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  • Journal article
    Del Linz P, Hooper PA, Arora H, Wang Y, Smith D, Blackman BRK, Dear JPet al., 2016,

    Delamination properties of laminated glass windows subject to blast loading

    , International Journal of Impact Engineering, Vol: 105, Pages: 39-53, ISSN: 1879-3509

    Delamination processes absorb significant amounts of energy in laminated glass windows when they are subjected to blast loads. Blast tests were performed previously and their results had been used to calculate the loads imposed on the support systems. In this research, the delamination process at realistic deformation rates was studied to understand the reaction force response obtained. Laboratory tensile tests were performed on pre-cracked laminated glass specimens to investigate their delamination behaviour. The experiments confirmed the presence of a plateau in the force-deflection graphs, suggesting that the delamination process absorbed significant energy. The experimental results were then employed to calibrate FEA models of the delamination process with the aim of estimating the delamination energy of the polyvinyl butyral (PVB) membrane and glass layers and its relationship with deformation speed. The delamination energies obtained through this research, if used with the appropriate PVB material model, are a valuable new tool new tool in the modelling and design of laminated glass façade structures.

  • Conference paper
    Campos-Pires R, Armstrong S, Sebastiani A, Luh C, Gruss M, Radyushkin K, Hirnet T, Engelhard K, Franks NP, Thal SC, Dickinson Ret al., 2016,

    Xenon provides short-term and long-term neuroprotection in a rodent model of traumatic brain injury

    , International Brain Injury Association’s Eleventh World Congress on Brain Injury, Publisher: Taylor & Francis, Pages: 653-653, ISSN: 1362-301X
  • Conference paper
    Harris K, Armstrong S, Campos-Pires R, Kiru L, Franks N, Dickinson Ret al., 2016,

    Neuroprotection against traumatic brain injury by xenon, but not argon, is mediated by inhibition at the N-methyl-D-aspartate receptor glycine site

    , International Brain Injury Association’s Eleventh World Congress on Brain Injury, Publisher: Taylor & Francis, Pages: 606-606, ISSN: 1362-301X
  • Journal article
    Reichenbach CS, Braiman C, Schiff ND, Hudspeth AJ, Reichenbach JDTet al., 2016,

    The auditory-brainstem response to continuous, non repetitive speech is modulated by the speech envelope and reflects speech processing

    , Frontiers in Computational Neuroscience, Vol: 10, ISSN: 1662-5188

    The auditory-brainstem response (ABR) to short and simple acoustical signals is an important clinical tool used to diagnose the integrity of the brainstem. The ABR is also employed to investigate the auditory brainstem in a multitude of tasks related to hearing, such as processing speech or selectively focusing on one speaker in a noisy environment. Such research measures the response of the brainstem to short speech signals such as vowels or words. Because the voltage signal of the ABR has a tiny amplitude, several hundred to a thousand repetitions of the acoustic signal are needed to obtain a reliable response. The large number of repetitions poses a challenge to assessing cognitive functions due to neural adaptation. Here we show that continuous, non-repetitive speech, lasting several minutes, may be employed to measure the ABR. Because the speech is not repeated during the experiment, the precise temporal form of the ABR cannot be determined. We show, however, that important structural features of the ABR can nevertheless be inferred. In particular, the brainstem responds at the fundamental frequency of the speech signal, and this response is modulated by the envelope of the voiced parts of speech. We accordingly introduce a novel measure that assesses the ABR as modulated by the speech envelope, at the fundamental frequency of speech and at the characteristic latency of the response. This measure has a high signal-to-noise ratio and can hence be employed effectively to measure the ABR to continuous speech. We use this novel measure to show that the auditory brainstem response is weaker to intelligible speech than to unintelligible, time-reversed speech. The methods presented here can be employed for further research on speech processing in the auditory brainstem and can lead to the development of future clinical diagnosis of brainstem function.

