ORCID Profile
0000-0002-8170-0775
Current Organisation
Swinburne University of Technology
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Civil Engineering | Biomechanical Engineering | Solid Mechanics | Structural Engineering
Emerging Defence Technologies | Expanding Knowledge in Engineering |
Publisher: Informa UK Limited
Date: 13-12-2013
DOI: 10.1080/10255842.2013.864641
Abstract: This study employs both the traditional and the complex modal analyses of a detailed finite element model of human head-neck system to determine modal responses in terms of resonant frequencies and mode shapes. It compares both modal responses without ignoring mode shapes, and these results are reasonably in agreement with the literature. Increasing displacement contour loops within the brain in higher frequency modes probably exhibits the shearing and twisting modes of the brain. Additional and rarely reported modal responses such as 'mastication' mode of the mandible and flipping mode of nasal lateral cartilages are identified. This suggests a need for detailed modelling to identify all the additional frequencies of each in idual part. Moreover, it is found that a d ing factor of above 0.2 has lifying effect in reducing higher frequency modes, while a diminishing effect in lowering peak biomechanical responses, indicating the importance of identifying the appropriate optimised d ing factor.
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.AAP.2015.03.012
Abstract: In spite of anatomic proximity of the facial skeleton and cranium, there is lack of information in the literature regarding the relationship between facial and brain injuries. This study aims to correlate brain injuries with facial injuries using finite element method (FEM). Nine common impact scenarios of facial injuries are simulated with their in idual stress wave propagation paths in the facial skeleton and the intracranial brain. Fractures of cranio-facial bones and intracranial injuries are evaluated based on the tolerance limits of the biomechanical parameters. General trend of maximum intracranial biomechanical parameters found in nasal bone and zygomaticomaxillary impacts indicates that severity of brain injury is highly associated with the proximity of location of impact to the brain. It is hypothesized that the midface is capable of absorbing considerable energy and protecting the brain from impact. The nasal cartilages dissipate the impact energy in the form of large scale deformation and fracture, with the vomer-ethmoid erging stress to the "crumpling zone" of air-filled sphenoid and ethmoidal sinuses in its most natural manner, the face protects the brain. This numerical study hopes to provide surgeons some insight in what possible brain injuries to be expected in various scenarios of facial trauma and to help in better diagnosis of unsuspected brain injury, thereby resulting in decreasing the morbidity and mortality associated with facial trauma.
Publisher: Elsevier BV
Date: 08-2019
Publisher: American Chemical Society (ACS)
Date: 20-06-2023
Publisher: Elsevier BV
Date: 09-2022
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 04-2021
Publisher: Wiley
Date: 22-07-2010
DOI: 10.1002/LARY.20976
Abstract: A septal L-strut is often preserved or created during septoplasty. The main intention is to provide structural stability and to straighten the nasal septum. Deformity or excessive deformation of the L-strut might cause functional or aesthetic complications. The objectives were to examine the effects of material properties, the boundary conditions, the nasal tip support, and the geometry of the L-struts on the deformity of septal L-struts. Computer-aided modeling was used to create a spring-supported nasal tip and free nasal tip L strut septal cartilage models upon which simulation was performed to analyse the deformation patterns. A five-sided septum model was first created from the computed tomography scan of a human subject. Several models with various combinations of wider or narrower dorsal struts as well as arc of cartilage were then constructed from this septum model. The edges connected to bony supports were assumed to be fixed, and the nasal tip was assumed to be spring supported. Finite element analyses were carried out to determine the deformation and stress distribution in the septal strut for different combinations of material properties and nasal tip spring support. The spring-supported nasal tip model provides a more accurate representation of the boundary conditions in the nose. In both the free and spring-supported nasal tips-the BC junction and the nasal spine are found to be the consistent points of maximum stress regardless of material properties. The preservation of an arc of cartilage and a wider dorsal strut increase the stability of the structure. The introduction of a spring-supported nasal tip model provided a more accurate representation of the boundary conditions in the nose. The bony-cartilaginous junction and the nasal spine were found to be the consistent points of maximum stress, regardless of material properties. The preservation of an arc of cartilage and a wider dorsal strut increased the stability of the structure.
