Orthopedic Surgery Planning Based on the Integration of Reverse Engineering and Rapid Prototyping

This paper describes orthopedic surgical planning based on the integration of RE and RP. Using symmetrical characteristics of the human body, CAD data of the original bone without damages for the injured extent are generated from a mirror transformation of undamaged bone data for the uninjured extent. The physical model before the injury is manufactured from RP apparatus. Surgical planning, such as the selection of the proper implant, pre-forming of the implant, decision of fixation positions and incision sizes, etc., is determined by a physical simulation using the physical model. In order to examine the applicability and efficiency of surgical planning technology for orthopedics, various case studies, such as a proximal tibia plateau fracture, a distal tibia comminuted fracture and an iliac wing fracture of pelvis, are carried out. As a result of the examination, it has been shown that the orthopedic surgical planning based on the integration of RE and RP is an efficient surgical tool.Mechanical Engineerin

Biomimetic Design and Fabrication of Interior Architecture of Tissue Scaffolds Using Solid Freeform Fabrication

Modeling, design and fabrication of tissue scaffolds with intricate architecture, porosity and pore size for desired tissue properties presents a challenge in tissue engineering. This paper will present the details of our development in designing and fabrication of the interior architecture of scaffolds using a novel design approach. The Interior Architecture Design (IAD) approach seeks to generate scaffold layered freeform fabrication tool path without forming complicated 3D CAD scaffold models. This involves: applying the principle of layered manufacturing to determine the scaffold individual layered process planes and layered contour; defining the 2D characteristic patterns of the scaffold building blocks (unit cells) to form the Interior Scaffold Pattern; and the generation of process tool path for freeform fabrication of these scaffolds with the specified interior architecture. Feasibility studies applying the IAD algorithm to example models and the generation of fabrication planning instructions will be presented.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

Virtual assembly rapid prototyping of near net shapes

Virtual reality (VR) provides another dimension to many engineering applications. Its immersive and interactive nature allows an intuitive approach to study both cognitive activities and performance evaluation. Market competitiveness means having products meet form, fit and function quickly. Rapid Prototyping and Manufacturing (RP&M) technologies are increasingly being applied to produce functional prototypes and the direct manufacturing of small components. Despite its flexibility, these systems have common drawbacks such as slow build rates, a limited number of build axes (typically one) and the need for post processing. This paper presents a Virtual Assembly Rapid Prototyping (VARP) project which involves evaluating cognitive activities in assembly tasks based on the adoption of immersive virtual reality along with a novel non-layered rapid prototyping for near net shape (NNS) manufacturing of components. It is envisaged that this integrated project will facilitate a better understanding of design for manufacture and assembly by utilising equivalent scale digital and physical prototyping in one rapid prototyping system. The state of the art of the VARP project is also presented in this paper

Virtual bloXing - assembly rapid prototyping for near net shapes

Virtual reality (VR) provides another dimension to many engineering applications. Its immersive and interactive nature allows an intuitive approach to study both cognitive activities and performance evaluation. Market competitiveness means having products meet form, fit and function quickly. Rapid Prototyping and Manufacturing (RP&M) technologies are increasingly being applied to produce functional prototypes and the direct manufacturing of small components. Despite its flexibility, these systems have common drawbacks such as slow build rates, a limited number of build axes (typically one) and the need for post processing. This paper presents a Virtual Assembly Rapid Prototyping (VARP) project which involves evaluating cognitive activities in assembly tasks based on the adoption of immersive virtual reality along with a novel nonlayered rapid prototyping for near net shape (NNS) manufacturing of components. It is envisaged that this integrated project will facilitate a better understanding of design for manufacture and assembly by utilising equivalent scale digital and physical prototyping in one rapid prototyping system. The state of the art of the VARP project is also presented in this paper

Rotational 3D Printing of Sensor Devices using Reactive Ink Chemistries

This paper charts progress in three key areas of a project supported by both UK government and UK industry to manufacture novel sensor devices using rotary 3D printing technology and innovative ink chemistries; (1) the development of an STL file slicing algorithm that returns constant Z height 2D contour data at a resolution that matches the given print head setup, allowing digital images to be generated of the correct size without the need for scaling; (2) the development of image transformation algorithms which allow images to be printed at higher resolutions using tilted print heads and; (3) the formulation of multi part reaction inks which combine and react on the substrate to form solid material layers with a finite thickness. A Direct Light Projection (DLP) technique demonstrated the robustness of the slice data by constructing fine detailed three dimensional test pieces which were comparable to identical parts built in an identical way from slice data obtained using commercial software. Material systems currently under investigation include plaster, stiff polyamides and epoxy polymers and conductive metallic’s. Early experimental results show conductivities of silver approaching 1.42x105 Siemens/m.Mechanical Engineerin

