Displaying publications 81 - 100 of 139 in total

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  1. Khoo W, Chung SM, Lim SC, Low CY, Shapiro JM, Koh CT
    Data Brief, 2019 Dec;27:104718.
    PMID: 31763388 DOI: 10.1016/j.dib.2019.104718
    Data in this article are supplementary to the corresponding research article [1]. Morphological features of homogeneous and graded nanofibrous electrospun gelatin scaffolds were observed using scanning electron microscopy. Microstructural properties including fiber diameter and pore size were determined via image analysis, using ImageJ. Uniaxial tensile and fracture tests were performed on both homogeneous and graded scaffolds using a universal testing machine. Stress-strain curves of all scaffolds are presented. Computing software, MATLAB, was used to design fibrous networks with thickness-dependent density and alignment gradients (DAG). Finite element analysis software, Abaqus, was used to determine the effect of the number of layers on the fracture properties of DAG multilayer scaffolds.
    Matched MeSH terms: Finite Element Analysis
  2. Kho ASK, Foo JJ, Ooi ET, Ooi EH
    Comput Methods Programs Biomed, 2020 Feb;184:105289.
    PMID: 31891903 DOI: 10.1016/j.cmpb.2019.105289
    BACKGROUND AND OBJECTIVE: The majority of the studies on radiofrequency ablation (RFA) have focused on enlarging the size of the coagulation zone. An aspect that is crucial but often overlooked is the shape of the coagulation zone. The shape is crucial because the majority of tumours are irregularly-shaped. In this paper, the ability to manipulate the shape of the coagulation zone following saline-infused RFA by altering the location of saline infusion is explored.

    METHODS: A 3D model of the liver tissue was developed. Saline infusion was described using the dual porosity model, while RFA was described using the electrostatic and bioheat transfer equations. Three infusion locations were investigated, namely at the proximal end, the middle and the distal end of the electrode. Investigations were carried out numerically using the finite element method.

    RESULTS: Results indicated that greater thermal coagulation was found in the region of tissue occupied by the saline bolus. Infusion at the middle of the electrode led to the largest coagulation volume followed by infusion at the proximal and distal ends. It was also found that the ability to delay roll-off, as commonly associated with saline-infused RFA, was true only for the case when infusion is carried out at the middle. When infused at the proximal and distal ends, the occurrence of roll-off was advanced. This may be due to the rapid and more intense heating experienced by the tissue when infusion is carried out at the electrode ends where Joule heating is dominant.

    CONCLUSION: Altering the location of saline infusion can influence the shape of the coagulation zone following saline-infused RFA. The ability to 'shift' the coagulation zone to a desired location opens up great opportunities for the development of more precise saline-infused RFA treatment that targets specific regions within the tissue.