Publisher: Elsevier BV
Date: 08-2020
Publisher: IEEE
Date: 03-2014
Publisher: Springer Science and Business Media LLC
Date: 24-08-2023
DOI: 10.1038/S41598-023-40286-3
Abstract: Fracture toughness of the human cornea is one of the critical parameters in suture-involved corneal surgeries and the development of bioengineered mimetics of the human cornea. The present article systematically studied the fracture characteristics of the human cornea to evaluate its resistance to tear in the opening (Mode-I) and trouser tear mode (Mode-III). Tear experiments reveal the dependency of the fracture behavior on the notch size and its location created in the corneal specimens. The findings indicate lamellar tear and collagen fiber pull-out as a failure mechanism in trouser tear and opening mode tests, respectively. Experimental results have shown a localized variation of tear behavior in trouser tear mode and indicated an increasing resistance to tear from the corneal center to the periphery. This article demonstrated the complications of evaluating fracture toughness in opening mode and showed that the limbus was weaker than the cornea and sclera against tearing. The overall outcomes of the present study help in designing experiments to understand the toughness of the diseased tissues, understanding the effect of the suturing location and donor placement, and creating numerical models to study parameters affecting corneal replacement surgery.
Publisher: Springer Science and Business Media LLC
Date: 24-10-2023
Publisher: Springer International Publishing
Date: 2014
Publisher: Wiley
Date: 14-06-2023
Abstract: The use of light for therapeutic applications requires light‐absorption by cellular chromophores at the target tissues and the subsequent photobiomodulation (PBM) of cellular biochemical processes. For transdermal deep tissue light therapy (tDTLT) to be clinically effective, a sufficiently large number of photons must reach and be absorbed at the targeted deep tissue sites. Thus, delivering safe and effective tDTLT requires understanding the physics of light propagation in tissue. This study simulates laser light propagation in an anatomically accurate human knee model to assess the light transmittance and light absorption‐driven thermal changes for eight commonly used laser therapy wavelengths (600–1200 nm) at multiple skin‐applied irradiances (W cm −2 ) with continuous wave (CW) exposures. It shows that of the simulated parameters, 2.38 W cm −2 (30 W, 20 mm beam radius) of 1064 nm light generated the least tissue heating −4°C at skin surface, after 30 s of CW irradiation, and the highest overall transmission—approximately 3%, to the innermost muscle tissue.
Publisher: Wiley
Date: 17-09-2014
DOI: 10.1002/CNM.2668
Abstract: Head injuries due to complex blasts are not well examined because of limited published articles on the subject. Previous studies have analyzed head injuries due to impact from a single planar blast wave. Complex or concomitant blasts refer to impacts usually caused by more than a single blast source, whereby the blast waves may impact the head simultaneously or consecutively, depending on the locations and distances of the blast sources from the subject, their blast intensities, the sequence of detonations, as well as the effect of blast wave reflections from rigid walls. It is expected that such scenarios will result in more serious head injuries as compared to impact from a single blast wave due to the larger effective duration of the blast. In this paper, the utilization of a head–helmet model for blast impact analyses in Abaqus TM (Dassault Systemes, Singapore) is demonstrated. The model is validated against studies published in the literature. Results show that the skull is capable of transmitting the blast impact to cause high intracranial pressures (ICPs). In addition, the pressure wave from a frontal blast may enter through the sides of the helmet and wrap around the head to result in a second impact at the rear. This study recommended better protection at the sides and rear of the helmet through the use of foam pads so as to reduce wave entry into the helmet. The consecutive frontal blasts scenario resulted in higher ICPs compared with impact from a single frontal blast. This implied that blast impingement from an immediate subsequent pressure wave would increase severity of brain injury. For the unhelmeted head case, a peak ICP of 330 kPa is registered at the parietal lobe which exceeds the 235 kPa threshold for serious head injuries. The concurrent front and side blasts scenario yielded lower ICPs and skull stresses than the consecutive frontal blasts case. It is also revealed that the additional side blast would only significantly affect ICPs at the temporal and parietal lobes when compared with results from the single frontal blast case. By analyzing the pressure wave flow surrounding the head and correlating them with the consequential evolution of ICP and skull stress, the paper provides insights into the interaction mechanics between the concomitant blast waves and the biological head model. Copyright © 2014 John Wiley & Sons, Ltd.
