• Computational simulation of the damage response for machining long fibre reinforced plastic (LFRP) composite parts: A review

      Wang, Xiaonan; Wang, Fuji; Gu, Tianyu; Jia, Zhenyuan; Shi, Yu; Dalian University of Technology; University of Chester
      Long fibre reinforced plastics (LFRPs) possess excellent mechanical properties and are widely used in the aerospace, transportation and energy sectors. However, their anisotropic and inhomogeneous characteristics as well as their low thermal conductivity and specific heat capacity make them prone to subsurface damage, delamination and thermal damage during the machining process, which seriously reduces the bearing capacity and shortens the service life of the components. To improve the processing quality of composites, finite element (FE) models were developed to investigate the material removal mechanism and to analyse the influence of the processing parameters on the damage. A review of current studies on composite processing modelling could significantly help researchers to understand failure initiation and development during machining and thus inspire scholars to develop new models with high prediction accuracy and computational efficiency as well as a wide range of applications. To this aim, this review paper summarises the development of LFRP machining simulations reported in the literature and the factors that can be considered in model improvement. Specifically, the existing numerical models that simulate the mechanical and thermal behaviours of LFRPs and LFRP-metal stacks in orthogonal cutting, drilling and milling are analysed. The material models used to characterise the constituent phases of the LFRP parts are reviewed. The mechanism of material removal and the damage responses during the machining of LFRP laminates under different tool geometries and processing parameters are discussed. In addition, novel and objective evaluations that concern the current simulation studies are conducted to summarise their advantages. Aspects that could be improved are further detailed, to provide suggestions for future research relating to the simulation of LFRP machining.
    • Design and finite element simulation of metal-core piezoelectric fiber/epoxy matrix composites for virus detection

      Wang, Yinli; Shi, Yu; Narita, Fumio; Tohoku University; University of Chester
      Undoubtedly, the coronavirus disease 2019 (COVID-19) has received the greatest concern with a global impact, and this situation will continue for a long period of time. Looking back in history, airborne transimission diseases have caused huge casualties several times. COVID-19 as a typical airborne disease caught our attention and reminded us of the importance of preventing such diseases. Therefore, this study focuses on finding a new way to guard against the spread of these diseases such as COVID-19. This paper studies the dynamic electromechanical response of metal-core piezoelectric fiber/epoxy matrix composites, designed as mass load sensors for virus detection, by numerical modelling. The dynamic electromechanical response is simulated by applying an alternating current (AC) electric field to make the composite vibrate. Furthermore, both concentrated and distributed loads are considered to assess the sensitivity of the biosensor during modelling of the combination of both biomarker and viruses. The design parameters of this sensor, such as the resonant frequency, the position and size of the biomarker, will be studied and optimized as the key values to determine the sensitivity of detection. The novelty of this work is to propose functional composites that can detect the viruses from changes of the output voltage instead of the resonant frequency change using piezoelectric sensor and piezoelectric actuator. The contribution of this detection method will significantly shorten the detection time as it avoids fast Fourier transform (FFT) or discrete Fourier transform (DFT). The outcome of this research offers a reliable numerical model to optimize the design of the proposed biosensor for virus detection, which will contribute to the production of high-performance piezoelectric biosensors in the future.
    • The diagnostic analysis of the fault coupling effects in planet bearing

      Xue, Song; Wang, Congsi; Howard, Ian; Lian, Peiyuan; Chen, Gaige; Wang, yan; Yan, Yuefei; Xu, Qian; Shi, Yu; Jia, Yu; et al. (Elsevier, 2019-11-09)
      The purpose of this paper is to investigate the fault coupling effects in the planet bearing as well as the corresponding vibration signatures in the resultant vibration spectrum. In a planetary gear application, the planet bearing can not only spin around the planet gear axis, but also revolve about the sun gear axis and this rotating mechanism poses a big challenge for the diagnostic analysis of the planet bearing vibration spectrum. In addition, the frequency component interaction and overlap phenomenon in the vibration spectrum caused by the fault coupling effect can even worsen the diagnosis results. To further the understanding of the fault coupling effects in a planet bearing, a 34° of freedom planetary gear model with detailed planet bearing model was established to obtain the dynamic response in the presence of various bearing fault scenarios. The method of modelling the bearing distributed faults and localized faults has been introduced in this paper, which can be further incorporated into the planetary gear model to obtain the faulted vibration signal. The “benchmark” method has been adopted to enhance the planet bearing fault impulses in the vibration signals and in total, the amplitude demodulation results from 20 planet bearing fault scenarios have been investigated and analyzed. The coherence estimation over the vibration frequency domain has been proposed as a tool to quantify the fault impact contribution from different fault modes and the results suggested that the outer raceway fault contributes most to the resultant planet bearing vibration spectrum in all the investigated fault scenarios.
    • Effect of laser treatment on the attachment and viability of mesenchymal stem cell responses on shape memory NiTi alloy