    Matched MeSH terms: Finite Element Analysis
  3. Khalili AA, Ahmad MR
    Int J Mol Sci, 2015;16(11):26770-85.
    PMID: 26569218 DOI: 10.3390/ijms161125987
    Single-cell analysis has become the interest of a wide range of biological and biomedical engineering research. It could provide precise information on individual cells, leading to important knowledge regarding human diseases. To perform single-cell analysis, it is crucial to isolate the individual cells before further manipulation is carried out. Recently, microfluidic biochips have been widely used for cell trapping and single cell analysis, such as mechanical and electrical detection. This work focuses on developing a finite element simulation model of single-cell trapping system for any types of cells or particles based on the hydrodynamic flow resistance (Rh) manipulations in the main channel and trap channel to achieve successful trapping. Analysis is carried out using finite element ABAQUS-FEA™ software. A guideline to design and optimize single-cell trapping model is proposed and the example of a thorough optimization analysis is carried out using a yeast cell model. The results show the finite element model is able to trap a single cell inside the fluidic environment. Fluid's velocity profile and streamline plots for successful and unsuccessful single yeast cell trapping are presented according to the hydrodynamic concept. The single-cell trapping model can be a significant important guideline in designing a new chip for biomedical applications.
    Matched MeSH terms: Finite Element Analysis
  4. Kashyzadeh KR, Rahimian Koloor SS, Omidi Bidgoli M, Petrů M, Amiri Asfarjani A
    Polymers (Basel), 2021 Feb 03;13(4).
    PMID: 33546387 DOI: 10.3390/polym13040483
    The main purpose of this research is to design a high-fatigue performance hoop wrapped compressed natural gas (CNG) composite cylinder. To this end, an optimization algorithm was presented as a combination of finite element simulation (FES) and response surface analysis (RSA). The geometrical model was prepared as a variable wall-thickness following the experimental measurements. Next, transient dynamic analysis was performed subjected to the refueling process, including the minimum and maximum internal pressures of 20 and 200 bar, respectively. The time histories of stress tensor components were extracted in the critical region. Furthermore, RSA was utilized to investigate the interaction effects of various polymer composite shell manufacturing process parameters (thickness and fiber angle) on the fatigue life of polymer composite CNG pressure tank (type-4). In the optimization procedure, four parameters including wall-thickness of the composite shell in three different sections of the CNG tank and fiber angle were considered as input variables. In addition, the maximum principal stress of the component was considered as the objective function. Eventually, the fatigue life of the polymer composite tank was calculated using stress-based failure criterion. The results indicated that the proposed new design (applying optimal parameters) leads to improve the fatigue life of the polymer composite tank with polyethylene liner about 2.4 times in comparison with the initial design.
    Matched MeSH terms: Finite Element Analysis
  5. Karimzadeh A, R Koloor SS, Ayatollahi MR, Bushroa AR, Yahya MY
    Sci Rep, 2019 10 31;9(1):15763.
    PMID: 31673118 DOI: 10.1038/s41598-019-51904-4
    This study investigates the capacity of the nano-indentation method in the mechanical characterization of a heterogeneous dental restorative nanocomposite using experimental and computational approaches. In this respect, Filtek Z350 XT was selected as a nano-particle reinforced polymer nanocomposite with a specific range of the particle size (50 nm to 4 µm), within the range of indenter contact area of the nano-indentation experiment. A Sufficient number of nano-indentation tests were performed in various locations of the nanocomposite to extract the hardness and elastic modulus properties. A hybrid computational-experimental approach was developed to examine the extracted properties by linking the internal behaviour and the global response of the nanocomposite. In the computational part, several representative models of the nanocomposite were created in a finite element environment to simulate the mechanism of elastic-plastic deformation of the nanocomposite under Berkovich indenter. Dispersed values of hardness and elastic modulus were obtained through the experiment with 26.8 and 48.5 percent average errors, respectively, in comparison to the nanocomposite properties, respectively. A disordered shape was predicted for plastic deformation of the equilateral indentation mark, representing the interaction of the particles and matrix, which caused the experiment results reflect the local behaviour of the nanocomposite instead of the real material properties.
    Matched MeSH terms: Finite Element Analysis
  6. Kadir MR, Syahrom A, Ochsner A
    Med Biol Eng Comput, 2010 May;48(5):497-505.
    PMID: 20224954 DOI: 10.1007/s11517-010-0593-2
    Human bones can be categorised into one of two types--the compact cortical and the porous cancellous. Whilst the cortical is a solid structure macroscopically, the structure of cancellous bone is highly complex with plate-like and strut-like structures of various sizes and shapes depending on the anatomical site. Reconstructing the actual structure of cancellous bone for defect filling is highly unfeasible. However, the complex structure can be simplified into an idealised structure with similar properties. In this study, two idealised architectures were developed based on morphological indices of cancellous bone: the tetrakaidecahedral and the prismatic. The two architectures were further subdivided into two types of microstructure, the first consists of struts only and the second consists of a combination of plates and struts. The microstructures were transformed into finite element models and displacement boundary condition was applied to all four idealised cancellous models with periodic boundary conditions. Eight unit cells extracted from the actual cancellous bone obtained from micro-computed tomography were also analysed with the same boundary conditions. Young's modulus values were calculated and comparison was made between the idealised and real cancellous structures. Results showed that all models with a combination of plates and struts have higher rigidity compared to the one with struts only. Values of Young's modulus from eight unit cells of cancellous bone varied from 42 to 479 MPa with an average of 234 MPa. The prismatic architecture with plates and rods closely resemble the average stiffness of a unit cell of cancellous bone.