Publisher: Elsevier BV
Date: 06-2023
Publisher: SAGE Publications
Date: 08-10-2017
Abstract: Blast-induced traumatic brain injury is the most prevalent injury sustained by combat soldiers at the frontline. The current study aims to investigate the effectiveness of composite polycarbonate-aerogel face shields with different configurations in mitigating blast-induced brain injuries. A series of dynamic fluid–structure interaction simulations of a helmeted head subjected to a frontal free field blast was performed, to evaluate the effectiveness of the current conventional polycarbonate face shield and three other composite face shields with different configurations when exposed to a frontal free-field blast. The simulation results demonstrated that the sandwiched structured face shields of polycarbonate and aerogel provided superior blast attenuation than a single-layered polycarbonate face shield. The alternate multi-layered transparent materials of high and low densities provided the best attenuation of blast pressure transmission to the head, with the polycarbonate exterior shell casing contributing to the structural integrity of the face shield, while the lower dense aerogel filler providing high acoustic impedance to blast wave transmission. This study provides further insights on future development and design of personal protective equipment in mitigating blast-induced injuries to the head.
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.JBIOMECH.2010.12.014
Abstract: Aortic dissecting aneurysm is one of the most catastrophic cardiovascular emergencies that carries high mortality. It was pointed out from clinical observations that the aneurysm development is likely to be related to the hemodynamics condition of the dissected aorta. In order to gain more insight on the formation and progression of dissecting aneurysm, hemodynamic parameters including flow pattern, velocity distribution, aortic wall pressure and shear stress, which are difficult to measure in vivo, are evaluated using numerical simulations. Pulsatile blood flow in patient-specific dissecting aneurismal aortas before and after the formation of lumenal aneurysm (pre-aneurysm and post-aneurysm) is investigated by computational fluid dynamics (CFD) simulations. Realistic time-dependent boundary conditions are prescribed at various arteries of the complete aorta models. This study suggests the helical development of false lumen around true lumen may be related to the helical nature of hemodynamic flow in aorta. Narrowing of the aorta is responsible for the massive recirculation in the poststenosis region in the lumenal aneurysm development. High pressure difference of 0.21 kPa between true and false lumens in the pre-aneurismal aorta infers the possible lumenal aneurysm site in the descending aorta. It is also found that relatively high time-averaged wall shear stress (in the range of 4-8 kPa) may be associated with tear initiation and propagation. CFD modeling assists in medical planning by providing blood flow patterns, wall pressure and wall shear stress. This helps to understand various phenomena in the development of dissecting aneurysm.
Publisher: Wiley
Date: 08-09-2023
Abstract: This study aims to explore the feasibility of using a structure inspired by the features of horsetail and human spine as the potential helmet liner, targeting at mitigation of acceleration‐induced injuries, which includes rotational acceleration that focused by many researchers due to its dominance in causing severe brain injuries when cycling crashes happen. Evaluation of the compressive and shear performance of the new horsetail liner structure, as well as the material characterization of expanded polystyrene foam (EPS) and thermoplastic polyurethane (TPU), have been conducted using both experimental and numerical means. In order to come up with the best design configuration of the horsetail liner structure, parametric study was also conducted to investigate the effect of in idual geometrical variables in the design. The results showed that the optimal bio‐inspired horsetail structure was capable in reducing kinetic energy induced by both linear and rotational accelerations, demonstrating a potential application of this structure as a helmet liner. Suggestions on how to implement this horsetail liner structure into an actual commercial helmet were also made in this study. This article is protected by copyright. All rights reserved.