      Chan, Chi-Wai; Hussain, Issam; Waugh, David G.; Lawrence, Jonathan; Man, Hau-Chung; Queen's University, Belfast ; University of Lincoln ; University of Chester ; University of Chester ; Hong Kong Polytechnic University (Elsevier, 2014-05-22)
      The objectives of this study were to investigate the effect of laser-induced surface features on the morphology, attachment and viability of mesenchymal stem cells (MSCs) at different periods of time, and to evaluate the biocompatibility of different zones: laser-melted zone (MZ), heat-affected zone (HAZ) and base metal (BM) in laser-treated NiTi alloy.
    • Effect of surface micro-pits on mode-II fracture toughness of Ti-6Al-4V/PEEK interface

      Pan, Lei; Pang, Xiaofei; Wang, Fei; Huang, Haiqiang; Shi, Yu; Tao, Jie; Nanjing University of Aeronautics and Astronautics; University of Chester (Elsevier, 2019-08-17)
      Herein, the delamination issue of TiGr(TC4/PEEK/Cf) laminate is addressed by investigating the influence of TC4(Ti-6Al-4V) surface micro-pits on mode-II interfacial fracture toughness of TC4/PEEK interface through experimental and finite element modeling. The micro-pits unit cell, unit strip and the end notched flexure (ENF) models are established based on the finite element simulations and the effect of micro-pit size parameters is studied in detail. The results of micro-pits unit cell model reveal that the presence of micro-pits can effectively buffer the interfacial stress concentration under mode-II loading conditions. Furthermore, the micro-pits unit strip model, with different micro-pit sizes, is analyzed to obtain the interface parameters, which are converted and used in the ENF model. Both the unit strip and ENF models conclude that the presence of interfacial micro-pits effectively improves the mode-II fracture toughness. It is worth mentioning that the utilization of converted interface parameters in ENF model avoided the limitation of micro-pit size and reduced the workload. Finally, the experimental and computational ENF results exhibited excellent consistency and confirmed the reliability of the proposed finite element models. The current study provides useful guidelines for the design and manufacturing of high-performance TC4/PEEK interfaces for a wide range of applications.
    • Effects of inkjet printed toughener on delamination suppression in drilling of carbon fibre reinforced plastics (CFRPs)

      Shi, Yu; Wang, Xiaonan; Wang, Fuji; Gu, Tianyu; Xie, Pengheng; Jia, Yu; University of Chester; Dalian University of Technology; Aston University
      Delamination has been recognised as the predominant damage induced during the drilling of carbon fibre reinforced plastics (CFRPs). It could significantly reduce the bearing capacity and shorten the service life of the designed component. To enhance the delamination resistance of CFRPs for different applications, great affords have been done to improve their interlaminar fracture toughness. However, due to the difficulty in accurately controlling the amount of the toughener applied in the interface, effect of the toughener content on the toughening efficiency is rarely studied. In this work, an experimental research was developed to investigate the performance of the toughener on the improvement of delamination resistance in the drilling of CFRPs and parametrically optimise the toughener content with the consideration of different feed rates. Specifically, poly(methyl methacrylate) (PMMA) solutions with various concentrations were selected to add on the CFRP prepreg, and co-cured together with layups. The inkjet printing technology was adopted to deposit the PMMA solutions for precisely controlled toughener contents. Through drilling experiments on the toughened CFRPs, it was found that the optimal content of the PMMA solution was 10 wt% to offer the least delamination, in particular, for the situation under the highest feed rate condition. The toughing mechanisms were also concluded by analysing the histories of the thrust force and torque in the drilling process. The results of this study is significantly contribute to the locally toughening of the composite interfaces and the improvement of the drilling quality, which is specifically helpful to strengthen the joint property for the structural design stage for the aircraft.
    • Enhancing interfacial strength between AA5083 and cryogenic adhesive via anodic oxidation and silanization

