Targeted sound attenuation capacity of 3D printed noise cancelling waveguides

Arjunan, Arun

doi:10.1016/j.apacoust.2019.03.008

Cited by 36 publications

(13 citation statements)

References 40 publications

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“…Using these techniques material particles ranging from 10-150 μm are used for printing structures allowing the possibility of highresolution porous solids [11,12]. Considering, this advantage, SLM is suited for the fabrication of highly complex porous designs [13,14]. Accordingly, this study focuses on the development of porous structures using SLM, attempting to mimic the permeability and mechanical properties of a damaged tibia using Ti6Al4V cellular structures [15,16].…”

Section: Introductionmentioning

confidence: 99%

Mechanical performance of highly permeable laser melted Ti6Al4V bone scaffolds

Arjunan

Demetriou

Baroutaji

et al. 2020

Journal of the Mechanical Behavior of Biomedical Materials

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122

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Critically engineered stiffness and strength of a scaffold are crucial for managing maladapted stress concentration and reducing stress shielding. At the same time, suitable porosity and permeability are key to facilitate biological activities associated with bone growth and nutrient delivery. A systematic balance of all these parameters are required for the development of an effective bone scaffold. Traditionally, the approach has been to study each of these parameters in isolation without considering their interdependence to achieve specific properties at a certain porosity. The purpose of this study is to undertake a holistic investigation considering the stiffness, strength, permeability, and stress concentration of six scaffold architectures featuring a 68.46-90.98% porosity. With an initial target of a tibial host segment, the permeability was characterised using Computational Fluid Dynamics (CFD) in conjunction with Darcy's law. Following this, Ashby's criterion, experimental tests, and Finite Element Method (FEM) were employed to study the mechanical behaviour and their interdependencies under uniaxial compression. The FE model was validated and further extended to study the influence of stress concentration on both the stiffness and strength of the scaffolds. The results showed that the pore shape can influence permeability, stiffness, strength, and the stress concentration factor of Ti6Al4V bone scaffolds. Furthermore, the numerical results demonstrate the effect to which structural performance of highly porous scaffolds deviate, as a result of the Selective Laser Melting (SLM) process. In addition, the study demonstrates that stiffness and strength of bone scaffold at a targeted porosity is linked to the pore shape and the associated stress concentration allowing to exploit the design freedom associated with SLM.

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Section: Introductionmentioning

confidence: 99%

Mechanical performance of highly permeable laser melted Ti6Al4V bone scaffolds

Arjunan

Demetriou

Baroutaji

et al. 2020

Journal of the Mechanical Behavior of Biomedical Materials

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122

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“…At this time, the transmitted and received pulse signal are coupled at the receiver [11], therefore, the received pulse signal is affected by the transmitted signal. Various wave cancellation methods have been discussed, such as acoustic cancellation [12,13] and radar echo cancellation [14]. However, as the transmitted and received pulse signals are relevant, they are difficult to be separated by the echo cancellation.…”

Section: Introductionmentioning

confidence: 99%

Micro-Motion Feature Extraction of a Rotating Target Based on Interrupted Transmitting and Receiving Pulse Signal in an Anechoic Chamber

Zhao

Liu

et al. 2019

Electronics

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The pulse signal is widely used in micro-motion feature extraction of rapidly rotating targets as its pulse repetition frequency (PRF) can be high. However, when the pulse signal is implemented in a range-limited anechoic chamber for micro-motion feature extraction, the transmitted and reflected pulse signals may be coupled at the receiver. To solve this problem, the interrupted transmitting and receiving (ITR) method is applied to transmit the pulse signal with hundreds of sub-pulses. The target echo can be received when the sub-pulse is not transmitted. Hence, it avoids the coupling effect of transmitted signals and echoes. Then, the whole process of micro-motion feature extraction for rotating target is proposed based on the ITR method. At last, the simulations and experiments verify that the rotating target micro-Doppler can be extracted by the ITR pulse signal.