  • Book chapter
    Newell N, Masouros SD, 2016,

    Testing and development of mitigation systems for tertiary blast

    , Blast Injury Science and Engineering A Guide for Clinicians and Researchers, Editors: Bull, Clasper, Mahoney, Publisher: Springer, Pages: 249-255, ISBN: 9783319218670

    Biomechanics in blast is a key discipline in blast injury science and engineering that addresses the consequences of high forces, large deformations and extreme failure and thus relates closely to knowledge of materials science (Chap. 3) and ...

  • Book chapter
    Campos-Pires R, Dickinson R, 2016,

    Modelling Blast Brain Injury

    , Blast Injury Science and Engineering A Guide for Clinicians and Researchers, Editors: Clasper, Bull, Mahoney, Publisher: Springer, Pages: 173-182, ISBN: 9783319218670

    The consequences of blast traumatic brain injury (blast-TBI) in humans are largely determined by the characteristics of the trauma insult and, within certain limits, the individual responses to the lesions inflicted (1). In blast-TBI the mechanisms of brain vulnerability to the detonation of an explosive device are not entirely understood. They most likely result from a combination of the different physical aspects of the blast phenomenon, specifically extreme pressure oscillations (blast-overpressure wave), projectile penetrating fragments and acceleration-deceleration forces, creating a spectrum of brain injury that ranges from mild to severe blast-TBI (2). The pathophysiology of penetrating and inertially-driven blast-TBI has been extensively investigated for many years. However, the brain damage caused by blast-overpressure is much less understood and is unique to this type of TBI (3). Indeed, there continues to be debate about how the pressure wave is transmitted and reflected through the brain and how it causes cellular damage (4). No single model can mimic the clinical and mechanical complexity resulting from a real life blast-TBI (3). The different models, non-biological (in silico or surrogate physical) and biological (ex vivo, in vitro or in vivo), tend to complement each other.

  • Book chapter
    Carpanen D, Masouros SD, Newell N, 2016,

    Surrogates of human injury

    , Blast injury science and engineering, Editors: Bull, Clasper, Mahoney, Publisher: Springer, Pages: 189-199

    In this chapter we will explore surrogates that are being used to help in our understanding of the pathophysiology of human injury and of predicting injury risk when exposed to a set loading environment. We will mainly focus on anthropomorphic test devices (ATDs), usually known as dummies. Dummies are physical human surrogates that have been designed to evaluate occupant protection in response to collision. Even though ATDs are classified according to size, age, sex and impact direction, injury assessment in automotive and blast applications is mostly conducted using the adult midsize dummy.

  • Journal article
    Spurrier E, Gibb I, Masouros S, Clasper Jet al., 2016,

    Identifying spinal injury patterns in underbody blast to develop mechanistic hypotheses

    , Spine, Vol: 41, Pages: E268-E275, ISSN: 1528-1159

    Study Design. A retrospective case series of UK victims of blast injury.Objective. To identify the injury patterns in the spine caused by under-vehicle blast, and attempt to derive the mechanism of those injuries.Summary of Background Data. The Improvised Explosive Device has been a feature of recent conflicts with frequent attacks on vehicles, leading to devastating injuries. Vehicle design has evolved to reduce the risk of injury to occupants in underbody blast, where the device detonates beneath the vehicle. The mechanism of spinal injury in such attacks is not well understood; understanding the injury mechanism is necessary to produce evidence-based mitigation strategies.Methods. A Joint Theatre Trauma Registry search identified UK victims of blast between 2008 and 2013. Each victim had their initial scan reviewed to classify spinal fractures.Results. Seventy-eight victims were identified, of whom 53 were survivors. There were a total of 284 fractures, including 101 thoracolumbar vertebral body fractures and 39 cervical spine fractures. Most thoracolumbar fractures were wedge compression injuries. Most cervical spine fractures were compression-extension injuries.The most common thoracic and lumbar body fractures in this group suggest a flexed posture at the time of injury. Most cervical spine fractures were in extension, which might be compatible with the head having struck another object.Conclusion. Modifying the seated posture might reduce the risk of thoracolumbar injury, or allow the resulting injury patterns to be controlled. Cervical spine injuries might be mitigated by changing vehicle design to protect the head.