      Lei, Pan; Zhang, Aiai; Zheng, Zengmin; Duan, Lixiang; Zhang, Lei; Shi, Yu; Tao, Jie; Nanjing University of Aeronautics and Astronautics; University of Chester (Elsevier, 2018-04-27)
      AA5083 aluminum alloy was treated in turn with phosphoric-sulfuric acid anodic oxidation and then with silanization using the silane coupling agent KH560. A chemical bond (Si-O-Al) was created between the aluminum alloy and silane film, and a dehydration condensation reaction occurred between the silane film and cryogenic adhesive to enhance the bonding strength between the aluminum alloy and the cryogenic adhesive. Scanning electron microscopy, Energy dispersive spectroscopy, and Fourier transform infrared spectroscopy were used to explore the interfacial characteristics of the aluminum alloy both with and without the applied treatment. Furthermore, single lap shear tests and durability tests were performed to assess the adhesive strength of the interface between the aluminum alloy and the cryogenic adhesive at low temperature. The most improved interfacial strength using the anodic oxidation and the silanization treatments reached 33.96 MPa at −60 °C. The interface strength with the same treatments after the durability test was 25.4 MPa.
    • Evaporation of liquid nitrogen droplets in superheated immiscible liquids

      Rebelo, Neville; Zhao, Huayong; Nadal, Francois; Garner, Colin; Williams, Andy; Loughborough University; University of Chester (Elsevier, 2019-08-22)
      Liquid nitrogen or other cryogenic liquids have the potential to replace or augment current energy sources in cooling and power applications. This can be done by the rapid evaporation and expansion processes that occur when liquid nitrogen is injected into hotter fluids in mechanical expander systems. In this study, the evaporation process of single liquid nitrogen droplets when submerged into n-propanol, methanol, n-hexane, and n-pentane maintained at 294 K has been investigated experimentally and numerically. The evaporation process is quantified by tracking the growth rate of the resulting nitrogen vapour bubble that has an interface with the bulk liquid. The experimental data suggest that the bubble volume growth is proportional to the time and the bubble growth rate is mainly determined by the initial droplet size. A comparison between the four different bulk liquids indicates that the evaporation rate in n-pentane is the highest, possibly due to its low surface tension. A scaling law based on the pure diffusion-controlled evaporation of droplet in open air environment has been successfully implemented to scale the experimental data. The deviation between the scaling law predictions and the experimental data for 2-propanol, methanol and n-hexane vary between 4% and 30% and the deviation for n-pentane was between 24% and 65%. The more detailed bubble growth rates have been modelled by a heuristic one-dimensional, spherically symmetric quasi-steady-state confined model, which can predict the growth trend well but consistently underestimate the growth rate. A fixed effective thermal conductivity is then introduced to account for the complex dynamics of the droplet inside the bubble and the subsequent convective processes in the surrounding vapour, which leads to a satisfactory quantitative prediction of the growth rate.
    • In vitro mesenchymal stem cell response to a CO2 laser modified polymeric material

      Waugh, David G.; Hussain, Issam; Lawrence, Jonathan; Smith, Graham C.; Toccaceli, Christina; University of Chester; University of Lincoln (Elsevier, 2016-05-16)
      With an ageing world population it is becoming significantly apparent that there is a need to produce implants and platforms to manipulate stem cell growth on a pharmaceutical scale. This is needed to meet the socio-economic demands of many countries worldwide. This paper details one of the first ever studies in to the manipulation of stem cell growth on CO2 laser surface treated nylon 6,6 highlighting its potential as an inexpensive platform to manipulate stem cell growth on a pharmaceutical scale. Through CO2 laser surface treatment discrete changes to the surfaces were made. That is, the surface roughness of the nylon 6,6 was increased by up to 4.3 µm, the contact angle was modulated by up to 5° and the surface oxygen content increased by up to 1 atom%. Following mesenchymal stem cell growth on the laser treated samples, it was identified that CO2 laser surface treatment gave rise to an enhanced response with an increase in viable cell count of up to 60,000 cells/ml when compared to the as-received sample. The effect of surface parameters modified by the CO2 laser surface treatment on the mesenchymal stem cell response is also discussed along with potential trends that could be identified to govern the mesenchymal stem cell response.
    • Laser surface modification of polymeric materials for microbiological applications

