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Article
Publication date: 24 February 2022

Sivasankar Arumugam and Rajesh Ranganathan

This research aims to focus on developing a customized support surface using additive manufacturing (AM) for effective pressure relief for patients who are in bed or wheelchair…

Abstract

Purpose

This research aims to focus on developing a customized support surface using additive manufacturing (AM) for effective pressure relief for patients who are in bed or wheelchair suffering from pressure ulcers (PU).

Design/methodology/approach

A novel customized support surface is developed using AM technology incorporated with magnetic levitation and ball and socket mechanisms. Magnetic levitation provides cushioning effect for the developed cushion to users who are sitting in a wheelchair and increases the rate of healing. The ball and socket mechanism provides the user body's self-adaptive mechanism and reduces shear and friction forces between the surfaces of the additive manufactured cushion and the human buttocks.

Findings

From the results of ISO 16480-6 biomechanical standardized tests, the additive manufactured support surface performed better than, or on par with, the most widely available commercial cushions. It is evident that the developed cushion’s peak pressure values are lower when compared with other cushions. The overall efficiency of the developed cushion was qualitatively reported; 67% of people felt it was excellent and 22% of people responded as good and 11% were satisfactory. Henceforth, the overall effectiveness of the developed support surface provides a better experience to the end-user in the view of PU reduction.

Originality/value

A developed additive manufactured customized support surface will be an alternative approach for the reduction of PU, and it overcomes the drawbacks faced by the currently available cushions.

Details

Rapid Prototyping Journal, vol. 28 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 16 August 2021

Tugba Inan Gunaydin

This paper presents the numerical examination of wind pressure distributions on U-plan shaped buildings having four different depth ratios (DR) as 0.5, 1, 2 and 4 over wind…

Abstract

Purpose

This paper presents the numerical examination of wind pressure distributions on U-plan shaped buildings having four different depth ratios (DR) as 0.5, 1, 2 and 4 over wind incidence angle (WIA) of 0°. The purpose of this study is to investigate the effect of irregular building form, DRs, distances from the reentrant corner, wind velocity values on and around wind pressure distributions of the buildings. With this aim, ANSYS Fluent 20.0 Computational Fluid Dynamics (CFD) program is used for the analysis.

Design/methodology/approach

Four U-shaped buildings having the same height, width and wing length but having different DR in plan were analyzed by the application of CFD package of ANSYS 20. With this purpose, wind pressure distributions on and around U-plan shaped buildings were analyzed for the wind velocity values of 2 and 5 m/s over WIA of 0°. Comprehensive results were obtained from the analyses.

Findings

While the change in the DR values did not create a significant change in positive pressure coefficients on A and E surfaces, negative pressure values increased as the DR decreased. The negative pressure coefficients observed on the A and E surfaces become higher than the positive pressure coefficients with the decrease in the DR. On contrary to that condition, with the decrease in the DR, G surfaces take higher positive pressure coefficients than the negative pressure coefficients. The reason for this is that the DR decreases and negative pressure values on G surface significantly decrease. The effect of the DR on the pressure coefficients is remarkable on B and D surfaces. The negative pressure coefficients on the B and D surfaces tend to increase as the DR decreases.

Research limitations/implications

This study focused on DRs and wind velocity values effect on pressure coefficients to limit variables. Different building wing dimensions did not take into account.

Originality/value

Although there are a number of studies related to wind behavior of irregular plan shaped buildings, irregular building forms have not been extensively investigated parametrically, especially in terms of the effect of DR on wind pressures. This study is therefore designed to fill this gap by analyzing impacts of various parameters like building shape with various DRs, WIA and wind velocity values on wind pressure distributions and velocity distributions on and around the building.

Details

Journal of Engineering, Design and Technology , vol. 20 no. 3
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 15 June 2015

Zhenyuan Tang and Decheng Wan

The jet impingement usually accompanying large interface movement is studied by the in-house solver MLParticle-SJTU based on the modified moving particle semi-implicit (MPS…

Abstract

Purpose

The jet impingement usually accompanying large interface movement is studied by the in-house solver MLParticle-SJTU based on the modified moving particle semi-implicit (MPS) method, which can provide more accurate pressure fields and deformed interface shape. The comparisons of the pressure distribution and the shape of free surface between the presented numerical results and the analytical solution are investigated. The paper aims to discuss these issues.