  • Journal article
    Newell N, Salzar R, Bull AMJ, Masouros SDet al., 2016,

    A validated numerical model of a lower limb surrogate to investigate injuries caused by under-vehicle explosions

    , Journal of Biomechanics, Vol: 49, Pages: 710-717, ISSN: 1873-2380

    Under-vehicle explosions often result in injury of occupants׳ lower extremities. The majority of these injuries are associated with poor outcomes. The protective ability of vehicles against explosions is assessed with Anthropometric Test Devices (ATDs) such as the MIL-Lx, which is designed to behave in a similar way to the human lower extremity when subjected to axial loading. It incorporates tibia load cells, the response of which can provide an indication of the risk of injury to the lower extremity through the use of injury risk curves developed from cadaveric experiments. In this study an axisymmetric finite element model of the MIL-Lx with a combat boot was developed and validated. Model geometry was obtained from measurements taken using digital callipers and rulers from the MIL-Lx, and using CT images for the combat boot. Appropriate experimental methods were used to obtain material properties. These included dynamic, uniaxial compression tests, quasi-static stress-relaxation tests and 3 point bending tests. The model was validated by comparing force-time response measured at the tibia load cells and the amount of compliant element compression obtained experimentally and computationally using two blast-injury experimental rigs. Good correlations between the numerical and experimental results were obtained with both. This model can now be used as a virtual test-bed of mitigation designs and in surrogate device development.

  • Journal article
    Eftaxiopoulou T, Barnett-Vanes A, Arora H, Macdonald W, Nguyen TTN, Itadani M, Sharrock AE, Britzman D, Proud WG, Bull AMJ, Rankin SMet al., 2016,

    Prolonged but not short duration blast waves elicit acute inflammation in a rodent model of primary blast limb trauma

    , Injury, Vol: 47, Pages: 625-632, ISSN: 0020-1383

    BackgroundBlast injuries from conventional and improvised explosive devices account for 75% of injuries from current conflicts; of these over 70% involve the limbs. Variable duration and magnitude of blast wave loading occurs in real-life explosions and is hypothesised to cause different injuries. While a number of in-vivo models report the inflammatory response to blast injuries, the extent of this response has not been investigated with respect to the duration of the primary blast wave. The relevance is that explosions in open air are of short duration compared to those in confined spaces. MethodsHind limbs of adult Sprauge-Dawley rats were subjected to focal isolated primary blast waves of varying overpressure (1.8-3.65kPa) and duration (3.0-11.5ms), utilising a shock tube and purpose built experimental rig. Rats were monitored during and after blast. At 6 and 24hrs after exposure blood, lungs, liver and muscle tissue were collected and prepared for histology and flow cytometry.ResultsAt 6hrs increases in circulating neutrophils and CD43Lo/His48Hi monocytes were observed in rats subjected to longer duration blast waves. This was accompanied by increases in circulating pro-inflammatory chemo/cytokines KC and IL-6. No changes were observed with shorter duration blast waves irrespective of overpressure. In all cases, no histological damage was observed in muscle, lung or liver. By 24hrs post-blast all inflammatory parameters had normalised. ConclusionsWe report the development of a rodent model of primary blast limb trauma that is the first to highlight an important role played by blast wave duration and magnitude in initiating acute inflammatory response following limb injury in the absence of limb fracture or penetrating trauma. The combined biological and mechanical method developed can be used to further understand the complex effects of blast waves in a range of different tissues and organs in-vivo.

  • Journal article
    Ding Z, Nolte D, Tsang CK, Cleather DJ, Kedgley AE, Bull AMet al., 2015,

    In Vivo Knee Contact Force Prediction Using Patient-Specific Musculoskeletal Geometry in a Segment-Based Computational Model.

