scholarly journals A new design approach for customised medical devices realized by additive manufacturing

2020 ◽  
Vol 14 (4) ◽  
pp. 1171-1178
Author(s):  
V. Ricotta ◽  
R. I. Campbell ◽  
T. Ingrassia ◽  
V. Nigrelli
Keyword(s):  
Additive Manufacturing ◽  
Medical Devices ◽  
Voronoi Tessellation ◽  
Parametric Modelling ◽  
Cad Model ◽  
Voronoi Tessellations ◽  
Research Activity ◽  
Cad Modelling ◽  
Generative Algorithms ◽  
Torsion Springs

AbstractThe aim of this work is the design of a new customised elbow orthosis completely realized by Additive Manufacturing and the development of generative algorithms for parametric modelling and creation of 3D patterns to be adapted to the CAD model. This work describes a method to perfect the design of a custom elbow orthosis. A reverse engineering approach has been used to digitalize the patient’s arm and the subsequent CAD modelling of the structure of the custom elbow orthosis has been performed. In particular, two algorithms have been implemented for the creation of 3D patterns and Voronoi tessellations. Subsequently, FEM analyses have been carried out to validate the design. Finally, a prototype of the elbow orthosis with Voronoi tessellation has been realized by means of the SLS technology. The results obtained have demonstrated that the implemented algorithm solved the problems found during CAD modelling with conventional software. Furthermore, the results of FEM analyses have validated the design choices. All this allowed realizing the prototype by AM technologies without problems. Moreover, the new proposed modelling approaches allows creating, in an interactive way, patterns on complex surfaces. The results of this research activity present innovative elements of originality in the CAD modelling sector, which can contribute to solving problems related to the modelling for Additive Manufacturing. Furthermore, another innovative characteristic of the device is the use of torsion springs that simulate the action of physiotherapists during exercises for patient rehabilitation.

scholarly journals Additively manufactured textiles and parametric modelling by generative algorithms in orthopaedic applications

2020 ◽  
Vol 26 (5) ◽  
pp. 827-834 ◽  
Author(s):  
Vito Ricotta ◽  
Robert Ian Campbell ◽  
Tommaso Ingrassia ◽  
Vincenzo Nigrelli
Keyword(s):  
Computer Aided Design ◽  
Selective Laser Sintering ◽  
Flexible Structure ◽  
Parametric Modelling ◽  
Content Type ◽  
Cad Modelling ◽  
Generative Algorithms ◽  
Application Fields ◽  
Aided Design ◽  
Design And Production

Purpose The purpose of this paper is to implement a new process aimed at the design and production of orthopaedic devices fully manufacturable by additive manufacturing (AM). In this context, the use of generative algorithms for parametric modelling of additively manufactured textiles (AMTs) also has been investigated, and new modelling solutions have been proposed. Design/methodology/approach A new method for the design of customised elbow orthoses has been implemented. In particular, to better customise the elbow orthosis, a generative algorithm for parametric modelling and creation of a flexible structure, typical of an AMT, has been developed. Findings To test the developed modelling algorithm, a case study based on the design and production of an elbow orthosis made by selective laser sintering was investigated. The obtained results have demonstrated that the implemented algorithm overcomes many drawbacks typical of the traditional computer aided design (CAD) modelling approaches. The parametric CAD model of the orthosis obtained through the new approach is characterised by a flexible structure with no deformations or mismatches and has been effectively used to produce the prototype through AM technologies. Originality/value The obtained results present innovative elements of originality in the CAD modelling sector, which can contribute to solving problems related to modelling for AM in different application fields.

Analysis and CAD modelling of a new geometric spiroid hob

2015 ◽  
Vol 6 (2) ◽  
pp. 89-93
Author(s):  
S. Bodzás ◽  
I. Dudás
Keyword(s):  
Computer Modelling ◽  
Cad Model ◽  
Axial Section ◽  
Cad Modelling ◽  
Definition Of

The objectives of this publication are the analysis of surfaces and edges of a new geometric spiroid hob with arched profile in axial section and the definition of their equations for computer modelling. On the basis of this we will work out the CAD model of hob for our further geometric calculations.

scholarly journals Chain Reaction

2018 ◽  
Vol 140 (10) ◽  
pp. 30-35 ◽  
Author(s):  
Alan S. Brown
Keyword(s):  
Supply Chain ◽  
Additive Manufacturing ◽  
Supply Chains ◽  
Medical Devices ◽  
Business Models ◽  
Rolling Stock ◽  
Industrial Equipment ◽  
Special Report ◽  
Chain Reaction ◽  
The U.S

For 30 years, additive manufacturing has made all sorts of promises. Yet machines remained slow, materials expensive, and printers too inconsistent for critical parts. And additive was costly. Today, however, the technology is turning that past on its head. While additive manufacturing is usually the most expensive way to make any part, it makes economic sense for supply chains. Which is why manufacturers of everything from aircraft and rolling stock to appliances, industrial equipment, and medical devices are looking at 3-D supply chain solutions—as are the U.S. Marines and UPS. This special report looks at how additive manufacturing is disrupting business models and transforming supply chains.

scholarly journals Volume degeneracy of the typical cell and the chord length distribution for Poisson-Voronoi tessellations in high dimensions

