Rapid Prototyping Applications Research Articles

The design of scaffolds for use in tissue engineering. Part II. Rapid prototyping techniques.

Tissue engineering (TE) is an important emerging area in biomedical engineering for creating biological alternatives for harvested tissues, implants, and prostheses. In TE, a highly porous artificial extracellular matrix or scaffold is required to accommodate mammalian cells and guide their growth and tissue regeneration in three-dimension (3D). However, existing 3D scaffolds for TE proved less than ideal for actual applications because they lack mechanical strength, interconnected channels, and controlled porosity or pores distribution. In this paper, the authors review the application and advancement of rapid prototyping (RP) techniques in the design and creation of synthetic scaffolds for use in TE. We also review the advantages and benefits, and limitations and shortcomings of current RP techniques as well as the future direction of RP development in TE scaffold fabrication.

Characterization of SLS parts for drug delivery devices

There are many applications for rapid prototyping systems and application in the biomedical field is an important domain. Uses selective laser sintering (SLS) in this study to build porous cylindrical disc matrices for use as drug delivery devices (DDD). Studies the part‐bed temperature to ascertain its influence over the porosity of the disc matrices. They are found to have an inverse linear relationship. Also investigates the dense walls, the inherent consequences of building porous structures with the SLS, in the disc matrix as they have a direct impact on the performance of the DDD. Discusses the size constraint of the disc matrix due to the limitations of the SLS process. Also investigates the possibility of creating disc matrices of varying porosity. Experimental results demonstrate that SLS is viable in producing DDDs that have variable porosity and micro‐features.

Non-uniform offsetting and hollowing objects by using biarcs fitting for rapid prototyping processes

This paper presents a new method of using non-uniform offsetting and biarcs fitting to hollow out solid objects or thick walls to speed up the part building processes on rapid prototyping (RP) systems. Building a hollowed prototype instead of a solid part can significantly reduce the material consumption and the build time. A rapid prototyped part with constant wall thickness is important for many different applications of rapid prototyping. To provide the correct offset wall thickness, we develop a non-uniform offsetting method and an averaged surface normals method to find the correct offset contours of the stereolithography (STL) models. Detailed algorithms are presented to eliminate self-intersections, loops and irregularities of the offsetting contours. Biarcs fitting is used to generate smooth cross-section boundaries and offset contours for RP processes. Implementation results show that the developed techniques can generate smoothed slicing contours with accuracy for rapid prototyping without suffering from handling the huge number of linear segments of the traditional methods.

Automotive Applications of Rapid Prototyping for Active Vibration Control

This paper presents some recent results of Continental's research and development activities in the area of active vibration control. First, a brief overview of different approaches to active noise and vibration control is given. This is followed by a discussion of the rapid controller prototyping process that is currently being introduced. Finally, some experimental results obtained in cooperation with an automobile manufacturer are presented. These results demonstrate that major noise and vibration attenuation can be achieved through active vibration control in automobiles.

Fabrication of Non-Assembly Mechanisms and Robotic Systems Using Rapid Prototyping

In this paper, the application of Rapid Prototyping in fabricating non-assembly robotic systems and mechanisms is presented. Using two Rapid Prototyping techniques, Stereolithography and Selective Laser Sintering, prototypes of mechanical mobile joints were fabricated. The designs of these component joints were then used to fabricate the articulated structure of experimental prototypes for two robotic systems: (1) a three-legged parallel manipulator, (2) a four degree-of-freedom finger of a five-fingered robotic hand. These complex multi-articulated, multi-link, multi-loop systems have been fabricated in one step, without requiring assembly while maintaining their desired mobility. The feasibility and usefulness of Rapid Prototyping as a method for the fabrication of these non-assembly type mechanisms and robotic systems is the focus of this work.

Scheduling for Concept-Oriented Rapid Prototyping

In this paper scheduling strategies for a rapid prototyping system are discussed. Our rapid prototyping system is able to deal with several CASE-tools and generate code for models of heterogenous domains. By using the emerging CASE Data Interchange Format CDIF the model data of CASE-tools is represented tool-independent. This tool-independent layer serves as a basis for analysis, simulation and code generation. The generated code is partitioned in tasks which must be scheduled as fast as possible using a real-time operating system to support high performance applications. We classify scheduling requirements for the constraints of rapid prototyping and present a new scheduling strategy called pseudo-rate scheduling which significantly improve the execution speed of rapid prototyping applications. Additionally, we provide a set of equations to estimate schedulability. Experimental results demonstrate the main advantages of our scheduling strategy.

