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Article
Publication date: 3 February 2023

Josué Costa-Baptista, Edith Roland Fotsing, Jacky Mardjono, Daniel Therriault and Annie Ross

The purpose of this paper is the design and experimental investigation of compact hybrid sound-absorbing materials presenting low-frequency and broadband sound absorption.

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Abstract

Purpose

The purpose of this paper is the design and experimental investigation of compact hybrid sound-absorbing materials presenting low-frequency and broadband sound absorption.

Design/methodology/approach

The hybrid materials combine microchannels and helical tubes. Microchannels provide broadband sound absorption in the middle frequency range. Helical tubes provide low-frequency absorption. Optimal configurations of microchannels are used and analytical equations are developed to guide the design of the helical tubes. Nine hybrid materials with 30 mm thickness are produced via additive manufacturing. They are combinations of one-, two- and four-layer microchannels and helical tubes with 110, 151 and 250 mm length. The sound absorption coefficient of the hybrid materials is measured using an impedance tube.

Findings

The type of microchannels (i.e. one, two or four layers), the number of rotations and the number of tubes are key parameters affecting the acoustic performance. For instance, in the 500 Hz octave band (α500), sound absorption of a 30 mm thick hybrid material can reach 0.52 which is 5.7 times higher than the α500 of a typical periodic porous material with the same thickness. Moreover, the broadband sound absorption for mid-frequencies is reasonably high with and α1000 > 0.7. The ratio of first absorption peak wavelength to structure thickness λ/T can reach 17, which is characteristic of deep-subwavelength behaviour.

Originality/value

The concept and experimental validation of a compact hybrid material combining a periodic porous structure such as microchannels and long helical tubes are original. The ability to increase low-frequency sound absorption at constant depth is an asset for applications where volume and weight are constraints.

Details

Rapid Prototyping Journal, vol. 29 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Book part
Publication date: 12 May 2022

Nathan A. Stevenson

The following chapter discusses common approaches to academic interventions and methods for intensifying instruction when previous attempts at instruction have failed…

Abstract

The following chapter discusses common approaches to academic interventions and methods for intensifying instruction when previous attempts at instruction have failed. Contemporary research on intensive intervention is discussed along with competing frameworks for operationalizing intensive intervention to meet the needs of struggling learners.

Details

Delivering Intensive, Individualized Interventions to Children and Youth with Learning and Behavioral Disabilities
Type: Book
ISBN: 978-1-80262-738-1

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Book part
Publication date: 12 August 2014

Susan Albers Mohrman and Abraham B. (Rami) Shani

The chapter redefines the focus of the changes required to create sustainable healthcare away from fixing healthcare organizations and toward reconfiguring the constituent…

Abstract

Purpose

The chapter redefines the focus of the changes required to create sustainable healthcare away from fixing healthcare organizations and toward reconfiguring the constituent elements of the healthcare ecosystem and redefining how they interrelate to yield value more sustainably.

Methodology/approach

Based on a review of recent literature on healthcare reform, we argue that unlike other sectors, healthcare organizations cannot change themselves without changing their connections to the rest of the healthcare ecosystem, including other healthcare organizations, patients, governments, research institutions, vendors, and the citizenry at large. This is because these are not only stakeholders but also integral parts of healthcare processes.

Practical implications

Interventions intended to create more sustainable healthcare must bring together knowledge and perspectives from across the ecosystem, and must converge different sources of information and analysis to generate novel ways of connecting across the ecosystem. Change within a healthcare system cannot achieve the magnitude of transformation needed to become sustainable.

Social implications

If the healthcare ecosystem evolves in the manner described in this chapter, the healthcare ecosystem will no longer center around particular institutions and doctors’ offices but rather be defined by flexible and variable interactions between co-acting elements of the ecosystem.

Originality/value of chapter

The chapter treats the context as the focus of change in order to change the healthcare system. It proposes three kinds of flows: knowledge, clinical, and resource that are already beginning to change and that will eventually result in fundamentally different approaches to healthcare.

Details

Reconfiguring the Ecosystem for Sustainable Healthcare
Type: Book
ISBN: 978-1-78441-035-3

Keywords

Available. Open Access. Open Access
Article
Publication date: 15 March 2022

Mehrshad Mehrpouya, Daniel Tuma, Tom Vaneker, Mohamadreza Afrasiabi, Markus Bambach and Ian Gibson

This study aims to provide a comprehensive overview of the current state of the art in powder bed fusion (PBF) techniques for additive manufacturing of multiple materials. It…

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Abstract

Purpose

This study aims to provide a comprehensive overview of the current state of the art in powder bed fusion (PBF) techniques for additive manufacturing of multiple materials. It reviews the emerging technologies in PBF multimaterial printing and summarizes the latest simulation approaches for modeling them. The topic of “multimaterial PBF techniques” is still very new, undeveloped, and of interest to academia and industry on many levels.

Design/methodology/approach

This is a review paper. The study approach was to carefully search for and investigate notable works and peer-reviewed publications concerning multimaterial three-dimensional printing using PBF techniques. The current methodologies, as well as their advantages and disadvantages, are cross-compared through a systematic review.

Findings

The results show that the development of multimaterial PBF techniques is still in its infancy as many fundamental “research” questions have yet to be addressed before production. Experimentation has many limitations and is costly; therefore, modeling and simulation can be very helpful and is, of course, possible; however, it is heavily dependent on the material data and computational power, so it needs further development in future studies.