2008 ◽  
Vol 40 (04) ◽  
pp. 919-938 ◽  
Author(s):  
Kasra Alishahi ◽  
Mohsen Sharifitabar
Keyword(s):  
Space Dimension ◽  
Voronoi Tessellation ◽  
Length Distribution ◽  
Chord Length ◽  
Voronoi Tessellations ◽  
Constant Intensity ◽  
Chord Length Distribution ◽  
Typical Cell ◽  
Centered Ball ◽  
Contact Distribution

This paper is devoted to the study of some asymptotic behaviors of Poisson-Voronoi tessellation in the Euclidean space as the space dimension tends to ∞. We consider a family of homogeneous Poisson-Voronoi tessellations with constant intensity λ in Euclidean spaces of dimensions n = 1, 2, 3, …. First we use the Blaschke-Petkantschin formula to prove that the variance of the volume of the typical cell tends to 0 exponentially in dimension. It is also shown that the volume of intersection of the typical cell with the co-centered ball of volume u converges in distribution to the constant λ−1(1 − e−λu ). Next we consider the linear contact distribution function of the Poisson-Voronoi tessellation and compute the limit when the space dimension goes to ∞. As a by-product, the chord length distribution and the geometric covariogram of the typical cell are obtained in the limit.

Laser Additive Manufacturing

3D Printing ◽  
2017 ◽  
pp. 154-171 ◽  
Author(s):  
Rasheedat M. Mahamood ◽  
Esther T. Akinlabi
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Computer Aided Design ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Cad Model ◽  
Laser Additive Manufacturing ◽  
Computer Aided ◽  
Manufacturing Technologies ◽  
Aided Design

Laser additive manufacturing is an advanced manufacturing process for making prototypes as well as functional parts directly from the three dimensional (3D) Computer-Aided Design (CAD) model of the part and the parts are built up adding materials layer after layer, until the part is competed. Of all the additive manufacturing process, laser additive manufacturing is more favoured because of the advantages that laser offers. Laser is characterized by collimated linear beam that can be accurately controlled. This chapter brings to light, the various laser additive manufacturing technologies such as: - selective laser sintering and melting, stereolithography and laser metal deposition. Each of these laser additive manufacturing technologies are described with their merits and demerits as well as their areas of applications. Properties of some of the parts produced through these processes are also reviewed in this chapter.

A Reverse Compensation Framework for Shape Deformation in Additive Manufacturing

2016 ◽  
Author(s):  
Kai Xu ◽  
Tsz-Ho Kwok ◽  
Yong Chen
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Shape Deformation ◽  
Cad Model ◽  
Complex Deformation ◽  
Physical Measurements ◽  
Building Process ◽  
Aided Design ◽  
Thermal Cooling ◽  
And Control

Shape deformation is an important issue in additive manufacturing (AM) processes such as the projection-based Stereolithography. Volumetric shrinkage and thermal cooling during the photopolymerization process combined with other factors such as the layer-constrained building process lead to complex deformation that is difficult to predict and control. In this paper, a general reverse compensation method and related computation framework are presented to reduce the shape deformation of AM fabricated parts. During the reverse compensation process, the shape deformation is calculated based on physical measurements of shape deformation. A novel method for identifying the correspondence between the deformed shape and the given nominal computer-aided design (CAD) model is presented based on added markers. Accordingly, a new CAD model based on the shape deformation and related compensation is computed. The intelligently revised CAD model by going through the same building process can result in a fabricated part that is close to the nominal CAD model. Two test cases have been designed to demonstrate the effectiveness of the presented method and the related computation framework. The shape deformation in terms of L2- and L∞-norm based on measuring the geometric errors is reduced by 40–60%.

Contact and chord length distribution of a stationary Voronoi tessellation

1998 ◽  
Vol 30 (03) ◽  
pp. 603-618 ◽  
Author(s):  
Lothar Heinrich
Keyword(s):  
Point Process ◽  
Voronoi Tessellation ◽  
Pair Correlation ◽  
Length Distribution ◽  
Distribution Functions ◽  
Chord Length ◽  
Closed Form Expression ◽  
Voronoi Tessellations ◽  
Chord Length Distribution ◽  
Contact Distribution

We give formulae for different types of contact distribution functions for stationary (not necessarily Poisson) Voronoi tessellations in ℝ d in terms of the Palm void probabilities of the generating point process. Moreover, using the well-known relationship between the linear contact distribution and the chord length distribution we derive a closed form expression for the mean chord length in terms of the two-point Palm distribution and the pair correlation function of the generating point process. The results obtained are specified for Voronoi tessellations generated by Poisson cluster and Gibbsian processes, respectively.

Contact and chord length distribution of a stationary Voronoi tessellation

1998 ◽  
Vol 30 (3) ◽  
pp. 603-618 ◽  
Author(s):  
Lothar Heinrich
Keyword(s):  
Point Process ◽  
Voronoi Tessellation ◽  
Pair Correlation ◽  
Length Distribution ◽  
Distribution Functions ◽  
Chord Length ◽  
Closed Form Expression ◽  
Voronoi Tessellations ◽  
Chord Length Distribution ◽  
Contact Distribution

We give formulae for different types of contact distribution functions for stationary (not necessarily Poisson) Voronoi tessellations in ℝd in terms of the Palm void probabilities of the generating point process. Moreover, using the well-known relationship between the linear contact distribution and the chord length distribution we derive a closed form expression for the mean chord length in terms of the two-point Palm distribution and the pair correlation function of the generating point process. The results obtained are specified for Voronoi tessellations generated by Poisson cluster and Gibbsian processes, respectively.

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