Variable fused deposition modelling - concept design and tool path generation

Current Fused Deposition Modelling (FDM) techniques use fixed diameter nozzles to deposit a filament of plastic layer by layer. The consequence is that the same small nozzle, essential for fine details, is also used to fill in relatively large volumes. In practice a Pareto-optimal nozzle diameter is chosen that attempts to maximise resolution while minimising build time. This paper introduces a concept for adapting an additive manufacturing system, which exploits a variable diameter nozzle for the fused deposition of polymers. The variable nozzle allows the print resolution and the build speed to become independent variables which may be optimised. The paper discusses a concept design for the variable diameter nozzle to be fitted to a RapMan 3D printer and the software used to generate the tool paths for the extrusion head. The methodology involves the use of existing software solutions to gather basic data from STL files and generate the tool paths. A method for integrating the data and the deposition system is proposed. The challenges and possibilities of the technology are discussed as well as future research

Software Testbed for Selective Laser Sintering

Computer software plays an important role in the implementation of Solid Freeform Fabrication (SFF) technologies. This paper describes a software testbed for processing part geometry for a particular SFF technology, selective laser sintering (SLS), that is built around the separation of the slicing and rasterization operations to accommodate geometric information from a variety of sources. The paper also discusses the process control software being developed for a new high-temperat rkstation for SLS of metal powders. This program features a high-resolution data rmat, the ability to interpolate to achieve a desired resolution, and a menu-driven user interface with graphical feedback and process simulation capabilities.Mechanical Engineerin

The Clemson Intelligent Design Environment For Stereolithography-Cides 2.0

There are a large number of commercial Rapid Prototyping (RP) devices available today. All ofthese machines begin with a Computer-Aided Design (CAD) model, which is tessellated, sliced and then built layer-by-Iayer on the RP device. All ofthese operations, except the actual building ofthe part, are completed on a computer. Therefore, many improvements to the RP processes can be achieved through software, without affecting the RP devices or the warranties on them. This has led to the development of a front-end software product to support the task of preparing the part to be built. The Clemson Intelligent Design Environment for Stereolithography (CIDES) is a user-centered interface between the CAD system and RP systems, primarily the Stereolithography Apparatus (SLA). CIDES 2.0 is designed to provide a variety oftools which are valuable to the users ofRP systems, including the ability to view and modify tessellated (STL) files, generate supports, and slice STL files into layer (SLI) files for use on an SLA. It also provides the ability to view SLI and merged (V) files. Furthermore, CIDES offers additional translation capabilities that make it valuable for other RP processes. The package has proven useful in the Laboratory to Advance Industrial Prototyping (LAIP) at Clemson University. CIDES 2.0 is a new X Windows-based release based on the original version ofCIDES with many additional features. A new HumanComputer Interface is the major improvement to this release.Mechanical Engineerin

Computer Aspects of Solid Freeform Fabrication: Geometry, Process Control, and Design

Solid Freefonn Fabrication (SFF) is a class of manufacturing technologies aimed at the production of mechanical components without part-specific tooling or process planning. Originally used for creating modelsfor visualization, many industrial users of SFF technologies are realizing the greater potentialofSFF as legitimate manufacturing processes for producing patterns and, in some cases, functional.parts. Thus, SFF is becoming an important aspect of the product realization process in these industries. Solid Freefonn Fabrication arose from the dream of "push-button" prototyping, in which solid reproductions of three-dimensional geometric models are created automatically under computer control. Perhaps more than any other class of manufacturing technologies, computer software development has been an integral part of the emergence of SFF. As SFF technologies evolve toward the ability to create functional parts, computer issues gain more importance. This paper discusses three aspects of software design for SFF: processing of geometric data, global and local control of SFF processes, and computer-based analysis and design for SFF manufacturing. The discussion of geometric processing issues focuses on accuracy and completeness of input models, and the algorithms required to process such models. The interplay between the physics of SFF processing and the desired output geometry is discussed in terms of the development of model-based control algorithms for SFF. These two areas, geometric processing and control, are necessary for the practical implementation of any SFF technology. However, for SFF to realize its potential as an alternative for manufacturing functional parts, engineers must be provided with analysis and design tools for predicting mechanical properties, ensuring dimensional accuracy, choosing appropriate materials, selecting process parameter values, etc. For each of these three different but related areas of software design, the state-of-theart is assessed, contemporary research is summarized, and future needs are outlined.Mechanical Engineerin