operational stage can perform a variety of tasks depending on the application. Inside its application range, this kind of system presents several advantages with respect to regular devices using external energy supplies. They can be simpler to apply as no external connections are needed; they are environmentally friendly and might be economically advantageous in the long term. Furthermore, their autonomous nature permits the application in locations where the local energy grid is not present and allows them to be ‘hidden' in the environment, being independent from interaction with humans. In the present paper an energy-harvesting system used to supply a hydraulic control valve of a heating system for a typical residential application is studied. The system converts the kinetic energy from the water flow inside the pipes of the heating system to power the energy scavenger. The harvesting unit is composed of a hydraulic turbine that converts the kinetic energy of the water flow into rotational motion to drive a small electric generator. The design phases comprise a trade-off analysis to define the most suitable hydraulic turbine and electric generator for the energy scavenger, and an optimization of the components to satisfy the systems specification

Procedural function-based modelling of volumetric microstructures

We propose a new approach to modelling heterogeneous objects containing internal volumetric structures with size of details orders of magnitude smaller than the overall size of the object. The proposed function-based procedural representation provides compact, precise, and arbitrarily parameterised models of coherent microstructures, which can undergo blending, deformations, and other geometric operations, and can be directly rendered and fabricated without generating any auxiliary representations (such as polygonal meshes and voxel arrays). In particular, modelling of regular lattices and cellular microstructures as well as irregular porous media is discussed and illustrated. We also present a method to estimate parameters of the given model by fitting it to microstructure data obtained with magnetic resonance imaging and other measurements of natural and artificial objects. Examples of rendering and digital fabrication of microstructure models are presented

Survey on Additive Manufacturing, Cloud 3D Printing and Services

Cloud Manufacturing (CM) is the concept of using manufacturing resources in a service oriented way over the Internet. Recent developments in Additive Manufacturing (AM) are making it possible to utilise resources ad-hoc as replacement for traditional manufacturing resources in case of spontaneous problems in the established manufacturing processes. In order to be of use in these scenarios the AM resources must adhere to a strict principle of transparency and service composition in adherence to the Cloud Computing (CC) paradigm. With this review we provide an overview over CM, AM and relevant domains as well as present the historical development of scientific research in these fields, starting from 2002. Part of this work is also a meta-review on the domain to further detail its development and structure

Technologies for rapid prototyping (RP) - basic concepts, quality issues and modern trends

The paper describes the basics of the 3D printing technologies for rapid prototyping (RP). It shows the benefits of their utilization in product design and manufacturing of conventional parts and items with medical and other application. The most mature RP principles are presented and compared.Some trends in developing new 3D printers and corresponding materials for micro/nano and biological applications are described.  Some modern budget platforms are suggested for technology users.The paper also provides a summary of the main quality issues in the layering technologies as well as methodologies for studying the process capabilities, accuracy and maturity

The Materials Advantage of the SLS Selective Laser Sintering Process

The rapid prototyping market continues to progress in tenns of processes and materials used for the creation of conceptual and functional parts and prototype tooling. As this market continues to mature, the market leaders win be able to offer rapid prototyping processes and materials that provide parts which are accurate, have good surface finish, and provide properties which support fqnctional applications.. The materials used for these parts will be. polymers, metals, and ceramics. '. The strength oithe SLSTM Selective Laser Sintering Process is the. potential to use a wide variety of powdered materials for the creation of models, patterns, and some fonns of prototype tooling. ,This paper will cover the types of materials currently used in the SLS process and their inherent advantages.and discuss current research into the development of new materials.Mechanical Engineerin