On the crashworthiness performance of thin-walled energy absorbers: Recent advances and future developments

Over the past several decades, a noticeable amount of research efforts has been directed to minimising injuries and death to people inside a structure that is subjected to an impact loading. Thin-walled (TW) tubular components have been widely employed in energy absorbing structures to alleviate the detrimental effects of an impact loading during a collision event and thus enhance the crashworthiness performance of a structure. Comprehensive knowledge of the material properties and the structural behaviour of various TW components under various loading conditions is essential for designing an effective energy absorbing system. In this paper, based on a broad survey of the literature, a comprehensive overview of the recent developments in the area of crashworthiness performance of TW tubes is given with a special focus on the topics that emerged in the last ten years such as crashworthiness optimisation design and energy absorbing responses of unconventional TW components including multi-cells tubes, functionally graded thickness tubes and functionally graded foam filled tubes. Due to the huge number of studies that analysed and assessed the energy absorption behaviour of various TW components, this paper presents only a review of the crashworthiness behaviour of the components that can be used in vehicles structures including hollow and foam-filled TW tubes under lateral, axial, oblique and bending loading

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

Design and development of proton exchange membrane fuel cell using open pore cellular foam as flow plate material

This paper reports the design and development of a Proton Exchange Membrane (PEM) fuel cell using open pore cellular metal foam as the flow plate material. Effective housing designs are proposed for both hydrogen and oxygen sides and through the application of Computational Fluid Dynamic (CFD) modelling and analysis techniques the flow regime through the open pore cellular metal foam flow plate are identified. Based on the CFD results the best anode housing design was selected and manufactured. The fuel cell was assembled and tested and the findings are reported

Deformation and energy absorption of additively manufactured functionally graded thickness thin-walled circular tubes under lateral crushing

This is an accepted manuscript of an article published by Elsevier in Engineering Structures on 10/10/2020, available online: https://doi.org/10.1016/j.engstruct.2020.111324 The accepted version of the publication may differ from the final published versionFunctionally graded thickness (FGT) is an innovative concept to create light-weight structures with better material distribution and promising energy absorption characteristics suitable for vehicle crashworthiness applications. Accordingly, this paper suggests innovative circular tubes with in-plane thickness gradient along their perimeter and assesses their crashworthiness behaviour under lateral loading. Three different designs of circular tubes with thickness gradient were considered in which the locations of maximum and minimum thicknesses are varied. Selective laser melting method of additive manufacturing was used to manufacture the different tubes. Two different bulk powders including titanium (Ti6Al4V) and aluminium (AlSi10Mg) were used in the manufacturing process. Quasi-static crush experiments were conducted on the laser melted tubes to investigate their crushing and energy absorption behaviour. The energy absorption characteristics of the different FGT tubes were calculated and compared against a uniform thickness design. The results revealed that the best crashworthiness metrics were offered by FGT titanium tube in which the maximum thickness regions were along the horizontal and vertical directions while the minimum thickness regions were at an angle of 45° with respect to the loading direction. The aforementioned tube was found to absorb 79% greater energy per unit mass than its uniform thickness counterpart. Finally, with the aid of numerical simulations and surrogate modelling techniques, multi-objective optimisation and parametric analysis were conducted on the best FGT tube. The influences of the geometrical parameters on the crashworthiness responses of the best FGT structure were explored and the optimal thickness gradient parameters were determined. The results reported in this paper provide valuable guidance on the design of FGT energy absorption tubes for lateral deformation.University of Wolverhampton early research award scheme (ERAS)Accepted versio

Compaction analysis and optimisation of convex-faced pharmaceutical tablets using numerical techniques

Capping failure, edge chipping, and non-uniform mechanical properties of convexfaced pharmaceutical tablets are common problems in pharma industry. In this paper, Finite Element Modelling (FEM) and Design of Experiment (DoE) techniques are adopted to find the optimal shape of convex-faced (CF) pharmaceutical tablet which has more uniform mechanical properties and less capping and chipping tendency. The effects of the geometrical parameters and friction on the compaction responses of convex-faced pharmaceutical tablets were first identified and analysed. The finite element model of the tabletting process was generated using the implicit code (ABAQUS) and validated against experimental measurements. Response Surface Methodology (RSM) was employed to establish the relationship between the design variables, represented by the geometrical parameters and the friction coefficient, and compaction responses of interest including residual die pressure, the variation of relative density within the tablet, and the relative shear stress of the edge of the tablet. A statistical-based optimisation approach is then employed to undertake shape optimisation of CF tablets. The obtained results demonstrated how the geometrical parameters of CF tablet and the friction coefficient have significant effects on the compaction behaviour and quality of the pharmaceutical tablet

Comprehensive investigation on hydrogen and fuel cell technology in the aviation and aerospace sectors

The world energy consumption is greatly influenced by the aviation industry with a total energy consumption ranging between 2.5% and 5%. Currently, liquid fossil fuel, which releases various types of Greenhouse Gas (GHG) emissions, is the main fuel in the aviation industry. As the aviation industry grows rapidly to meet the requirements of the increased world population, the demand for environmentally friendly power technology for various applications in the aviation sector has been increased sharply in recent years. Among the various clean power sources, energy obtained from hydrogen is considered the future for energy generation in the aviation industry due to its cleanness and abundance. This paper aims to give an overview of the potential aviation applications where hydrogen and fuel cell technology can be used. Also, the major challenges that limit the wide adoption of hydrogen technology in aviation are highlighted and future research prospects are identified

