Search results

The aim of this paper is to show how models fabricated via stereolithography (SL) served as “functional prototypes” for the redesign and optimisation of the spraying arm of a small dishwashing machine. The redesign process depended entirely on systematic experimental testing. SL modelling was employed in order to realise the various geometries proposed for the “new” spraying arm. The SL built spraying arm models (prototypes) themselves were used in the actual experiments, i.e. during the various dishwashing cycles. Their behaviour was very satisfactory. The methodology followed is presented in a systematic way. Aspects such as the effect of various build parameters on the models' functionality as well as “engineering solutions” given to problems encountered during fabrication and testing of the models are discussed in detail.

The purpose of this paper is to investigate the applicability and effectiveness of Stereolithography rapid prototyping to the field of scale modelling for architectural design evaluation and demonstration purposes. Two scale models concerning a modern renovated track and field sports facility and a reconstructed ancient stadium are examined. Both models were constructed by assembling together resin parts fabricated with Stereolithography instead of milling. Critical issues encountered during the building phase of the two models are addressed and presented in detail. Comments are made on the CAD requirements of the parts geometry, on the part building and the post‐processing phases as well as on the end achieved accuracy. Problems associated with the computational time, related to the 3‐D solid modelling, and with the physical properties of the parts, are also discussed. The present Stereolithography methodology is compared to conventional model building techniques by investigating efficiency and productivity factors, quality matters and time requirements.

The study aims to investigate the impact of additive manufacturing (AM) on the performance of a spare parts supply chain with a particular focus on underlying spare part demand patterns.

This work evaluates various AM-enabled supply chain configurations through Monte Carlo simulation. Historical demand simulation and intermittent demand forecasting are used in conjunction with a mixed integer linear program to determine optimal network nodal inventory policies. By varying demand characteristics and AM capacity this work assesses how to best employ AM capability within the network.

This research assesses the preferred AM-enabled supply chain configuration for varying levels of intermittent demand patterns and AM production capacity. The research shows that variation in demand patterns alone directly affects the preferred network configuration. The relationship between the demand volume and relative AM production capacity affects the regions of superior network configuration performance.

This research makes several simplifying assumptions regarding AM technical capabilities. AM production time is assumed to be deterministic and does not consider build failure probability, build chamber capacity, part size, part complexity and post-processing requirements.

This research is the first study to link realistic spare part demand characterization to AM supply chain design using quantitative modeling.

An important challenge of the osteotomy procedures, particularly in the case of large and complex corrections, is the fixation of the osteotomy site. The purpose of this study is to propose a practical and cost-effect methodology for the plate adapting problem of osteotomy surgery.

A novel patient-specific plate contouring methodology, based on rapid prototyping (RP) and multi-point forming (MPF) techniques, was developed and evaluated. In this methodology, a female mold is fabricated by RP, based on the geometry of the osteotomy site and estimation of the plate spring back. The mold is then used to configure a MPF die, which is then used for press forming of the factory-made locking plate. The applicability of the methodology was assessed in two case studies.

The results of implementing the methodology on a femoral and a tibial locking plate indicated very good conformity with the underlying bone, in both the frontal and sagittal planes. The surgical application of the pre-operatively contoured tibial plate facilitated the plate locating and screw inserting procedures, and provided a secure fixation for bone fragments.

The results are promising and provide a proof of concept for the feasibility and applicability of the proposed methodology in clinical practice, as a complementary to the existing surgical preplanning and patient-specific instrument preparations.

The advantageous features of RP and the MPF were used to provide a solution for the plate adapting problem of osteotomy surgery.

This paper aims to provide an overview of applications of medical rapid prototyping (MRP)-assisted customized surgical guides (CSGs) and shows the potential of this technology in complex surgeries. This review paper also reports two case studies from open literature where MRP-assisted CSGs have been successfully used in complex surgeries.

Key publications from the past two decades have been reviewed.

This study concludes that the use of MRP-assisted CSGs improves the accuracy of surgery. Additionally, MRP-assisted CSGs make the surgery much faster, accurate and cheaper than any other technique. The outcome based on literature review and two case studies strongly suggested that MRP-assisted CSGs might become part of a standard protocol in the medical sector to operate the various complex surgeries, in the near future.

Advanced technologies like radiology, image processing, virtual surgical planning (VSP), computer-aided design (CAD) and MRP made it possible to fabricate the CSGs. MRP-assisted CSGs can easily transfer the VSP into the actual surgery.

This paper is beneficial to study the development and applications of MRP-assisted CSGs in complex surgeries.

This paper aims to present a pilot study’s aims to identify opportunities and limits deriving from the use of low-cost 3D printing (3DP), fused deposition modelling (FDM), open-source technologies in co-design and co-production processes involving persons with rheumatic diseases (RDs).

In the paper, the authors outline why the use of low-cost, entry-level FDM can be meaningful for this scenario, implying a complete sharing of the design and the production phases of small assistive devices. The +TUO process is composed of several stages, among which the generative session represents the core.