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“…Quantification of the coating porosity was carried out through optical microscopy investigation of the sample cross-section. A total of ten sliced sections were investigated and the cross-sectional data of each tile was analysed using ImageJ [55][56][57]. The average measurement is then reported as the single number porosity of the coating.…”

Section: Coating Characterisationmentioning

confidence: 99%

Effect of nano-Al₂O₃ addition on the microstructure and erosion wear of HVOF sprayed NiCrSiB coatings

Praveen

Arjunan

2019

Mater. Res. Express

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Development of nanostructured high velocity oxy-fuel (HVOF) coatings with low porosity, high strength and increased wear resistance is still in its infancy. Combining nanoparticles with conventional microscale powders are increasingly being investigated to use with feedstock materials for thermal spray processes. Accordingly, this work investigates the addition of nano-Al 2 O 3 particles on the microstructure and erosion wear of NiCrSiB HVOF coating in a stainless steel (AISI 304) substrate. Particle analysis of the NiCrSiB feedstock was conducted and the maximum allowable addition of Al 2 O 3 nanoparticles have been identified using the 'mass mixture ratio' model considering both the particle size and density. Consequently, two cases are considered and their performance analysed: a maximum allowable case of 1.4 wt%, followed by a 0.17 wt% addition of nano-Al 2 O 3 with NiCrSiB. Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and x-ray Diffraction (XRD) analysis were employed to inform the microstructure, material composition and phase spectrum of the resulting coatings. Subsequently, the nanostructured coating was exposed to both a pull-off adhesion strength test and hot air jet (450°C) hard particle erosion to characterise its performance. It was found that the microhardness of the HVOF NiCrSiB coating improved from 576 HV 0.3 to 748 HV 0.3 with the addition of 1.4 wt% nano-Al 2 O 3 . Furthermore, the nanostructured coating also exhibited high erosion resistance at a 90°erodent impact angle. The increase in erosion wear resistance was due to the increase in the hardness as a result of the nano-Al 2 O 3 addition. IntroductionSolid particle erosion wear plays an important role in the material degradation process of engineering components [1-3], including turbines, thermal power plants, pipelines, hydropower machinery and combustion systems [4,5]. According to Martinella [6], one of the major industries affected by solid particle erosion are coal based electric power plants. This is caused as a result of the fly ash interaction with the wall surfaces facilitated by the high-temperature flue gases. The prolonged effect of this causes the boiler components to fail and currently account for ∼25% of the down time [7]. The subsequent cost effect of erosion wear damage in such cases is often as high as 54% of the overall maintenance cost [8,9]. Consequently, coatings that can improve the surface resistance to solid particle erosion wear along with high-temperature oxidation protection systems are increasingly being sought.Among the numerous solution available to prevent or control the fly ash erosion, surface coatings [10] are the most widely adopted technique [11][12][13]. When it comes to coating methodology, several techniques are available including vapour deposition [14], electrochemical, sol-gel [14] and thermal spraying [14]. Among these different coating techniques, thermal spray techniques [15,16] have received increased attention largely due to their capacity to accommodate a range of ...

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Targeted sound attenuation capacity of 3D printed noise cancelling waveguides

Cited by 36 publications

References 40 publications

Mechanical performance of highly permeable laser melted Ti6Al4V bone scaffolds

Mechanical performance of highly permeable laser melted Ti6Al4V bone scaffolds

Micro-Motion Feature Extraction of a Rotating Target Based on Interrupted Transmitting and Receiving Pulse Signal in an Anechoic Chamber

Effect of nano-Al₂O₃ addition on the microstructure and erosion wear of HVOF sprayed NiCrSiB coatings

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Targeted sound attenuation capacity of 3D printed noise cancelling waveguides

Cited by 36 publications

References 40 publications

Mechanical performance of highly permeable laser melted Ti6Al4V bone scaffolds

Mechanical performance of highly permeable laser melted Ti6Al4V bone scaffolds

Micro-Motion Feature Extraction of a Rotating Target Based on Interrupted Transmitting and Receiving Pulse Signal in an Anechoic Chamber

Effect of nano-Al2O3 addition on the microstructure and erosion wear of HVOF sprayed NiCrSiB coatings

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Effect of nano-Al₂O₃ addition on the microstructure and erosion wear of HVOF sprayed NiCrSiB coatings