Publisher: Wiley
Date: 11-2019
DOI: 10.1002/JOR.24152
Abstract: Rotator cuff tears are known to affect clinical outcome of reverse total shoulder arthroplasty (RSA). This study aimed to use computational modelling to quantify the effect of rotator cuff tear severity on muscle and joint forces after RSA, as well as stresses at the glenosphere, base-plate, fixation screws, scapula, and humeral components. A multi-body musculoskeletal model of the glenohumeral joint was developed comprising the scapula, humerus and nine major upper limb muscles. Simulations of abduction and flexion after RSA were performed in the case of the intact rotator cuff and tears to (i) supraspinatus (ii) supraspinatus and infraspinatus, and (iii) supraspinatus, infraspinatus and subscapularis. The intact and supraspinatus deficient rotator cuff resulted in the largest calculated muscle forces, glenohumeral joint contact forces and implant stresses. Peak glenohumeral joint forces during flexion were lower than those during abduction in all cases however, substantially more posterior joint shear force was generated during flexion than abduction. A tear involving the supraspinatus and infraspinatus reduced glenohumeral joint forces by a factor of 8.7 during abduction (603.1 N) and 7.1 during flexion (520.7 N) compared to those in the supraspinatus deficient shoulder. RSA with an intact or supraspinatus deficient rotator cuff produces large glenohumeral joint forces that may increase base-plate failure risk, particularly during flexion when posterior shear forces are largest. Infraspinatus tears after RSA greatly reduce glenohumeral joint compression and may ultimately reduce joint stability. Future research ought to focus on experimental validation of subject-specific muscle recruitment strategies and joint loading after RSA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Publisher: Oxford University Press (OUP)
Date: 05-07-2012
DOI: 10.1093/EJCTS/EZS388
Abstract: Cardiovascular diseases, such as atherosclerosis and aneurysm, are closely associated with haemodynamic factors that are governed by luminal geometry. The present work aimed to study the effect of geometrical variation of aging aortas on haemodynamics. Six aged subjects with intricate geometrical features, such as bulging or twisted supra-aortic arteries, sharply curved arch and double-curved descending aorta, were chosen from our medical database. These six geometrically variant aortas were reconstructed and the pulsatile nature of the blood flow of these subject-specific aorta models investigated using computational fluid dynamics simulations. Realistic time-dependent boundary conditions are prescribed for various arteries of the aorta models. This study suggests that haemodynamics in the human aorta is highly dependent on geometrical features. The positioning and contouring of the supra-aortic arteries may be associated with the skewness of velocity profiles. The flow profiles in the aortic arch or bends are generally skewed towards the inner curvature wall and this skewness may give rise to the formation of secondary flow in the inner curvature wall of the distal arch. The degree of vorticity in the distal aortic arch is found to be related to the arch curvature. The helical nature of aortic haemodynamics is predominant in the systole phrase when it begins with a left-handed rotation and then vanishes in the ascending aorta, whereas a right-handed rotation persists in the distal aortic arch. Lower wall shear stress is also found in the ascending regions where secondary flow is present. The aorta with an irregular contour and large degree of curvature at its arch favours the development of the intra-aortic secondary flow that subsequently relates to the pathogenesis of atheroma. The present study identifies the general trend of haemodynamic behaviours associated with various local geometrical features. Combining the knowledge of the correlation between haemodynamics and the underlying risks in the development of cardiovascular diseases, our study hopes to provide a better understanding of the relationship between aortic morphology and developing pathobiology of cardiovascular diseases. As such, early medical planning as well as surgical interventions can be designed to retard or prevent the development of cardiovascular diseases.
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 03-2023
Publisher: Springer Science and Business Media LLC
Date: 23-07-2019
DOI: 10.1007/S10439-019-02316-Y
Abstract: The ability to rapidly detect localised fractures of cortical and/or trabecular bone sustained by the vertebral body would enhance the analysis of vertebral fracture initiation and propagation during dynamic loading. In this study, high rate axial compression tests were performed on twenty sets of three-vertebra lumbar spine specimens. Acoustic Emission (AE) sensor measurements of sound wave pressure were used to classify isolated trabecular fractures and severe compressive fractures of vertebral body cortical and trabecular bone. Fracture detection using standard AE parameters was compared to that of traditional mechanical parameters obtained from load cell and displacement readings. Results indicated that the AE parameters achieved slightly enhanced classification of isolated trabecular fractures, whereas the mechanical parameters better identified combined fractures of cortical and trabecular bone. These findings demonstrate that AE may be used to promptly and accurately identify localised fractures of trabecular bone, whereas more extensive fractures of the vertebral body are best identified by load cell readings due to the considerable loss in compressive resistance. The discrimination thresholds corresponding to the AE parameters were based on calibrated measurements of AE wave pressure and may ultimately be used to examine the onset and progression of vertebral fracture in other loading scenarios.
Publisher: Elsevier BV
Date: 11-2021
Publisher: Springer International Publishing
Date: 2014
Publisher: Wiley
Date: 09-12-2015
Abstract: In this paper, two cadmium(II) coordination polymers [Cd(sdb)(bib)] n ( 1 ) and {[Cd 2 (pda) 2 (bib) 2 ] · 0.5H 2 O} n ( 2 ) [H 2 sdb = 4,4′‐sulfonyl‐dicarboxylic acid, H 2 pda = 1,3‐phenylenediacetic acid, and bib = 1,4‐bis(1‐imidazolyl) benzene] were synthesized and characterized by hydrothermal methods. Complex 1 displays a 3,5‐connected topological net and complex 2 shows a 4‐connected non‐interpenetrated pcu framework. Furthermore, the luminescent properties for complexes 1 and 2 were investigated.