Virtual processing – application of rapid prototyping for visualization of metal forming processes

The objective of the study was to build physical models (prototypes) of a product based on finite element (FE) process simulations to aid product engineering in the evaluation of the manufacturing ability of the product. A methodology and two computer programs were developed to translate the FE geometrical information into a geometric representation acceptable by most rapid prototyping (RP) systems. In the case of the ERC/NSM, the prototypes are built with a fused deposition modeling (FDM) machine. This report has been focused in the production of physical models based on the FE simulation results for sheet and billet forming processes. However, the programs can be used with other process simulations as well.

Feature-based robot machining for rapid prototyping

This paper presents the development of a robot machining centre for rapid prototyping (RP) applications. Given a three-dimensional model of an object, surface features of the model were extracted and analysed. Cutter paths for both rough and finish cutting were then generated on the basis of the extracted surface features. In order to detect collision between the robot arm and its environment, an accurate model was built using a computer aided design (CAD) system and the Denavit-Hartenberg (D-H) notation was used to represent the robot arm transformation matrix. When collision was detected for a given contact point, both cutter location and robot arm positions were modified. A simple ship model was machined to demonstrate the effectiveness of the robot machining centre. Finally machining errors were quantified with the use of a coordinate measuring machine (CMM).

IBM VisualAge for Java

This paper introduces the IBM VisualAge® for JavaTM product, a robust, visual suite of tools designed for rapid prototyping and enterprise application development. The paper outlines the development-time benefits of using VisualAge for Java.

Hexapods to take over?

A man with a mission is Ghassan Matar, managing director of Geodetic Technology International, a company that is beginning to make its mark in rapid prototyping and machine tool applications. But that is just the beginning. The hexapod technology used in its machines can be turned equally to any application requiring a volumetric repeatability of 10µm at the working end, and the end effector can be a milling cutter, a gripper, a water jet cutter, a laser or other device. Jack Hollingum went to meet him and Eric Harris, product specialist.

Rapid prototyping trends

Analyses the market for rapid prototyping equipment and reports on the rapid growth that this market has experienced over the last ten years. Highlights the companies that are winning business and the technologies that are influencing growth. Describes applications of rapid prototyping for automotive parts, pharmaceutical pill bottles and jewellery design. Reports on new technology used by recently introduced low‐cost 3D printing machines for concept modelling and outlines new materials that have been developed to improve the performance and functionality of prototypes.

Technology forecast on ink‐jet head technology applications in rapid prototyping

Presents a technology forecast for ink‐jet head technology in 3D printers used in rapid prototyping. Gathers information via an expert opinion survey and from the Georgia Tech Library and the World Wide Web about future development and possible impacts. Shows that the technology is still in its infancy but receiving increased interest. Predicts the path the market may take and presents an outcome table for impact assessment. Considers the potential role of public policy in the technology development.

Features Rapid growth for rapid prototyping

Describes applications of rapid prototyping in the automotive, healthcare and jewellery industries. Explains how Ford Motor Co.’s use of RP technology has evolved since it first used stereolithography in 1988. Outlines the benefits of RP applications in jewellery design and how RP helped Smith & Nephew to arrive at the optimum bottle shape for a new healthcare product.

Reconstruction of volume boundary from layers by triangulation

Abstract Volume boundary reconstruction from a stack of layers is necessary for process planning tasks such as determination of the optimal part orientation and nesting if a model is represented by layer contours. This paper presents a new algorithm for this purpose. The algorithm is able to construct a valid solid boundary satisfying the manifold solid condition while maintaining the capability of creating a smooth boundary. The reconstruction problem is reduced to that of reconstructing a boundary between two adjacent layers. Thus, first are calculated the intersection points of contours of two layers on the layer plane. Then the minimum volume criterion is introduced and yields two kinds of sets of planar straight-line graphs (PSLGs) from the Boolean difference operation between layer contours. These sets of PSLGs are separately triangulated in 2-D. The solid boundary finally results from inserting additional triangles into the triangulation by analyzing the connectivity of the triangulation in 3-D. Unlike most previous approaches, the algorithm does not distinguish between single and multiple contours and does not need any special treatments such as the introduction of intuitive bridges between contours or simplifying contours with holes for handling complex geometric situations. The robustness of the algorithm has been demonstrated by many practical examples from medical imaging, rapid prototyping, and reverse engineering applications.

