Computation of magnetic field in an actuator

Design and optimization of an actuators based on magnetostrictive technology requires computation of the magnetic field. The “MS”-technology offers an attractive controllability with high power density. The magnetostriction is a reversible feature which can be used in various actuator layouts. The actuator performance depends on driving magnetic field and the particular magnetic properties of used materials. Good understanding of specific design constrains is required to define and to optimized a magnetostrictive actuator. The non-linear computation of the magnetic field using FEM software is vital for the finale experimental design of a low-frequency actuator. This paper presents results of magnetic field simulation with FEMM software package and experimental measurements of the magnetic flux density. Good correlation between the simulation results and experimental measurements has been achieved

Effect of process parameters and optimization of CO2 laser cutting of ultra high performance polyethylene

The aim of this work is to relate the cutting edge quality parameters (responses) namely: upper kerf, lower kerf, ratio of the upper kerf to lower kerf and cut edge roughness to the process parameters considered in this research and to find out the optimal cutting conditions. The process factors implemented in this research are: laser power, cutting speed and focal point position. Design of experiment (DoE) was used by implementing Box-Behnken design to achieve better cut qualities within existing resources. Mathematical models were developed to establish the relationship between the process parameters and the edge quality parameters. Also, the effects of process parameters on each response were determine. Then, a numerical optimization was performed to find out the optimal process setting at which the quality features are at their desired values. The effect of each factor on the responses was established and the optimal cutting conditions were found

Design and application of magneto-rheological fluid

Magneto-Rheological Fluid (MRF) technology is an old “newcomers” coming to the market at high speed. Various industries including the automotive industry are full of potential MRF applications. Magneto-Rheological Fluid technology has been successfully employed already in various low and high volume applications. A structure based on MRF might be the next generation in design for products where power density, accuracy and dynamic performance are the key features. Additionally, for products where is a need to control fluid motion by varying the viscosity, a structure based on MRF might be an improvement in functionality and costs. Two aspects of this technology, direct shear mode (used in brakes and clutches) and valve mode (used in dampers) have been studied thoroughly and several applications are already present on the market. Excellent features like fast response, simple interface between electrical power input and mechanical power output, and precise controllability make MRF technology attractive for many applications. This paper presents the state of the art of an actuator with a control arrangement based on MRF technology. The study shows that excellent features like fast response, simple interface between electrical power input and the mechanical power output, and controllability make MRF the next technology of choice for many applications

Design of magneto-rheological (MR) valve

Magneto-Rheological Fluid (“MRF”) technology has been successfully employed in various low and high volume automotive applications. Good understanding of specific design constraints is required to define and to optimize a magneto-rheological device. This article presents parametrical analyses with magnetic simulations, of a magneto-rheological valve and a magneto-rheological orifice. Experimental rig assemblies of two different control devices have been designed, built and the performances have been evaluated experimentally. Controlled pressure drops, of 0.6MPa @ 4.5A at 5cm³/s in the orifice mode, and 1.5MPa @ 4.5A at 0 cm³/s, in the valve mode, using MRF132-AD, have been achieved. The study shows that excellent features like the fast response and the contactless nature of MRF control are attractive for various control devices

Design of a magnetostrictive (MS) actuator

Several advanced technologies are introduced in automotive applications. Higher energy density and dynamic performance are demanding new and cost effective actuator structures. Magnetostriction (MS), change in shape of materials under the influence of an external magnetic field, is one of these advanced technologies. Good understanding of specific design constrains is required to define and optimized a magnetostrictive actuator. This paper presents parametrical analysis with magnetic simulation of a magnetostrictive actuator. Proposed actuator has been designed, and the performance has been evaluated on experimental rig. Strain, elongation of the shaft, of 1000ppm at 10Amp and a blocked force over 4500N has been achieved with shaft of 8mm diameter, made of Terfenol-D. Furthermore, the effect of pre-stress of the Terfenol-D shaft has been evaluated experimentally. The study shows that excellent features can be obtained by magnetostrictive materials for many advanced applications

Using Taguchi method to optimize welding pool of dissimilar laser welded components

In the present work CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and AISI 1009 low carbon steel plates. Laser power, welding speed, and defocusing distance combinations were carefully selected with the objective of producing welded joint with complete penetration, minimum fusion zone size and acceptable welding profile. Fusion zone area and shape of dissimilar austenitic stainless steel with ferritic low carbon steel were evaluated as a function of the selected laser welding parameters. Taguchi approach was used as statistical design of experiment (DOE) technique for optimizing the selected welding parameters in terms of minimizing the fusion zone. Mathematical models were developed to describe the influence of the selected parameters on the fusion zone area and shape, to predict its value within the limits of the variables being studied. The result indicates that the developed models can predict the responses satisfactorily