Design/methodology/approach

To avoid the instability in traditional MPS, a modified MPS method is employed, which include mixed source term for Poisson pressure equation (PPE), kernel function without singularity, momentum conservative gradient model and highly precise free surface detection approach. Detailed analysis on improved schemes in the modified MPS is carried out. In particular, three kinds of source term in PPE are considered, including: particle number density (PND) method, mixed source term method and divergence-free method. Two typical kernel functions containing original kernel function with singularity and modified kernel function without singularity are analyzed. Three kinds of pressure gradient are considered: original pressure gradient (OPG), conservative pressure gradient (CPG) and modified pressure gradient (MPG). In addition, particle convergence is performed by running the simulation with various spatial resolutions. Finally, the comparison of the pressure fields by the modified MPS and by SPH is presented.

Findings

The modified MPS method can provide a reliable pressure distribution and the shape of the free surface compared to the analytical solution in a steady state after the water jet impinging on the wall. Specifically, mixed source term in PPE can give a reasonable profile of the shape of free surface and pressure distribution, while PND method adopted in the traditional MPS is not stable in simulation, and divergence-free method cannot produce rational pressure field near the wall. Two kernel functions show similar pressure field, however, the kernel function without singularity is preferred in this case to predict the profile of free surface and pressure on the wall. The shape of free surface by CPG and MPG is agreement with the analytical solution, while a great discrepancy can be observed by OPG. The pressure peak by MPG is closer to the analytical solution than that by CPG, while the pressure distribution on the right hand side of the pressure peak by latter is better match with the analytical solution than that by former. Besides, fine spatial resolution is necessary to achieve a good agreement with analytical results. In addition, the pressure field by the modified MPS is also quite similar to that by SPH, and this can further validate the reliable of current modified MPS.

Originality/value

The present modified MPS appears to be a stable and reliable tool to deal with the impinging jet flow problems involving large interface movement. Mixed source term in PPE is superior to PND adopted in the traditional MPS and divergence-free method. The kernel function without singularity is preferred to improve the computational accuracy in this case. CPG is a good choice to obtain the shape of free surface and the pressure distribution by jet impingement.

Details

Engineering Computations, vol. 32 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 8 April 2014

Jun Sun, Xinlong Zhu, Liang Zhang, Xianyi Wang, Chunmei Wang, Hu Wang and Xiaoyong Zhao

Current lubrication analyses of misaligned journal bearings were generally performed under some given preconditions. To make the lubrication analysis closer to the actual…

Abstract

Purpose

Current lubrication analyses of misaligned journal bearings were generally performed under some given preconditions. To make the lubrication analysis closer to the actual situation and usable to the journal bearing design, the purpose of this paper was to calculate the lubrication characteristics of misaligned journal bearings considering the viscosity-pressure effect of the oil, the surface roughness and the elastic deformation of the journal bearing at the same time.

Design/methodology/approach

The lubrication of bearings was analyzed using the average Reynolds equation. The deformation of the bearing surface under oil film pressure was calculated by a compliance matrix method. The compliance matrix was established by finite element analysis of the bearing housing. The viscosity-pressure and viscosity–temperature equations were used in the analysis.

Findings

The oil viscosity-pressure relationship has a significant effect on the lubrication of misaligned journal bearings. The surface roughness will affect the lubrication of misaligned journal bearings when the eccentricity ratio and angle of journal misalignment are all large. The directional parameter of the surface has an obvious effect on the lubrication of misaligned journal bearings. The deformation of the bearing surface has a remarkable effect on the lubrication of misaligned journal bearings.

Originality/value

The lubrication characteristics of misaligned journal bearings were calculated considering the viscosity-pressure effect of the oil, the surface roughness and the elastic deformation of the journal bearing at the same time. The results of this paper are helpful to the design of the bearing.

Details

Industrial Lubrication and Tribology, vol. 66 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 20 November 2020

S. Madhu and M. Balasubramanian

The purpose of this study is for solving many issues in production that includes processing of complex-shaped profile, machining of high-strength materials, good surface finish…

Abstract

Purpose

The purpose of this study is for solving many issues in production that includes processing of complex-shaped profile, machining of high-strength materials, good surface finish with high-level precision and minimization of waste. Among the various advanced machining processes, abrasive jet machining (AJM) is one of the non-traditional machining techniques used for various applications such as polishing, deburring and hole making. Hence, an overview of the investigations done on carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GRFP) composites becomes important.

Design/methodology/approach

Discussion on various approaches to AJM, the effect of process parameters on the glass fiber and carbon fiber polymeric composites are presented. Kerf characteristics, surface roughness and various nozzle design were also discussed.