This study highlights as the introduction of this low-cost technology in co-generative processes with people with RDs is a real challenge that can lead to new products and solutions, and that can sustain a social and local manufacturing approach for people facing a specific disablement.

This research is a first step of a broader research, new researches are going to explore further details related with the technology and of the adopted method.

Involving actively, the end user during the creation process can bring advantages such as meeting more precisely their needs and create innovative products, as shown in the text.

For people living with RDs, an occupation is important to sustain a process of empowerment. Adopting assistive devices supports daily activities and facilitates the occupation.

+TUO is a pilot study that explore a topic already discussed in the scientific arena, without focusing on the specific use of low-cost 3DP technologies.

This paper aims to present the methodology and results of the experimental characterization of three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) parts utilizing digital image correlation (DIC).

Tensile and shear characterizations of ABS and PC 3D-printed parts were performed to determine the extent of anisotropy present in 3D-printed materials. Specimens were printed with varying raster ([+45/−45], [+30/−60], [+15/−75] and [0/90]) and build orientations (flat, on-edge and up-right) to determine the directional properties of the materials. Tensile and Iosipescu shear specimens were printed and loaded in a universal testing machine utilizing two-dimensional (2D) DIC to measure strain. The Poisson’s ratio, Young’s modulus, offset yield strength, tensile strength at yield, elongation at break, tensile stress at break and strain energy density were gathered for each tensile orientation combination. Shear modulus, offset yield strength and shear strength at yield values were collected for each shear combination.

Results indicated that raster and build orientations had negligible effects on the Young’s modulus or Poisson’s ratio in ABS tensile specimens. Shear modulus and shear offset yield strength varied by up to 33 per cent in ABS specimens, signifying that tensile properties are not indicative of shear properties. Raster orientation in the flat build samples reveals anisotropic behavior in PC specimens as the moduli and strengths varied by up to 20 per cent. Similar variations were observed in shear for PC. Changing the build orientation of PC specimens appeared to reveal a similar magnitude of variation in material properties.

This article tests tensile and shear specimens utilizing DIC, which has not been employed previously with 3D-printed specimens. The extensive shear testing conducted in this paper has not been previously attempted, and the results indicate the need for shear testing to understand the 3D-printed material behavior fully.

The purpose of this paper is to investigate a method for comparing the scanning and reproducing accuracy of highly shaped objects like plaster casts used in dentistry.

Theoretical considerations on errors introduced by the scanning systems and subsequent point clouds data elaboration have led to a method to estimate the accuracy of the whole process. Suitable indices have been chosen and computed at each stage. As a final result, the overall chain, scanning and reproducing systems can be assessed. In order to validate the proposed method casts have been scanned by means of commercial systems and then reproduced by using different rapid prototyping technologies, materials and parameters. Error indices have been computed and reported.

Since it is not possible to define reliable and meaningful reference models for non‐standard shapes, an absolute accuracy value for the scanning process cannot be stated. Anyway the proposed method, thanks to relative performance indices, allows the comparison of different acquisition systems and the evaluation of the most performing manufacturing chain.

The study provides a method to assess the relative performance between commercial systems both in scanning and reproducing stage.

In literature, some studies on the accuracy of scanning devices have been found but they are based on standard geometrical features. In this paper, the problem of complex shapes in absence of reference model is addressed instead.

The purpose of this paper is to demonstrate that significant surface finish improvements can be accomplished in stereolithography (SL) fabricated parts by applying a new process planning method based on parameter estimation (PE).

PE is a method that finds a set of parameter values that minimize a measure of deviation. In this work, the measure of deviation is the difference between the exposure received by points along down‐facing surfaces and the SL resin's critical exposure.

The surface finish of down‐facing surfaces can be improved by a factor of 2‐9, depending upon the surface angle, compared with parts prepared using commercially available software. Surface finishes less than 1 μm Ra have been demonstrated on a SLA‐250/50 machine.

Only down‐facing surfaces can have their surface finish improved using this method.

Common form errors known as “stair‐stepping” can be diminished on parts fabricated using SL.

The usage of PE methods for process planning is a new approach.

This paper aims to convert surface data directly to a three-dimensional (3D) stereolithography (STL) part. The Geographic Information Systems (GIS) data available for a terrain are the data of its surface. It doesn’t have information for a solid model. The data need to be converted into a three-dimensional (3D) solid model for making physical models by additive manufacturing (AM).

A methodology has been developed to make the wall and base of the part and tessellates the part with triangles. A program has been written which gives output of the part in STL file format. The elevation data are interpolated and any singularity present is removed. Extensive search techniques are used.

AM technologies are increasingly being used for terrain modeling. However, there is not enough work done to convert the surface data into 3D solid model. The present work aids in this area.

The methodology removes data loss associated with intermediate file formats. Terrain models can be created in less time and less cost. Intricate geometries of terrain can be created with ease and great accuracy.

The terrain models can be used for GIS education, educating the community for catchment management, conservation management, etc.

The work allows direct and automated conversion of GIS surface data into a 3D STL part. It removes intermediate steps and any data loss associated with intermediate file formats.