Hybrid metaheuristic algorithms: a recent comprehensive review with bibliometric analysis

Metaheuristic algorithms are widely used in various applications. Collaborating two or more algorithms in a hybrid form has shown great improvements in terms of the algorithm's performance. This paper highlights the recently published work during the last decade from a quantitative perspective. The biometric measures include the number of publications, citations, average citations per publication, h-index, and field-weighted citation impact (FWCI) based on the data extracted from the Scopus database. Statistical measures, co-occurrence and co-authorship maps, and illustrative graphs have been implemented using software tools. According to the collected data, about 3469 articles have been published during the last decade with an increasing rate of 44.1 papers per year. Most of these articles have been published as journal articles with a percentage of 68.3%, followed by conference articles occupied 29.5%. China, India and Iran contributed the largest number of articles at 1076, 965, and 239, respectively. Parouha, Verma, and Kamel, are the top-ranked authors with 14, 10, and 9 publications, respectively. The most areas of interest are computer science, engineering and mathematics with publication percentages of 27.69%, 25.55% and 13.91%, respectively. The data presented in this paper gives the researchers a clear image of this hot topic to start new research

Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment

Metallic-based bipolar plates exhibit several advantages over graphite-based plates, including higher strength, lower manufacturing cost and better electrical conductivity. However, poor corrosion resistance and high interfacial contact resistance (ICR) are major challenges for metallic bipolar plates used in proton exchange membrane (PEM) fuel cells. Corrosion of metallic parts in PEM fuel cells not only increases the interfacial contact resistance but it can also decrease the proton conductivity of the Membrane Electrode Assembly (MEA), due to catalyst poisoning phenomena caused by corrosive products. In this paper, a composite coating of polytetrafluoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast™ process. Corrosion resistance of the coated and uncoated metals in a simulated PEM fuel cell environment of 0.5 M H2SO4 + 2 ppm HF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paper was measured and used as an indicator of surface conductivity. Scanning Electron Microscopy (SEM), 3D microscopy, Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and contact angle measurements were used to characterise the samples. The results showed that the PTFE coating improved the hydrophobicity and corrosion resistance but increased the ICR of the coated metals due to the unconductive nature of such coating. Thus, it was concluded that it is not fully feasible to use the PTFE alone for coating metals for fuel cell applications and a hybrid coating consisting of PTFE and a conductive material is needed to improve surface conductivity.Enterprise Irelan

Sound pressure level of a Formula 3 car and the influence of detachable muffler-tip

© 2021 The Authors. Published by Elsevier. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1016/j.rineng.2021.100261This study presents the initial findings associated with the noise emission tests that were carried out in preparation of the UWR Formula 3 car. Even though Formula 3 (F3) race cars are excluded from road vehicle noise emission regulations (EU No. 540/2014), their emission is closely regulated by Fédération Internationale de l’Automobile (FIA) technical regulations. According to FIA regulations, the noise generated by participating cars must not exceed 110 dB (A-weighted) under specific test conditions. The acoustic tests presented in this study were carried out at RAF (Royal Air Force) Cosford airfield in the UK closely simulating FIA recommended conditions. The tests were established to characterise the noise emission of the car during drive-by and stationary conditions. In addition to measuring the Sound Pressure Level (SPL) emitted, the study was extended to evaluating the performance of a detachable muffler tip that is permitted under the FIA regulations. The study found that the tested muffler-tip did not reduce the LAeq acoustic emission under any of the test cases considered. Nevertheless, introducing muffler-tip worsened the LAeq levels by 0.2 dB which is within the standard acoustic measurement uncertainty. Overall, the paper establishes the noise levels associated with F3 cars and the requirement for customised muffler-tips as opposed to aftermarket ones for meaningful noise reduction without adversely affecting performance.Accepted versio

Crashworthiness design and optimisation of windowed tubes under axial impact loading

© 2019 Elsevier Ltd Thin-walled structures are frequently used as energy absorbers in the automotive, railway and aviation industries. This paper addresses the crashworthiness performance of thin-walled windowed tubes under dynamic impact loading. Different shapes of cut-outs were introduced to thin-walled tubes with different cross-sectional shapes to create windowed tubes. Explicit finite element code, LS-DYNA, was used to simulate the crushing behaviour of the windowed tubes under axial impact loading. The Finite Element (FE)model was validated by conducting experimental tests and showing that the numerical and experimental responses are comparable. The crashworthiness responses of the different windowed tubes were compared and the best performing tube was identified using a multi-criteria decision-making method known as Technique of Order Preference by Similarity to Ideal Solution (TOPSIS). It was found that a circular tube with a square window shape outperforms all other sections and exhibits the best energy absorption characteristics. Subsequently, a multi-objective optimisation analysis was performed to find the optimal configuration of the best tube. Response Surface Methodology (RSM)was used to develop models for the energy absorption responses of the tube. The design variables were selected to describe size, number, and distributions of the windows, while specific energy absorption (SEA)and peak crush force (PCF)were set as design responses. Parametric analysis was conducted to understand the effects of the design variables on the crashworthiness behaviour and the optimal configuration was identified.Accepted versio