    , Journal of Biomechanical Engineering-Transactions of the ASME, Vol: 138, ISSN: 0148-0731

    Segment-based musculoskeletal models allow the prediction of muscle, ligament and joint forces without making assumptions regarding joint degrees of freedom. The dataset published for the "Grand Challenge Competition to Predict In Vivo Knee Loads" provides directly-measured tibiofemoral contact forces for activities of daily living. For the "Sixth Grand Challenge Competition to Predict In Vivo Knee Loads", blinded results for "smooth" and "bouncy" gait trials were predicted using a customised patient-specific musculoskeletal model. For an unblinded comparison the following modifications were made to improve the predictions: • further customisations, including modifications to the knee centre of rotation; • reductions to the maximum allowable muscle forces to represent known loss of strength in knee arthroplasty patients; and • a kinematic constraint to the hip joint to address the sensitivity of the segment-based approach to motion tracking artefact. For validation, the improved model was applied to normal gait, squat and sit-to-stand for three subjects. Comparisons of the predictions with measured contact forces showed that segment-based musculoskeletal models using patient-specific input data can estimate tibiofemoral contact forces with root mean square errors (RMSEs) of 0.48-0.65 times body weight (BW) for normal gait trials. Tibiofemoral contact force patterns were estimated with an average coefficient of determination of 0.81 and with RMSEs of 0.46-1.01 times BW for squatting and 0.70-0.99 times BW for sit-to-stand tasks. This is comparable to the best validations in the literature using alternative models.

  • Journal article
    Villette CC, Phillips ATM, 2015,

    Informing phenomenological structural bone remodelling with a mechanistic poroelastic model

    , Biomechanics and Modeling in Mechanobiology, Vol: 15, Pages: 69-82, ISSN: 1617-7959

    t Studies suggest that fluid motion in the extracellularspace may be involved in the cellular mechanosensitivityat play in the bone tissue adaptation process. Previously,the authors developed a mesoscale predictive structuralmodel of the femur using truss elements to represent trabecularbone, relying on a phenomenological strain-basedbone adaptation algorithm. In order to introduce a responseto bending and shear, the authors considered the use of beamelements, requiring a new formulation of the bone adaptationdrivers. The primary goal of the study presented herewas to isolate phenomenological drivers based on the resultsof a mechanistic approach to be used with a beam elementrepresentation of trabecular bone in mesoscale structuralmodelling. A single-beam model and a microscale poroelasticmodel of a single trabecula were developed. A mechanisticiterative adaptation algorithm was implemented based onfluid motion velocity through the bone matrix pores to predictthe remodelled geometries of the poroelastic trabeculaunder 42 different loading scenarios. Regression analyseswere used to correlate the changes in poroelastic trabeculathickness and orientation to the initial strain outputsof the beam model. Linear (R2 > 0.998) and third-orderpolynomial (R2 > 0.98) relationships were found betweenchange in cross section and axial strain at the central axis,and between beam reorientation and ratio of bending strainto axial strain, respectively. Implementing these relationships into the phenomenological predictive algorithm for themesoscale structural femur has the potential to produce amodel combining biofidelic structure and mechanical behaviourwith computational efficiency.

  • Journal article
    Del Linz P, Hooper PA, Arora H, Smith D, Pascoe L, Cormie D, Blackman BRK, Dear JPet al., 2015,

    Reaction forces of laminated glass windows subject to blast loads

    , Composite Structures, Vol: 131, Pages: 193-206, ISSN: 1879-1085

    Several blast trials on laminated glass windows have been performed in the past, using both full field 3D Digital Image Correlation and strain gauges located on the supporting structure to collect information on the glass pane behaviour. The data obtained during three blast experiments were employed to calculate reaction forces throughout the perimeter supports both before and after the fracture of the glass layers. The pre-crack experimental data were combined with finite element modelling results to achieve this, whilst solely experimental results were employed for post-cracked reactions. The results for the three blast experiments were compared to identify similarities in their behaviour. It is intended that the results can be used to improve the existing spring–mass systems used for the design of blast resistant windows.