Findings

It was observed that abrasive jet pressure, stand-off distance, traverse rate, abrasive size, nozzle diameter, angle of attack are the significant process parameters which affect the machining time, material removal rate, top kerf, bottom kerf and kerf angle. When the particle size is maximum, the increased kinetic energy of the particle improves the penetration depth on the CFRP surface. As the abrasive jet pressure is increased, the cutting process is enabled without severe jet deflection which in turn minimizes the waviness pattern, resulting in a decrease of the surface roughness.

Research limitations/implications

The review is limited to glass fiber and carbon fiber polymeric composites.

Practical implications

In many applications, the use of composite has gained wide acceptance. Hence, machining of the composite need for the study also has gained wide acceptance.

Social implications

The usage of composites reduces the usage of very costly materials of high density. The cost of the material also comes down.

Originality/value

This paper is a comprehensive review of machining composite with abrasive jet. The paper covers in detail about machining of only GFRP and CFRP composites with various nozzle designs, unlike many studies which has focused widely on general AJM of various materials.

Details

World Journal of Engineering, vol. 18 no. 2
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 13 April 2015

Qiyin Lin, Zhengying Wei, Ning Wang and Wei Chen

The purpose of this paper is to study the influence of large-area texture/slip surface, especially the area and position of large-area texture surface on journal bearing, and…

1624

Abstract

Purpose

The purpose of this paper is to study the influence of large-area texture/slip surface, especially the area and position of large-area texture surface on journal bearing, and improve the tribological performances of journal bearing.

Design/methodology/approach

A modified texture/slip numerical boundary condition with double parameters is presented and is applied onto the region where surface textures locate to represent the impact of actual texture/slip surface. A phase change condition is used to analyze cavitation phenomena.

Findings

The global/cumulative texture effect can be represented by applying texture/slip condition onto the region where it locates. The area and position of texture/slip surface would significantly affect the cavitation and load-carrying capacity. Texture/slip surface would not affect the pressure and load-carrying capacity when it locates at cavitation zone. The effect of texture/slip surface on load-carrying capacity would be beneficial if it locates at the pressure rise region, but its effect would be adverse if it locates at the pressure drop region. Well-designed texture/slip surface can improve tribological performances.

Originality/value

The developed texture/slip boundary condition can be a suitable and useful tool to analyze the effect of large-area texture/slip surface and especially to optimize the area and position of large-area texture surface. This approach can be complementary to conventional approach which is used to analyze the influence of textures’ real configurations and parameters.

Details

Industrial Lubrication and Tribology, vol. 67 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 9 April 2019

Haniff Abdul Rahman, Jaharah A. Ghani, Wan Mohd Faizal Wan Mahmood and Mohammad Rasidi Mohammad Rasani

This study aims to simulate the influence of surface texturing produced via turning process toward pressure distribution and load capacity generation using computational fluid…

Abstract

Purpose

This study aims to simulate the influence of surface texturing produced via turning process toward pressure distribution and load capacity generation using computational fluid dynamics (CFD).

Design/methodology/approach

The dimple geometry was obtained via turning process, to be used for future application on piston skirt surfaces. Two cases were studied: a preliminary study using single periodic dimple assuming linear dimple distribution and an application study using multiple periodic dimples to address actual dimple orientation following the turning process.

Findings

For the first case, the dimple was proven to generate load capacity with regard to untextured surface, owing to the asymmetric pressure distribution. Increasing the Reynolds number, dimple width and dimple depth was found to increase load capacity. For the second case, although load capacity increases via surface texturing, the value was 97.4 per cent lower relative to the first case. This confirmed the importance of doing multiple dimple simulations for real applications to achieve more realistic and accurate results.

Originality/value

A new concept of dimple fabrication using a low-cost turning process has been developed, with a potential to increase the tribological performance under hydrodynamic lubrication. Previous CFD simulations to simulate these benefits have been done using a single periodic dimple, assuming equal distribution array between dimples. However, due to the different orientations present for dimples produced using turning process, a single periodic dimple simulation may not be accurate, and instead, multiple dimple simulation is required. Therefore, present research was conducted to compare the results between these two cases and to ensure the accuracy of CFD simulation for this type of dimple.

Details

Industrial Lubrication and Tribology, vol. 71 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 10 June 2021

Chunxiao Jiao, Jianghai Xu, Donglin Zou, Na Ta and Zhushi Rao

The purpose of this paper is to study the flow field characteristics of the micro-scale textured bearing surfaces using the lattice Boltzmann method based on the microscopic…

Abstract

Purpose

The purpose of this paper is to study the flow field characteristics of the micro-scale textured bearing surfaces using the lattice Boltzmann method based on the microscopic dynamics of the fluid.