Publisher: BMJ
Date: 02-09-2012
DOI: 10.1136/BJOPHTHALMOL-2011-300228
Abstract: This study aimed to provide an objective assessment of the effects on the aqueous outflow rate of various geometries of the scleral flap and sclerostomy created in trabeculectomy. Computer-based models and simulations of this surgical procedure were used to investigate the relative effects of various shapes and dimensions of scleral flap and sclerostomy on the aqueous outflow. In these computer simulations, increasing scleral flap size was found to be associated with an increase of 48.55% in aqueous egress. In addition, a square scleral flap increased the aqueous drainage by 36.26% compared with a triangular flap of equivalent flap area. Surprisingly, our simulation results showed that a smaller semicircular sclerostomy improved aqueous drainage by up to 33.00%, while a semicircular sclerostomy, compared with a circular sclerostomy, led to a further 6.16% increase in aqueous outflow. Decreasing flap thickness beyond half-thickness caused an additional increase in aqueous outflow. However, clinically the flap should not be thinner than half the thickness of the sclera as this may result in hypotony. These simulations indicate that the optimal flow rate through operation site will be achieved in trabeculectomy using a square scleral flap with a large flap-to-sclerostomy ratio.
Publisher: MDPI AG
Date: 10-01-2022
DOI: 10.3390/BIOENGINEERING9010026
Abstract: Computational modelling of damage and rupture of non-connective and connective soft tissues due to pathological and supra-physiological mechanisms is vital in the fundamental understanding of failures. Recent advancements in soft tissue damage models play an essential role in developing artificial tissues, medical devices/implants, and surgical intervention practices. The current article reviews the recently developed damage models and rupture models that considered the microstructure of the tissues. Earlier review works presented damage and rupture separately, wherein this work reviews both damage and rupture in soft tissues. Wherein the present article provides a detailed review of various models on the damage evolution and tear in soft tissues focusing on key conceptual ideas, advantages, limitations, and challenges. Some key challenges of damage and rupture models are outlined in the article, which helps extend the present damage and rupture models to various soft tissues.
Publisher: Georg Thieme Verlag KG
Date: 18-11-2015
Abstract: This study proposes that the bony anatomy of the human nose and masonry structure of the Gothic cathedral are geometrically similar, and have common fracture patterns. We also aim to correlate the fracture patterns observed in patients' midface structures with those seen in the Gothic cathedral using computational approach. CT scans of 33 patients with facial fractures were examined and compared with computer simulations of both the Gothic cathedral and human nose. Three similar patterns were found: (1) Cracks of the nasal arch with crumpling of the vertical buttresses akin to the damage seen during minor earthquakes (2) lateral deviation of the central nasal arch and collapse of the vertical buttresses akin to those due to lateral forces from wind and in major earthquakes and (3) Central arch collapse seen as a result of collapse under excessive dead weight. Interestingly, the finding of occult nasal and septal fractures in the mandible fractures with absence of direct nasal trauma highlights the possibility of transmission of forces from the foundation to the arch leading to structural failure. It was also found that the structural buttresses of the Gothic cathedral delineate the vertical buttresses in the human midface structure. These morphologic similarities between the human nose and Gothic cathedral will serve as a basis to study the biomechanics of nasal fractures. Identification of structural buttresses in a skeletal structure has important implications for reconstruction as reestablishment of structural continuity restores normal anatomy and architectural stability of the human midface structure.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 09-2023
Publisher: Routledge
Date: 19-06-2015
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 12-2012
Publisher: Informa UK Limited
Date: 10-09-2018
DOI: 10.1080/10255842.2018.1511775
Abstract: In the present study, the free fall impact test in accordance with the EN1078 standard for certification of bicycle helmets is replicated using numerical simulations. The impact scenario is simulated using an experimentally validated, patient-specific head model equipped with and without a bicycle helmet. Head accelerations and intracranial biomechanical injury metrics during the impacts are recorded. It is demonstrated that wearing the bicycle helmet during the impact reduces biomechanical injury metrics, with the biggest reduction seen in the metric for skull fracture.