      Gillett, Alice R.; Waugh, David G.; Lawrence, Jonathan; University of Chester (Elsevier, 2016-04-15)
    • Laser surface structuring of ceramics, metals and polymers for biological applications: A review

      Shukla, Pratik; Waugh, David G.; Lawrence, Jonathan; University of Chester (Elsevier, 2014-10-14)
    • Lateral crushing and bending responses of CFRP square tube filled with aluminum honeycomb

      Liu, Qiang; Xu, Xiyu; Ma, Jingbo; Wang, Jinsha; Shi, Yu; Hui, David; Sun Yat-Sen University; Hunan University; University of Chester; University of New Orleans (Elsevier, 2017-03-18)
      This paper aims to investigate the lateral planar crushing and bending responses of carbon fiber reinforced plastic (CFRP) square tube filled with aluminum honeycomb. The various failure modes and mechanical characteristics of filled tube were experimentally captured and numerically predicted by commercial finite element (FE) package LS-DYNA, comparing to the hollow tubes. The filled aluminum honeycomb effectively improved the stability of progressive collapse during crushing, leading to both hinges symmetrically occurred along the vertical side. The experimental results showed that energy absorbed (EA) and specific energy absorption (SEA) of the filled CFRP tubes could be significantly increased to 6.56 and 4 times, respectively, of those measured for the hollow tubes without fillings under lateral crushing. Although an improvement of 32% of EA and 0.9% of SEA were obtained for the lateral bending, still the design using aluminum honeycomb as filling was remarkably capable to improve the mechanical characteristics of CFRP tube structure. A good agreement was obtained between experimentally measured and numerically predicted load-displacement histories. The FE prediction was also helpful in understanding the initiation and propagation of cracks within the filled CFRP structure.
    • Modelling impact damage in composite laminates: A simulation of intra- and inter-laminar cracking

      Pinna, Christophe; Soutis, Constantinos; Shi, Yu; University of Chester; University of Sheffield; University of Manchester (Elsevier, 2014-04-12)
      In this work, stress- and fracture mechanics-based criteria are developed to predict initiation and evolution, respectively, of intra- and inter-laminar cracking developed in composite laminates subjected to a relatively low energy impact (⩽15 J) with consideration of nonlinear shear behaviour. The damage model was implemented in the finite element (FE) code (Abaqus/Explicit) through a user-defined material subroutine (VUMAT). Delamination (or inter-laminar cracking) was modelled using interface cohesive elements while splitting and transverse matrix cracks (intralaminar cracking) that appeared within individual plies were also simulated by inserting cohesive elements along the fibre direction (at a crack spacing determined from experiments for computing efficiency). A good agreement is obtained when the numerically predicted results are compared to both experimentally obtained curves of impact force and absorbed energy versus time and X-ray radiography damage images, provided the interface element stiffness is carefully selected. This gives confidence to selected fracture criteria and assists to identify material fracture parameters that influence damage resistance of modern composite material systems.
    • Modelling transverse matrix cracking and splitting of cross-ply composite laminates under four point bending

      Shi, Yu; Soutis, Constantinos; University of Chester; University of Manchester (Elsevier, 2015-11-30)
      The transverse matrix cracking and splitting in a cross-ply composite laminate has been modelled using the finite element (FE) method with the commercial code Abaqus/Explicit 6.10. The equivalent constraint model (ECM) developed by Soutis et al. has been used for the theoretical prediction of matrix cracking and results have been compared to those obtained experimentally and numerically. A stress-based traction–separation law has been used to simulate the initiation of matrix cracks and their growth under mixed-mode loading. Cohesive elements have been inserted between the interfaces of every neighbouring element along the fibre orientation for all 0° and 90° plies to predict the matrix cracking and splitting at predetermined crack spacing based on experimental observations. Good agreement is obtained between experimental and numerical crack density profiles for different 90° plies. In addition, different mechanisms of matrix cracking and growth processes were captured and splitting was also simulated in the bottom 0° ply by the numerical model.
    • Multiphysics vibration FE model of piezoelectric macro fibre composite on carbon fibre composite structures