Design/methodology/approach

Considering the inertia effects and the micro-scale effects, the models of a single micro-scale texture unit cell with different shapes and different film thickness ratios are established. The influence of pressure difference between inlet and outlet of the unit cell on flow characteristics is studied.

Findings

The surface pressure distribution, flow patterns and pressure contours in the flow field are obtained. The results reveal that the pressure difference has a significant influence on the characteristics of the micro-textured flow field.

Originality/value

The results have certain guiding significance for further step investigation on microscopic lubrication mechanism of the water-lubricated polymer bearings.

Details

Industrial Lubrication and Tribology, vol. 73 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 16 August 2011

Sudipto Ray and S.K. Roy Chowdhury

The paper's aim is to predict numerically the contact temperatures between two rough sliding bodies and to compare with the experimental results.

Abstract

Purpose

The paper's aim is to predict numerically the contact temperatures between two rough sliding bodies and to compare with the experimental results.

Design/methodology/approach

An elastic contact algorithm is used to analyze the normal contact between two nominally smooth surfaces. The algorithm evaluates real contact area using digitized roughness data and the corresponding contact pressure distribution. Using finite element method a steady state 3D temperature distribution at the interface between the sliding bodies is obtained. Using infrared (IR) imaging technique, experiments were carried out to measure the contact temperature distribution between rough rubbing bodies with a systematic variation of surface roughness and operating variables.

Findings

Contact temperature distributions over a wide range of normal load, sliding velocity and surface roughness have been obtained. It was seen that the maximum contact temperature expectedly increases with surface roughness (Sa values), normal load and sliding velocity. The results also indicate that the “hot spots” are located exactly at the positions where the contact pressures are extremely high. Temperatures can be seen to fall drastically at areas where no asperity contacts were established. The temperature contours at different depths were also plotted and it was observed that the temperatures fall away from the actual contact zone and relatively high temperatures persist at the “hot spot” zones much below the contact surface. Finally it is encouraging to find a good correlation between the numerical and experimental results and this indicates the strength of the present analysis.

Research limitations/implications

Experimental accuracy can be improved by using a thermal imaging camera that measures emissivity in situ and uses it to find the contact temperature. The spatial resolution and the response time of the camera also need to be improved. This can improve the correlation between numerical and experimental results.

Practical implications

One of the major factors attributed to the failure of sliding components is the frictional heating and the resulting flash temperatures at the sliding interface. However, it is not easy to measure such temperatures owing to the inherent difficulties in accessing the contact zone. Besides, thermal imaging techniques can be applied only with such tribo‐pairs where at least one of the contacting materials is transparent to IR radiation. In practice, such cases are a rarity. However, the good correlation observed between the numerical and experimental results in this work would give the practicing engineer a confidence to apply the numerical model directly and calculate contact temperatures for any tribo‐material pairs that are generally seen around.

Originality/value

A good correlation between the numerical and experimental results gives credence to the fact that the numerical model can be used to predict contact temperatures between any sliding tribo‐pairs.

Details

Industrial Lubrication and Tribology, vol. 63 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 May 1994

M.M. De Guzman, C.A.J. Fletcher and J.D. Hooper

The detailed flow behaviour around a four—hole Cobra Pitot pressureprobe, developed by the Commonwealth Scientific and Industrial ResearchOrganization, Australia, (CSIRO), to…

Abstract

The detailed flow behaviour around a four—hole Cobra Pitot pressure probe, developed by the Commonwealth Scientific and Industrial Research Organization, Australia, (CSIRO), to determine the pressure and the velocity components in three dimensional single‐phase/multi‐phase fluid flow, is investigated computationally. The incompressible steady state Navier—Stokes equations are solved numerically using a general purpose computational fluid dynamics (CFD) code developed at CANCES. Computational results are presented for representative probe pitch and yaw angles at a Reynolds number = 2 × 103, emphasising the pressure distribution and flow separation patterns on the probe tip adjacent to the pressure ports. Quantitative comparison of the computational simulation to experimental results is done by comparing experimental calibration data to numerically computed pressure responses. The topological features of the near tip flow behaviour are visualised using critical point concepts and three dimensional streamlines. Additional qualitative comparison to experiment is discussed using data from a preliminary experimental investigation using surface oil film visualisation techniques, where available. Conclusions are drawn concerning the near tip flow behaviour, the good level of agreement between the numerical results and experimental data and the effectiveness of using a computational analysis to provide accurate detail useful for engineering design purposes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 4 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

1 – 10 of over 33000