  • Book chapter
    Masouros S, Halewood C, Bull A, Amis Aet al., 2015,

    Biomechanics

    , Expertise orthopadie und unfallchirurgie: Knie, Editors: Kohn, ISBN: 978-3-1317500-1-3
  • Journal article
    Proud WG, Nguyen T-TN, Bo C, Butler BJ, Boddy RL, Williams A, Masouros S, Brown KAet al., 2015,

    The High-Strain Rate Loading of Structural Biological Materials

    , METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, Vol: 46A, Pages: 4559-4566, ISSN: 1073-5623
  • Journal article
    Spurrier E, Singleton JAG, Gibb I, Masouros S, Clasper Jet al., 2015,

    Blast Injury in the Spine: Dynamic Response Index Is Not an Appropriate Model for Predicting Injury

    , CLINICAL ORTHOPAEDICS AND RELATED RESEARCH, Vol: 473, Pages: 2929-2935, ISSN: 0009-921X
  • Journal article
    Arora H, Tarleton E, Li-Mayer J, Charalambides M, Lewis Det al., 2015,

    Modelling the damage and deformation process in a plastic bonded explosive microstructure under tension using the finite element method

    , Computational Materials Science, Vol: 110, Pages: 91-101, ISSN: 0927-0256

    Modelling the deformation and failure processes occurring in polymer bonded explosives (PBX)and other energetic materials is of great importance for processing methods and lifetime storagepurposes. Crystal debonding is undesirable since this can lead to contamination and a reductionin mechanical properties. An insensitive high explosive (PBX-1) was the focus of the study.This binary particulate composite consists of (TATB) filler particles encapsulated in a polymericbinder (KELF800). The particle/matrix interface was characterised with a bi-linear cohesive law,the filler was treated as elastic and the matrix as visco-hyperelastic. Material parameters weredetermined experimentally for the binder and the cohesive parameters were obtained previouslyfrom Williamson et al. (2014) and Gee et al. (2007) for the interface. Once calibrated, the materiallaws were implemented in a finite element model to allow the macroscopic response of thecomposite to be simulated. A finite element mesh was generated using a SEM image to identifythe filler particles which are represented as a set of 2D polygons. Simulated microstructureswere also generated with the same size distribution and volume fraction only with the idealisedassumption that the particles are a set of circles in 2D and spheres in 3D. The various modelresults were compared and a number of other variables were examined for their influence on theglobal deformation behaviour such as strain rate, cohesive parameters and contrast between fillerand matrix modulus. The overwhelming outcome is that the geometry of the particles plays acrucial role in determining the onset of failure and the severity of fracture in relation to whetherit is a purely local or global failure. The model was validated against a set of uniaxial tensiletests on PBX-1 and it was found that it predicted the initial modulus and failure stress and strainwell.Keywords: Particulate composites, High volume fraction, Finite Element Analysis,Micromechanics, Fract

  • Journal article
    Kelly M, Arora H, Worley A, Kaye M, Del Linz P, Hooper PA, Dear JPet al., 2015,