      Jia, Yu; Wei, Xueyong; Xu, Liu; Wang, Congsi; Lian, Peiyuan; Xue, Song; Alsaadi, Ahmed; Shi, Yu; University of Chester; Xi'an Jiaotong University; Xidian University (Elsevier, 2018-12-21)
      This paper presents a finite element (FE) model developed using commercial FE software COMSOL to simulate the multiphysical process of pieozoelectric vibration energy harvesting (PVEH), involving the dynamic mechanical and electrical behaviours of piezoelectric macro fibre composite (MFC) on carbon fibre composite structures. The integration of MFC enables energy harvesting, sensing and actuation capabilities, with applications found in aerospace, automotive and renewable energy. There is an existing gap in the literature on modelling the dynamic response of PVEH in relation to real-world vibration data. Most simulations were either semi-analytical MATLAB models that are geometry unspecific, or basic FE simulations limited to sinusoidal analysis. However, the use of representative environment vibration data is crucial to predict practical behaviour for industrial development. Piezoelectric device physics involving solid mechanics and electrostatics were combined with electrical circuit defined in this FE model. The structure was dynamically excited by interpolated vibration data files, while orthotropic material properties for MFC and carbon fibre composite were individually defined for accuracy. The simulation results were validated by experiments with <10﹪ deviation, providing confidence for the proposed multiphysical FE model to design and optimise PVEH smart composite structures.
    • A New Electrode Design Method in Piezoelectric Vibration Energy Harvesters to Maximize Output Power

      Du, Sijun; Jia, Yu; Chen, Shao-Tuan; Zhao, Chun; Sun, Boqian; Arroyo, Emmanuelle; Seshia, Ashwin A.; University of Cambridge; University of Chester (Elsevier, 2017-07-19)
      A resonant vibration energy harvester typically comprises of a clamped anchor and a vibrating shuttle with a proof mass. Piezoelectric materials are embedded in locations of high strain in order to transduce mechanical deformation into electrical charge. Conventional design for piezoelectric vibration energy harvesters (PVEH) usually utilizes piezoelectric materials and metal electrode layers covering the entire surface area of the cantilever with no consideration provided to examine the trade-off involved with respect to maximize output power. This paper reports on the theory and experimental verification underpinning optimization of the active electrode area in order to maximize output power. The calculations show that, in order to maximize the output power of a PVEH, the electrode should cover the piezoelectric layer from the peak strain area to a position, where the strain is a half of the average strain in all the previously covered area. With the proposed electrode design, the output power can be improved by 145% and 126% for a cantilever and a clamped-clamped beam, respectively. MEMS piezoelectric harvesters are fabricated to experimentally validate the theory.
    • Non-Exhaust Vehicle Emissions of Particulate Matter and VOC from Road Traffic: A Review

      Harrison, Roy; Allan, James; Caruthers, David; Heal, Matthew; Lewis, Alastair; Marner, Ben; Murrells, Tim; Williams, Andrew; University of Birmingham; University of Manchester; Cambridge Environmental Research Consultants; University of Edinburgh; University of York; Air Quality Consultants; Ricardo Energy and Environment; University of Chester; King Abdulaziz University (Elsevier, 2021-07-01)
      As exhaust emissions of particles and volatile organic compounds (VOC) from road vehicles have progressively come under greater control, non-exhaust emissions have become an increasing proportion of the total emissions, and in many countries now exceed exhaust emissions. Non-exhaust particle emissions arise from abrasion of the brakes and tyres and wear of the road surface, as well as from resuspension of road dusts. The national emissions, particle size distributions and chemical composition of each of these sources is reviewed. Most estimates of airborne concentrations derive from the use of chemical tracers of specific emissions; the tracers and airborne concentrations estimated from their use are considered. Particle size distributions have been measured both in the laboratory and in field studies, and generally show particles to be in both the coarse (PM2.5-10) and fine (PM2.5) fractions, with a larger proportion in the former. The introduction of battery electric vehicles is concluded to have only a small effect on overall road traffic particle emissions. Approaches to numerical modelling of non-exhaust particles in the atmosphere are reviewed. Abatement measures include engineering controls, especially for brake wear, improved materials (e.g. for tyre wear) and road surface cleaning and dust suppressants for resuspension. Emissions from solvents in screen wash and de-icers now dominate VOC emissions from traffic in the UK, and exhibit a very different composition to exhaust VOC emissions. Likely future trends in non-exhaust particle emissions are described.
    • On the study of oil paint adhesion on optically transparent glass: Conservation of reverse paintings on glass