Publisher: Springer Science and Business Media LLC
Date: 13-07-2016
DOI: 10.1007/S11517-016-1536-3
Abstract: The current study aims to investigate the effectiveness of two different designs of helmet interior cushion, (Helmet 1: strap-netting Helmet 2: Oregon Aero foam-padding), and the effect of the impact directions on the helmeted head during ballistic impact. Series of ballistic impact simulations (frontal, lateral, rear, and top) of a full-metal-jacketed bullet were performed on a validated finite element head model equipped with the two helmets, to assess the severity of head injuries sustained in ballistic impacts using both head kinematics and biomechanical metrics. Benchmarking with experimental ventricular and intracranial pressures showed that there is good agreement between the simulations and experiments. In terms of extracranial injuries, top impact had the highest skull stress, still without fracturing the skull. In regard to intracranial injuries, both the lateral and rear impacts generally gave the highest principal strains as well as highest shear strains, which exceed the injury thresholds. Off-cushion impacts were found to be at higher risk of intracranial injuries. The study also showed that the Oregon Aero foam pads helped to reduce impact forces. It also suggested that more padding inserts of smaller size may offer better protection. This provides some insights on future's helmet design against ballistic threats.
Publisher: MDPI AG
Date: 15-05-2023
DOI: 10.3390/PR11051506
Abstract: Due to growing concern over environmental impacts and the pressure to lower carbon footprints in the metals industry, hydrogen (H2) has gained attention as a promising alternative for the replacement of carbon as a reductant and fuel. This paper evaluates the potential use of hydrogen as an energy source and reducing agent during the processing of waste printed circuit boards (waste PCBs) from e-waste through black copper smelting. The effect of the use of carbon and hydrogen during the reduction–oxidation process was analysed and compared from the perspective of thermodynamics and heat balance. The thermodynamic analyses of waste-PCB processing were carried out using the FactSage thermochemical package for the smelting process at temperatures from 1473 K to 1673 K (1200–1400 °C). The results show that the CO2 emissions can be reduced by 73% when hydrogen is used as the reducing agent. A minimum of 10 wt% of waste PCBs in the feed material can be used to replace the necessary carbon to supply heat for the reduction process. The addition of waste PCBs can increase the volume of slag and affect the composition of the off gas.
Publisher: MDPI AG
Date: 03-11-2021
DOI: 10.3390/BIOENGINEERING8110173
Abstract: In this study, a novel expandable bicycle helmet, which integrates an airbag system into the conventional helmet design, was proposed to explore the potential synergetic effect of an expandable airbag and a standard commuter-type EPS helmet. The traumatic brain injury mitigation performance of the proposed expandable helmet was evaluated against that of a typical traditional bicycle helmet. A series of dynamic impact simulations on both a helmeted headform and a representative human head with different configurations were carried out in accordance with the widely recognised international bicycle helmet test standards. The impact simulations were initially performed on a ballast headform for validation and benchmarking purposes, while the subsequent ones on a biofidelic human head model were used for assessing any potential intracranial injury. It was found that the proposed expandable helmet performed admirably better when compared to a conventional helmet design—showing improvements in impact energy attenuation, as well as kinematic and biometric injury risk reduction. More importantly, this expandable helmet concept, integrating the airbag system in the conventional design, offers adequate protection to the cyclist in the unlikely case of airbag deployment failure.
Publisher: MDPI AG
Date: 27-06-2023
DOI: 10.3390/BIOENGINEERING10070773
Abstract: The aim of this review article is to appraise the design and functionality of above-knee prosthetic legs. So far, various transfemoral prosthetic legs are found to offer a stable gait to utees but are limited to laboratories. The commercially available prosthetic legs are not reliable and comfortable enough to satisfy utees. There is a dire need for creating a powered prosthetic knee joint that could address utees’ requirements. To pinpoint the gap in transfemoral prosthetic legs, prosthetic knee unit model designs, control frameworks, kinematics, and gait evaluations are concentrated. Ambulation exercises, ground-level walking, running, and slope walking are considered to help identify research gaps and areas where existing prostheses can be ameliorated. The results show that above-knee utees can more effectively manage their issues with the aid of an active prosthesis, capable of reliable gait. To accomplish the necessary control, closed loop controllers and volitional control are integral parts. Future studies should consider designing a transfemoral electromechanical prosthesis based on electromyographic (EMG) signals to better predict the utee’s intent and control in accordance with that intent.