    Sandwich panel cores for blast applications: materials and graded density

    , Experimental Mechanics, Vol: 56, ISSN: 1741-2765

    Sandwich composites are of interest in marine applications dueto their high strength-to-weight ratio and tailorable mechanical properties, but their resistance to air blast loading is not well understood. Full-scale 100 kg TNT equivalent air blast testing at a 15 m stand-off distance wasperformed on glass-fibre reinforced polymer (GFRP) sandwich panels withpolyvinyl chloride (PVC); polymethacrylimid (PMI); and styrene acrylonitrile(SAN) foam cores, all possessing the same thickness and density. Further testingwas performed to assess the blast resistance of a sandwich panel containinga stepwise graded density SAN foam core, increasing in density away from theblast facing side. Finally a sandwich panel containing compliant polypropylene(PP) fibres within the GFRP front face-sheet, was subjected to blast loadingwith the intention of preventing front face-sheet cracking during blast. Measurementsof the sandwich panel responses were made using high-speed digital image correlation (DIC), and post-blast damage was assessed by sectioning thesandwich panels and mapping the damage observed. It was concluded that allcores are effective in improving blast tolerance and that the SAN core wasthe most blast tolerant out of the three foam polymer types, with the DIC resultsshowing a lower deflection measured during blast, and post-blast visualinspections showing less damage suffered. By grading the density of the core itwas found that through thickness crack propagation was mitigated, as well asdamage in the higher density foam layers, thus resulting in a smoother backface-sheet deflection profile. By incorporating compliant PP fibres into thefront face-sheet, cracking was prevented in the GFRP, despite damage beingpresent in the core and the interfaces between the core and face-sheets.

  • Journal article
    Reichenbach JDT, Meltzer B, Reichenbach CS, Braiman C, Schiff ND, Hudspeth AJet al., 2015,

    The steady-state response of the cerebral cortex to the beat of music reflects both the comprehension of music and attention

    , Frontiers in Human Neuroscience, Vol: 9, ISSN: 1662-5161

    The brain's analyses of speech and music share a range of neural resources and mechanisms. Music displays a temporal structure of complexity similar to that of speech, unfolds over comparable timescales, and elicits cognitive demands in tasks involving comprehension and attention. During speech processing, synchronized neural activity of the cerebral cortex in the delta and theta frequency bands tracks the envelope of a speech signal, and this neural activity is modulated by high-level cortical functions such as speech comprehension and attention. It remains unclear, however, whether the cortex also responds to the natural rhythmic structure of music and how the response, if present, is influenced by higher cognitive processes. Here we employ electroencephalography (EEG) to show that the cortex responds to the beat of music and that this steady-state response reflects musical comprehension and attention. We show that the cortical response to the beat is weaker when subjects listen to a familiar tune than when they listen to an unfamiliar, nonsensical musical piece. Furthermore, we show that in a task of intermodal attention there is a larger neural response at the beat frequency when subjects attend to a musical stimulus than when they ignore the auditory signal and instead focus on a visual one. Our findings may be applied in clinical assessments of auditory processing and music cognition as well as in the construction of auditory brain-machine interfaces.

  • Journal article
    Cleather DJ, Bull AM, 2015,

    The development of a segment-based musculoskeletal model of the lower limb: introducing FreeBody.

    , Royal Society Open Science, Vol: 2, ISSN: 2054-5703

    Traditional approaches to the biomechanical analysis of movement are joint-based; that is the mechanics of the body are described in terms of the forces and moments acting at the joints, and that muscular forces are considered to create moments about the joints. We have recently shown that segment-based approaches, where the mechanics of the body are described by considering the effect of the muscle, ligament and joint contact forces on the segments themselves, can also prove insightful. We have also previously described a simultaneous, optimization-based, musculoskeletal model of the lower limb. However, this prior model incorporates both joint- and segment-based assumptions. The purpose of this study was therefore to develop an entirely segment-based model of the lower limb and to compare its performance to our previous work. The segment-based model was used to estimate the muscle forces found during vertical jumping, which were in turn compared with the muscular activations that have been found in vertical jumping, by using a Geers' metric to quantify the magnitude and phase errors. The segment-based model was shown to have a similar ability to estimate muscle forces as a model based upon our previous work. In the future, we will evaluate the ability of the segment-based model to be used to provide results with clinical relevance, and compare its performance to joint-based approaches. The segment-based model described in this article is publicly available as a GUI-based Matlab® application and in the original source code (at www.msksoftware.org.uk).

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