Numerical study on the influence of high altitude environment on hydraulic mechanical performance

Biocomposites based on thermoplastic polymers and natural fibers have recently been used in wind turbine blades, to replace non-biodegradable materials. In addition, carbon nanofillers, including carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are being implemented to enhance the mechanical performance of composites. In this work, the Mori–Tanaka approach is used for homogenization of a polymer matrix reinforced by CNT and GNP nanofillers for the first homogenization, and then, for the second homogenization, the effective matrix was used with alfa and E-glass isotropic fibers. The objective is to study the influence of the volume fraction Vf and aspect ratio AR of nanofillers on the elastic properties of the composite. The inclusions are considered in a unidirectional and random orientation by using a computational method by Digimat-MF/FE and analytical approaches by Chamis, Hashin–Rosen and Halpin–Tsai. The results show that CNT- and GNP-reinforced nanocomposites have better performance than those without reinforcement. Additionally, by increasing the volume fraction and aspect ratio of nanofillers, Young’s modulus E increases and Poisson’s ratio ν decreases. In addition, the composites have enhanced mechanical characteristics in the longitudinal orientation for CNT- reinforced polymer and in the transversal orientation for GNP-reinforced polymer.

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Improving the Mechanical Performance of Timber Railway Sleepers with Carbon Fabric Reinforcement: An Experimental and Numerical Study

Journal of Composites for Construction ◽

10.1061/(asce)cc.1943-5614.0001178 ◽

2022 ◽

Vol 26 (1) ◽

Author(s):

Mohammad Siahkouhi ◽

Xinjie Li ◽

Xiaodong Han ◽

Guoqing Jing

Keyword(s):

Mechanical Performance ◽

Numerical Study ◽

Carbon Fabric ◽

Fabric Reinforcement

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A Numerical Study of Railway Ballast Subjected to Direct Shearing Using the Discrete Element Method

Advances in Materials Science and Engineering ◽

10.1155/2020/3404208 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Hongyi Zhao ◽

Jing Chen

Keyword(s):

Discrete Element Method ◽

Mechanical Performance ◽

Numerical Study ◽

Discrete Element ◽

Contact Forces ◽

Angle Of Repose ◽

Particle Rotation ◽

Railway Ballast ◽

Depth Analysis ◽

Element Method

Railway ballast is a coarse granular material used to carry train loads and provide drainage for the rail tracks. This study presents numerical explorations of the mechanical performance of ballast aggregates subjected to direct shear tests. The discrete element method (DEM) was used to investigate the microscopic characteristics of ballast aggregates during shearing while considering contact distribution, particle rotation, and particle displacement. By testing the angle of repose of ballast aggregates, the parameters for the DEM contact model could be calibrated. Four specimens were prepared and then subjected to different normal pressures. The results show that the contact between ballast particles intensifies in terms of the amount and magnitude as the normal pressure increases. A Fourier analysis was applied to investigate the anisotropy of contact normal and the contact forces for ballast aggregates at different shearing phases. The rotational and translational movements of ballast particles were investigated, and this investigation revealed that particle rotation gradually increased as the shearing propagated. Four regions in the aggregates were identified according to the translational pattern of ballast particles. The results of this research provide an in-depth analysis of microscopic characteristics from a particulate scale.

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An experimental and numerical study of the expansion forming of a thick-walled microgroove tube

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes1189 ◽

2008 ◽

Vol 223 (3) ◽

pp. 689-697 ◽

Cited By ~ 3

Author(s):

D Tang ◽

Y Peng ◽

D Li

Keyword(s):

Mechanical Performance ◽

Numerical Study ◽

Surface Profile ◽

Processing Parameters ◽

Forming Process ◽

Axial Section ◽

Die Geometry ◽

Contact Points ◽

Industrial Sectors ◽

Full Contact

CO2 refrigerant-based air conditioning and refrigeration (ACR) is an increasing concern in many industrial sectors for its zero ozone depletion potential. One of the major requirements in its application is the forming technology of thick-walled tube according to the extremely high pressure working conditions of the ACR system. This article presents a study on the expansion process joining the thick-walled microgroove copper tube to aluminium fins. Experiments of the forming process have been carried out. Finite-element models are developed to investigate the deformation of overall and local structures. Evaluation of the joining quality along the longitude axis of the tube is first attempted. The agreement of the results on the contact surface profile confirms that the joint is far away from full contact in the axial section. Formation mechanism of the unexpected contact status lies in displacement of the contact points along the section of the fin collar, which is mainly related to the expanding ratio. To improve the forming quality, discussion on processing parameters and die geometry is conducted. Results show that the expanding ratio is the major factor influencing the thermal—mechanical performance of the joint and 2–6 per cent can be the comprehensively beneficial range for a thick-walled ACR tube; average contact pressure can reach 1.76 Mpa under proper set. The results are helpful for improving the energy efficiency ratio performance of the natural refrigerant-based system.