Preliminary experience with medical applications of rapid prototyping by selective laser sintering

Rapid prototyping techniques, originally developed for building components from computer aided designs in the motor industry, are now being applied in medicine to build models of human anatomy from high resolution multiplanar imaging data such a computed tomography (CT). The established technique of stereolithography and the more recent selective laser sintering (SLS), both build up an object layer by layer. Models have applications in surgical planning, for the design of customised implants and for training. Preliminary experience of using the SLS technique for medical applications is described, addressing questions regarding image processing, data transfer and manufacture. Pilot models, built from nylon, included two skulls (a child with craniosynostosis and an adult with hypertelorism) and a normal femur which was modelled for use in a bioengineering test of an artificial hip. The dimensions of the models were found to be in good agreement with the CT data from which they were built—for the child's skull the difference between the model and the CT data was less than 1.0±0.5 mm in each direction. Our experience showed that, with care, a combination of existing software packages may be used for data conversion. Ideally, image data of high spatial resolution should be used. The pilot models generated sufficient clinical interest for the technique to be pursued in the orthopaedic field.

Principles of Maude

This paper introduces the basic concepts of the rewriting logic language Maude and discusses its implementation. Maude is a wide-spectrum language supporting formal specification, rapid prototyping, and parallel programming. Maude's rewriting logic paradigm includes the functional and object-oriented paradigms as sublanguages. The fact that rewriting logic is reflective leads to novel metaprogramming capabilities that can greatly increase software reusability and adaptability. Control of the rewriting computation is achieved through internal strategy languages defined inside the logic. Maude's rewrite engine is designed with the explicit goal of being highly extensible and of supporting rapid prototyping and formal methods applications, but its semi-compilation techniques allow it to meet those goals with good performance.

An Overview of Thermal Spray Processes

The thermal spray process, once the key to the aerospace industry, offers potential solutions to many industrial coating problems. Th ese include the spraying of bioceramic materials, such as hydroxyapatite, by the medical industry, and the regalvanizing of welded seams by tube and pipe manufacturers. Some research institutions are investigating the possibilities of integrating thermal spray with stereolithography for rapid prototyping applications. The various thermal spray processes, coating characteristics, and the finishing requirements of coatings applied with the thermal spray process are reviewed.

SQLGEN: A framework for rapid client-server database application development

SQLGEN is a framework for rapid client-server relational database application development. It relies on an active data dictionary on the client machine that stores metadata on one or more database servers to which the client may be connected. The dictionary generates dynamic Structured Query Language (SQL) to perform common database operations; it also stores information about the access rights of the user at log-in time, which is used to partially self-configure the behavior of the client to disable inappropriate user actions. SQLGEN uses a microcomputer database as the client to store metadata in relational form, to transiently capture server data in tables, and to allow rapid application prototyping followed by porting to client-server mode with modest effort. SQLGEN is currently used in several production biomedical databases.

SQLGEN: A framework for rapid client-server database application development

SQLGEN is a framework for rapid client-server relational database application development. It relies on an active data dictionary on the client machine that stores metadata on one or more database servers to which the client may be connected. The dictionary generates dynamic Structured Query Language (SQL) to perform common database operations; it also stores information about the access rights of the user at log-in time, which is used to partially self-configure the behavior of the client to disable inappropriate user actions. SQLGEN uses a microcomputer database as the client to store metadata in relational form, to transiently capture server data in tables, and to allow rapid application prototyping followed by porting to client-server mode with modest effort. SQLGEN is currently used in several production biomedical databases.

Design for manufacturing with generative production processes and a neutral test environment

Different prototypes for design, ergonomics, assembly feasibility studies, etc. are employed in the various phases of product development. Starting from a basic idea the target features of the product are defined. From these product features the target features of the prototype must be defined and suitable processes selected. More and more companies are using generative production processes (GPP) to make these prototypes and furthermore the number of GPP is increasing. This paper describes a systematic method similar to quality function deployment (QFD) methods for carrying out these process steps. The feasibility (time and costs) of the rapid prototyping (RP) application depends to a large extent on the correct decision but also on the nature and quality of the product data given to the contract suppliers. The designer must therefore be in a position to evaluate the RP-specific quality of his design and to provide the supplier with optimized data. Product development costs can be effectively reduced by employing a neutral test environment to verify the GPP suitability of the generated product data.