Publisher: SAGE Publications
Date: 06-2012
Abstract: Complex 3-D defects of the facial skeleton are difficult to reconstruct with freehand carving of autogenous bone grafts. Onlay bone grafts are hard to carve and are associated with imprecise graft-bone interface contact and bony resorption. Autologous cartilage is well established in ear reconstruction as it is easy to carve and is associated with minimal resorption. In the present study, we aimed to reconstruct the hypoplastic orbitozygomatic region in a patient with left hemifacial microsomia using computer-aided design and rapid prototyping to facilitate costal cartilage carving and grafting. A three-step process of (1) 3-D reconstruction of the computed tomographic image, (2) mirroring the facial skeleton, and (3) modeling and rapid prototyping of the left orbitozygomaticomalar region and reconstruction template was performed. The template aided in donor site selection and extracorporeal contouring of the rib cartilage graft to allow for an accurate fit of the graft to the bony model prior to final fixation in the patient. We are able to refine the existing computer-aided design and rapid prototyping methods to allow for extracorporeal contouring of grafts and present rib cartilage as a good alternative to bone for autologous reconstruction.
Publisher: SAGE Publications
Date: 06-01-2020
Abstract: In real world applications, buried pipelines span across great lengths. It is inevitable that certain sections of a buried pipeline experience external loads in addition to top soil overburden, such as weights of aboveground buildings and traffic loads located directly above these sections. The present study investigated the effects of overburden soil, pipe internal pressurization, and traffic loads on fiber-reinforced plastic pipelines at various pipe sections with particular emphasis on pipe joints using finite element method. This study includes realistic modeling of traffic loading on service road running across a buried pipeline system, consisting of straight, bent, and joint sections. Our results also revealed that surcharge loading might not be a predominant factor in pipe failure or leakage issues as compared to the cyclic pipe internal pressurization. Moreover, it was also confirmed in our study that the pipe joint remained as the most critical region for pipe failure or leakage issues.
Publisher: Elsevier BV
Date: 03-2017
Publisher: JVE International Ltd.
Date: 15-11-2016
Abstract: The human head-neck is the most complex structure in the human body and its behavior under vibration remain poorly understood. Therefore, a comprehensive theoretical or experimental analysis is needed. This study is mainly based on an available finite element human head-neck complex and concentrates on its modal and dynamic responses. Resonance frequencies and responses of the human head-neck complex’s finite element model in impact simulations have been analyzed. These dynamic responses show a very good agreement with the previous studies. The fundamental frequency of modal analysis of finite element model is 35.25 Hz which is reasonably close to existing literatures. However, our modal dynamic analysis of an elaborated human head-neck complex introduces supplementary dynamic responses like nasal sideward cartilages’ “flipping” modes and the mandible’s “mastication” modes. Modal validation is performed which indicates a requirement for elaborated modeling to make out all the extra resonance frequencies. Moreover, the influence of d ing factor on biomechanical response or natural frequencies is also investigated. It can be found that d ing factor has got an inverse proportionality between d ing factor effect on natural frequency and that on biomechanical responses. This demonstrates the significance of identification of the suitable d ing factor evaluating biomechanical response in modal dynamic analysis and validation.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.BJPS.2018.05.026
Abstract: The Nuss procedure is the most minimally invasive and commonly used surgical correction for pectus excavatum (PE) by using a prebent pectus bar to elevate the deformed chest wall. However, there are some complications associated with this procedure such as postoperative pain as well as surgical uncertainties because of human judgment. It is therefore important to understand the biomechanical effect of the pectus bar on PE thoraces undergoing an operation to alleviate the postoperative pain as well as to improve surgical outcome. The current study incorporated the finite element method (FEM) to simulate the entire Nuss procedure including the flipping process of the pectus bar on a preoperative PE patient-specific thorax model, in conjunction with comparison against the postoperative CT scans. The mid-sagittal sternovertebral elevation was found to be within 5.32 mm, whereas the transverse sternal deviations ranged from 1.59 to 3.02 mm. The average discrepancy between the predicted contour and postoperative CT contour was approximately 3%. On a different note, the stress and strain distributions largely concurred with reported findings. High bilateral stress was seen to occur at the back of ribs near the vertebral column, and particularly over the second to fifth ribs, whereas the greatest strain was found to be confined to the regions of costal cartilages. It is evident that the FEM is a feasible and robust approach in predicting the outcome of the mechanical surgical procedure. This contributes to the future development of a predictive tool incorporated in surgical planning to enhance surgical management of PE.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Wiley
Date: 05-11-2013
DOI: 10.1002/CNM.2609
Abstract: Head injury, being one of the main causes of death or permanent disability, continues to remain a major health problem with significant socioeconomic costs. Numerical simulations using the FEM offer a cost-effective method and alternative to experimental methods in the biomechanical studies of head injury. The present study aimed to develop two realistic subject-specific FEMs of the human head with detailed anatomical features from medical images (Model 1: without soft tissue and Model 2: with soft tissue and differentiation of white and gray matters) and to validate them against the intracranial pressure (ICP) and relative intracranial motion data of the three cadaver experimental tests. In general, both the simulated results were in reasonably good agreement with the experimental measured ICP and relative displacements, despite slight discrepancy in a few neutral density targets markers. Sensitivity analysis showed some variations in the brain's relative motion to the material properties or marker's location. The addition of soft tissue in Model 2 helped to d out the oscillations of the model response. It was also found that, despite the fundamental anatomical differences between the two models, there existed little evident differences in the predicted ICP and relative displacements of the two models. This indicated that the advancements on the details of the extracranial features would not improve the model's predicting capabilities of brain injury.