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An Experimental and Numerical Study of Corona in a Cage with Sandy and Dusty Flow in High Altitude Area

Journal of Electrical Engineering and Technology ◽

10.5370/jeet.2015.10.4.1726 ◽

2015 ◽

Vol 10 (4) ◽

pp. 1726-1733

Author(s):

Yukun Lv ◽

Zekun Ge ◽

Yunpeng Liu ◽

Lei Zhu ◽

Shaoke Wei

Keyword(s):

High Altitude ◽

Numerical Study ◽

High Altitude Area

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A Numerical Study on Mechanical Performance and Hemolysis for Different Types of Centrifugal Blood Pumps

Volume 3: Biomedical and Biotechnology Engineering ◽

10.1115/imece2015-53568 ◽

2015 ◽

Cited By ~ 1

Author(s):

Minwook Chang ◽

Nahmkeon Hur ◽

Mohammad Moshfeghi ◽

Seongwon Kang ◽

Wonjung Kim ◽

...

Keyword(s):

Mechanical Performance ◽

Numerical Study ◽

Type A ◽

Von Mises Stress ◽

Lower Amount ◽

Type D ◽

Cone Type ◽

Blood Pumps ◽

Different Types ◽

Impeller Type

Centrifugal blood pumps have to be considered from both mechanical and biomechanical aspects. While, evaluations of mechanical factors, such as performance curve, are straightforward, biomechanical parameters, such as hemolysis indices, are still indistinct. Hence, different mathematical models and computational methods have been employed for the evaluation of hemolysis indices. This article aims to investigate four different types of centrifugal blood pumps from both mechanical and biomechanical aspects. The pumps are cone-type impeller (Type-A), channel-type impeller with shroud (Type-B), open impeller without shroud (Type-C) and shrouded impeller-type (Type-D). The CFD simulations are conducted using standard k-ε turbulence model in multiple reference frame (MRF) method. Various values for rotational speed and flow rate are studied. The streamlines clearly show the effects of impeller geometry on flow patterns. It is also demonstrated that in all of the models, the areas of the recirculation have high value of von Mises stress. In addition, the effect of the volute in the Type-D on the pressure distribution and streamline smoothness is clearly observed. In another part, the modified index of hemolysis (MIH) calculated based on Eulerian approach is investigated for three predefined conditions of extracorporeal membrane oxygenation (ECMO), ventricular assist device (VAD), and full-load. The results reveal that the Type-A and Type-D have the highest and lowest MIH values, respectively in all of the predefined conditions. In addition, all of the pumps generate lower amount of hemolysis when they are operated in VAD condition.

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Numerical Simulation of Aluminum Honeycomb Subjected to Combined Compression-Shear Loads

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.846.211 ◽

2016 ◽

Vol 846 ◽

pp. 211-216

Author(s):

Asm Ayman Ashab ◽

Dong Ruan ◽

Guo Xing Lu

Keyword(s):

Cell Walls ◽

Mechanical Performance ◽

Numerical Study ◽

Fe Analysis ◽

Fe Model ◽

Plateau Stress ◽

Shear Loads ◽

Aluminum Honeycomb ◽

Previous Experimental Study ◽

Good Agreement

A full scale finite element (FE) analysis has been conducted on aluminum hexagonal honeycomb to investigate its deformation mechanism and mechanical performance under combined compression-shear loads. ANSYS LS/DYNA software has been employed in this numerical study. The honeycomb FE model has the same dimensions (cell size and cell wall thickness) as those used in the previous experimental study. The FE model has been verified by the experimental results. A good agreement between the experimental and numerical results has been reached. This numerical analysis facilitates the measurement of the vertical and horizontal forces applied to honeycomb specimens. The effects of strain rate, plane orientation of cell walls and loading angle on the plateau stress and energy absorption of honeycomb specimens under combined compression-shear loads were investigated.

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Numerical Study on the Static Response of Grouting-Sleeve Reinforcement-Connection Component with Different Sleeve-Rib Space

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.578-579.882 ◽

2014 ◽

Vol 578-579 ◽

pp. 882-885

Author(s):

Fan Gu ◽

Peng Zhang ◽

Wei Jian Zhao ◽

Duo Zhang

Keyword(s):

Mechanical Performance ◽

Numerical Study ◽

Internal Force ◽

Finite Element Models ◽

Stress Distributions ◽

Static Response ◽

Actual Structure ◽

Axial Tension ◽

Grouting Material ◽

Connection Component

According to the actual structure, the ABAQUS finite element models of grouting-sleeve reinforcement-connection component with different sleeve-rib space were established, and the mechanical performance of component under the action of axial tension load was studied. Meanwhile, the stress distributions among sleeve with six kinds of sleeve-rib space by means of stress nephogram were obtained. Numerical simulation result shows that with the sleeve-rib space decreasing from 56mm to 8mm, the constraint capability of grouting material on reinforcement is better and better, and the internal force distribution in sleeve tends to be more homogeneous.

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