Application of open pore cellular foam for air breathing PEM fuel cell

This is an accepted manuscript of an article published by Elsevier in International Journal of Hydrogen Energy on 07/06/2017, available online: https://doi.org/10.1016/j.ijhydene.2017.05.114 The accepted version of the publication may differ from the final published version.Open Pore Cellular Foam (OPCF) has received increased attention for use in Proton Exchange Membrane (PEM) fuel cells as a flow plate due to some advantages offered by the material, including better gas flow, lower pressure drop and low electrical resistance. In the present study, a novel design for an air-breathing PEM (ABPEM) fuel cell, which allows air convection from the surrounding atmosphere, using OPCF as a flow distributor has been developed. The developed fuel cell has been compared with one that uses a normal serpentine flow plate, demonstrating better performance. A comparative analysis of the performance of an ABPEM and pressurised air PEM (PAPEM) fuel cell is conducted and poor water management behaviour was observed for the ABPEM design. Thereafter, a PTFE coating has been applied to the OPCF with contact angle and electrochemical polarisation tests conducted to assess the capability of the coating to enhance the hydrophobicity and corrosion protection of metallic OPCF in the PEM fuel cell environment. The results showed that the ABPEM fuel cell with PTFE coated OPCF had a better performance than that with uncoated OPCF. Finally, OPCF was employed to build an ABPEM fuel cell stack where the performance, advantages and limitations of this stack are discussed in this paper

Pretreatment techniques used in biogas production from grass

Grass is being considered as a potential feedstock for biogas production, due to its low water consumption compared to other crops, and the fact that it can be cultivated in non-arable lands, avoiding the direct competition with food crops. However, biogas production is limited by the characteristics of the feedstock; in particular its complex lignocellulosic structure. Hence, different pretreatment methods are being investigated for grass structure disruption before undergoing the anaerobic digestion process. The aim of this paper is to review current knowledge on pretreatment techniques used for grassland biomass. Pretreatment techniques were categorized into mechanical, microwave, thermal, chemical and biological groups. The effect of the application of each studied methods on the biogas yield and on the energy balance is discussed. A further comparison between the covered techniques was revealed

Renewable energy scenario and environmental aspects of soil emission measurements

European Commission has set clear targets for 2020 regarding energy and environment policy; these targets include 20% cut in greenhouse gas emissions against the 1990 levels. It is believed that adopted strategy has encouraged the renewable energy applications during the last two decades. Moreover, measurement deviations of carbon dioxide flux occurring in respiration chambers has been seen of a great importance to explain the biochemical parameters affecting the climate change issue. This is attributed on many occasions to chamber design constraints and the way they are coupled with the studied site location. This is illustrated by external disturbances whereby when they happen while gas measurements are taken measurement deviations become more evident. This paper surveys the different soil physical, biological and geotechnical parameters and links them to meteorological ones. Consequently it explores their direct and indirect effects to the produced soil efflux. Furthermore this paper proposes several soil temperature models according to the studied case constraints to see what affects soil efflux production. Moreover a clear understanding of what affects the measurement process was achieved through surveying all the internal and external pressure parameters and how they influence the chamber in relation to time. The conclusion is that respiration chamber designers need to preserve chamber internal temperature and pressure to be equal to the outer atmosphere for the case of stabile external conditions. For the case of unstable external conditions design counter measures are incorporated. Furthermore the appropriate gas sensor needs to be selected professionally with emphasis on the importance of installation location inside the chamber. Likewise soil bacterial type and soil temperature also has an influence on efflux production

Prediction of the gas emission from porous media with the concern of energy and environment

Measuring soil carbon dioxide efflux is a challenging task even when it is performed using respiration chambers. While gas samples are taken, measurement deviations become more evident according to the used chamber design especially when external disturbances occur. This paper studies the carbon dioxide concentration profiles within the top soil layers, and investigates the controlling factors affecting the process. The considered factors are diffusion, temperature and viscosity. The efflux equation is discussed and then it is linked with the soils geotechnical parameters, while a relationship between the Reynolds number within the soil and efflux is found. Emphasis on the importance of the external geometrical design considerations is shown through studying external boundary layer effects due to the chamber outer shell shape and how it interacts with blowing winds. Chamber stability on site of deployment is also of a significant importance considering external blowing winds. Internal geometrical considerations are linked with the flow turbulence within the dynamic chambers. It is highly recommended that respiration chamber designers need to work in parallel with a multidisciplinary team in order to make a chamber design that ensures the least disturbance to occur at the location of study