      Bayle, M.; Waugh, David G.; Colston, Belinda J.; Lawrence, Jonathan; University of Chester (Elsevier, 2015-12-01)
      Reverse painting on glass is a technique which consists of applying a cold paint layer on the reverse-side of glass. The main challenge facing these artworks is the fragile adhesion of the pictorial layer – a simple movement can modify the appearance of the painting. This paper details a study into the adhesion parameters of pigments on glass and the comparison between different pigments. The relationships between the binder (linseed oil) with pigments and the glass with or without the use of an adhesive are studied. Physical analyses by surface characterisation have been carried out to better understand the influence of the pigment. The use of a sessile drop device, optical microscopy, scanning electron microscopy (SEM), a surface 3D profiler and a pencil hardness scratch tester were necessary to establish a comparison of the pictorial layer adhesion. A comparison of the effect of two adhesives; namely ox gall and gum arabic, has shown that the adhesion is not only linked to the physical parameters but that possible chemical reactions can influence the results. Finally, a treatment based on humidity-extreme storage has shown the weakness of some pictorial layers.
    • Parametric Study of Environmental Conditions on The Energy Harvesting Efficiency for The Multifunctional Composite Structures

      Wen, Tao; Ratner, Alon; Jia, Yu; Shi, Yu; University of Chester;University of Warwick; Aston University
      This paper presents a parametric study of the efficacy of an integrated vibration energy harvesting device under the environmental condition representative of an offshore wind turbine. A multifunctional glass fibre composite with an integrated Micro Fibre Composite (MFC) energy harvesting device was tested by swept sine vibration under environmental conditions that ranged from – 40°C to 70°C in temperature and 10%RH to 90%RH in humidity in order to characterise the sensitivity and dependence of energy harvesting on environmental conditions. Experimental vibration testing was complemented with theoretical analysis to investigate the relative contributions to the temperature dependence of energy harvesting. This included mechanical properties of the stiffness and strength of the cantilever structure and the electrical properties of the MFC transducer, including its dielectric constants and charge coefficients. An inverse proportionality was observed between the magnitude of harvested energy and the climatic temperature. The efficiency of energy harvesting was dominated by the stiffness of the cantilever, which displayed viscoelastic temperature dependence. The sample was also tested with a vibration profile obtained from a wind turbine in order to validate the temperature influence under typical service conditions. Numerical modal analysis was used to determine the shapes of resonance modes, the frequencies of which were temperature dependent. Humidity was observed to have a secondary influence on energy harvesting, with no significant short-term effect on the structural properties of the samples within the limits of the experimental method.
    • Predicting the critical heat flux in pool boiling based on hydrodynamic instability induced irreversible hot spots

      Zhao, Huayong; Williams, Andrew; Loughborough University; University of Chester (Elsevier, 2018-03-07)
      A new model, based on the experimental observation reported in the literature that CHF is triggered by the Irreversible Hot Spots (IHS), has been developed to predict the Critical Heat Flux (CHF) in pool boiling. The developed Irreversible Hot Spot (IHS) model can predict the CHF when boiling methanol on small flat surfaces and long horizontal cylinders of different sizes to within 5% uncertainty. It can also predict the effect of changing wettability (i.e. contact angle) on CHF to within 10% uncertainty for both hydrophilic and hydrophobic surfaces. In addition, a linear empirical correlation has been developed to model the bubble growth rate as a function of the system pressure. The IHS model with this linear bubble growth coefficient correlation can predict the CHF when boiling water on both flat surfaces and long horizontal cylinders to within 5% uncertainty up to 10 bar system pressure, and the CHF when boiling methanol on a flat surface to within 10% uncertainty up to 5 bar. The predicted detailed bubble grow and merge process from various sub-models are also in good agreement with the experimental results reported in the literature.