Publisher: Elsevier BV
Date: 10-2022
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/408278
Abstract: This study is aimed at developing a high quality, validated finite element (FE) human head model for traumatic brain injuries (TBI) prediction and prevention during vehicle collisions. The geometry of the FE model was based on computed tomography (CT) and magnetic resonance imaging (MRI) scans of a volunteer close to the anthropometry of a 50th percentile male. The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The cerebrospinal fluid (CSF) was simulated explicitly as a hydrostatic fluid by using a surface-based fluid modeling method. The model was validated in the loading condition observed in frontal impact vehicle collision. These validations include the intracranial pressure (ICP), brain motion, impact force and intracranial acceleration response, maximum von Mises stress in the brain, and maximum principal stress in the skull. Overall results obtained in the validation indicated improved biofidelity relative to previous FE models, and the change in the maximum von Mises in the brain is mainly caused by the improvement of the CSF simulation. The model may be used for improving the current injury criteria of the brain and anthropometric test devices.
Publisher: The Royal Society
Date: 2018
Abstract: Low back pain is a major cause of disability and requires the development of new devices to treat pathologies and improve prognosis following surgery. Understanding the effects of new devices on the biomechanics of the spine is crucial in the development of new effective and functional devices. The aim of this study was to develop a preliminary parametric, scalable and anatomically accurate finite-element model of the lumbar spine allowing for the evaluation of the performance of spinal devices. The principal anatomical surfaces of the lumbar spine were first identified, and then accurately fitted from a previous model supplied by S14 Implants (Bordeaux, France). Finally, the reconstructed model was defined according to 17 parameters which are used to scale the model according to patient dimensions. The developed model, available as a toolbox named the lumbar model generator, enables generating a population of models using subject-specific dimensions obtained from data scans or averaged dimensions evaluated from the correlation analysis. This toolbox allows patient-specific assessment, taking into account in idual morphological variation. The models have applications in the design process of new devices, evaluating the biomechanics of the spine and helping clinicians when deciding on treatment strategies.
Publisher: Wiley
Date: 31-05-2017
DOI: 10.1002/CNM.2884
Abstract: Blast-induced traumatic brain injury has been on the rise in recent years because of the increasing use of improvised explosive devices in conflict zones. Our study investigates the response of a helmeted human head subjected to a blast of 1 atm peak overpressure, for cases with and without a standard polycarbonate (PC) face shield and for face shields comprising of composite PC and aerogel materials and with lateral edge extension. The novel introduction of aerogel into the laminate face shield is explored and its wave-structure interaction mechanics and performance in blast mitigation is analysed. Our numerical results show that the face shield prevented direct exposure of the blast wave to the face and help delays the transmission of the blast to reduce the intracranial pressures (ICPs) at the parietal lobe. However, the blast wave can diffract and enter the midface region at the bottom and side edges of the face shield, resulting in traumatic brain injury. This suggests that the bottom and sides of the face shield are important regions to focus on to reduce wave ingress. The laminated PC/aerogel/PC face shield yielded higher peak positive and negative ICPs at the frontal lobe, than the original PC one. For the occipital and temporal brain regions, the laminated face shield performed better than the original. The composite face shield with extended edges reduced ICP at the temporal lobe but increases ICP significantly at the parietal lobe, which suggests that a greater coverage may not lead to better mitigating effects.
Start Date: 12-2021
End Date: 11-2024
Amount: $392,801.00
Funder: Australian Research Council
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