Originality/value

This work investigates the multimaterial PBF techniques and discusses the novel printing methods with practical examples. Our literature survey revealed that the number of accounts on the predictive modeling of stresses and optimizing laser scan strategies in multimaterial PBF is low with a (very) limited range of applications. To facilitate future developments in this direction, the key information of the simulation efforts and the state-of-the-art computational models of multimaterial PBF are provided.

Details

Rapid Prototyping Journal, vol. 28 no. 11
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 17 September 2019

Daniel A. Porter, Nicholas Davis, Paul S. Krueger, Adam L. Cohen and David Son

Techniques of extrude and cure additive manufacturing for thermally cured, high viscosity and medical-grade silicone are investigated by using a small ram extruder and a…

554

Abstract

Purpose

Techniques of extrude and cure additive manufacturing for thermally cured, high viscosity and medical-grade silicone are investigated by using a small ram extruder and a near-infrared (IR) laser. The purpose of this study is to evaluate the process parameter effects on the stiffness of the final products.

Design/methodology/approach

Process parameter effects on axial stiffness values and durometer are explored. Parameters such as extrusion layer height, laser speed, laser current, laser raster spacing and multiple laser passes were investigated and compared to traditional cast and cure methods. Dimensional changes were also recorded and compared.

Findings

Tensile and durometer tests show that certain curing parameters give tensile stress and durometers within 10 per cent of bulk material specifications at 200 per cent strain. Parameters that had the highest impact on tensile stress at 200 per cent strain were layer height (0.73 per cent) followed by laser power (0.69 per cent), and then laser raster spacing (0.45 per cent). Parameters that had the highest impact on durometer were laser power (1.00 per cent), followed by layer height, (0.34 per cent) and then laser raster speed (0.32 per cent). Three-dimensional printed samples had about 11.2 per cent more shrinkage than the bulk cast samples in the longest dimension.

Originality/value

This paper is one of the first that demonstrates near IR laser curing parameter effects on three-dimensional printed, commercial off-the-shelf, medical-grade and viscous silicone. The ability to cure very viscous thermosets locally enables interesting technologies such as wire encapsulation, high voltage actuators and drug delivery devices.

Details

Rapid Prototyping Journal, vol. 26 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 21 June 2024

Francesco Bandinelli, Martina Scapin and Lorenzo Peroni

Finite element (FE) analysis can be used for both design and verification of components. In the case of 3D-printed materials, a proper characterization of properties, accounting…

903

Abstract

Purpose

Finite element (FE) analysis can be used for both design and verification of components. In the case of 3D-printed materials, a proper characterization of properties, accounting for anisotropy and raster angles, can help develop efficient material models. This study aims to use compression tests to characterize short carbon-reinforced PA12 made by fused filament fabrication (FFF) and to model its behaviour by the FE method.

Design/methodology/approach

In this work, the authors focus on compression tests, using post-processed specimens to overcome external defects introduced by the FFF process. The material’s elastoplastic mechanical behaviour is modelled by an elastic stiffness matrix, Hill’s anisotropic yield criterion and Voce’s isotropic hardening law, considering the stacking sequence of raster angles. A FE analysis is conducted to reproduce the material’s compressive behaviour through the LS-DYNA software.

Findings

The proposed model can capture stress values at different deformation levels and peculiar aspects of deformed shapes until the onset of damage mechanisms. Deformation and damage mechanisms are strictly correlated to orientation and raster angle.

Originality/value

The paper aims to contribute to the understanding of 3D-printed material’s behaviour through compression tests on bulk 3D-printed material. The methodology proposed, enriched with an anisotropic damage criterion, could be effectively used for design and verification purposes in the field of 3D-printed components through FE analysis.

Details

Rapid Prototyping Journal, vol. 30 no. 11
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 12 October 2018

Sugavaneswaran M. and Arumaikkannu G.

This paper aims to additive manufacture (AM) the multi-material (MM) structure with directional-specific mechanical properties based on the classical lamination theory of…

210

Abstract

Purpose

This paper aims to additive manufacture (AM) the multi-material (MM) structure with directional-specific mechanical properties based on the classical lamination theory of composite materials.

Design/methodology/approach

The polyjet three-dimensional printing (3DP) process is used to fabricate the MM structure with directional-specific mechanical properties. MMs within a layer are positioned and oriented based on the classical lamination theory to achieve directional-specific properties. Mechanical behavior of the AM structure was examined under various loading conditions to justify the directional-specific properties.

Findings

With MM processing capabilities of the polyjet 3DP machine, AM MM structures with directional-specific mechanical properties were fabricated. From experimentation, it was observed that the AM MM structure with a quasi-isotropic laminate has superior tensile and flexural strength, and the AM MM structure with an angle ply laminate has superior shear strength. Various mechanical properties determined through testing will be useful for the selection of an appropriate layup arrangement within a structure for appropriate loading conditions.

Originality/value

This study presents the innovative methodology for the fabrication of AM MM structures with tailor-made mechanical properties. The developed methodology paves way for using the polyjet 3DP MM structure for applications such as the complaint mechanism, snap fits and thin features, which require directional-specific properties.

Details

Rapid Prototyping Journal, vol. 24 no. 7
Type: Research Article
ISSN: 1355-2546

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