    Matched MeSH terms: Finite Element Analysis
  7. Jiading Wang, Tianfeng Gu, Jianbin Wang, Yuanjun Xu, Peng Chen, Muhammad Aqeel Ashraf
    Sains Malaysiana, 2017;46:2049-2059.
    The development degree of fissure water in underground rock is a great trouble to the construction of railway tunnel, which will cause a series of environmental geological problems. Take the surrounding rock-section of the typical red clay in Lvliang-Mt. railway tunnel below the underground water level as an example, several aspects about the red clay surrounding rock will be researched, including pore water pressure, volume moisture content, stress of surrounding rock, vault subsidence and horizontal convergence through the field monitoring. Taking into account the importance of railway tunnel engineering, the large shear test of red clay was carried out at the construction site specially and the reliable situ shear strength parameters of surrounding rock will be obtained. These investigations and field tests helped to do a series of work: Three dimensional finite element numerical model of railway tunnel will be established, the deformation law of the red clay surrounding rock will be investigated, respectively, for the water-stress coupling effect and without considering it, the variation of the pore water pressure during excavation, the influence degree about the displacement field and stress field of water-stress coupling on red clay-rock will be discussed and the mechanism of the surrounding rock deformation will be submitted. Finally, the paper puts forward the feasible drainage scheme of the surrounding rock and the tunnel cathode. The geological environment safety of tunnel construction is effectively protected.
    Matched MeSH terms: Finite Element Analysis
  8. Jamaluddin Mahmud, Ahmad Kamil Hussain, Norzihan Rahimi, Mastura Abdul Rahim
    MyJurnal
    The finite element method is gaining acceptance in predicting mechanical response of various loading configurations and material orientations for failure analysis of composite laminates. Both fabrication of laminate samples and experimental procedures are often expensive and time consuming, and hence impractical, especially during the initial design stage. Finite element analyses require minimal amounts of input data, and the resulting stress and strain distributions can be determined throughout each individual ply. Using ANSYSTM, a commercially available finite element package, failure loads were predicted by simulating a uniaxial tensile loading on HTS40/977-2 Carbon/Epoxy composite with [+/-4512s lamination scheme. Two built-in failure theories in ANSYSTM features, viz., Maximum Stress and Tsai-Wu were applied in the simulation. The stress-strain and load-extension curves for both actual testing and FEA were then compared and the results are in good agreement. This paper is intended for researchers who have used or are considering using ANSYSTM for the prediction of failure in composite materials.
    Matched MeSH terms: Finite Element Analysis
  9. Jalal Abdullah S, Shaikh Mohammed J
    Disabil Rehabil Assist Technol, 2019 11;14(8):849-858.
    PMID: 30556753 DOI: 10.1080/17483107.2018.1539130
    Purpose: Some wheelchair users continue to struggle in maneuvering a wheelchair and navigating through manual doors. Several smart wheelchairs and robotic manipulators were developed to minimize such challenges facing disabled people. Disappointingly, a majority of these high-tech solutions are restricted to laboratories and are not extensively available as commercial products. Previously, a low-tech wheelchair accessory (arc-shaped with many wheels) for pushing doors was modelled and simulated. This work demonstrates the fabrication and testing of the first-generation prototype of the accessory.Materials and methods: The accessory has side portions with a straight arrangement of wheels and a front portion with a straight-arc-straight arrangement of wheels. The accessory was fabricated using conventional manufacturing, off-the-shelf components, and 3D printed ABS fasteners. Stress analysis simulations were done for the fasteners that attach the front accessory to the wheelchair frame. The proof-of-concept of the prototype installed onto a powered wheelchair was tested with a door and an obstacle, each with ∼50 N resistance force.Results: Prototype tests demonstrate the ability of the accessory along with the mechanical robustness of the 3D printed fasteners to push open doors allowing easy navigation through doors and to push/glide against obstacles. The accessory is foldable and detachable.Conclusion: The low-cost of the accessory makes it affordable to many users intending to improve their quality of life. The current study provides an engineering perspective of the accessory, and a clinical perspective is crucial. Other potential applications of the wheelchair accessory include use with scooters, walkers and stretchers.Implications for rehabilitationLow-cost, low-tech accessory is foldable and detachable.Accessory is effective for pushing doors and pushing/gliding against obstacles.Protective nature of the front accessory could prove highly beneficial to some wheelchair users.
    Matched MeSH terms: Finite Element Analysis
  10. Jain P, Sing Ngie DC, Lim SF, Lim BH
    Int J Artif Organs, 2020 Oct 13.
    PMID: 33045876 DOI: 10.1177/0391398820964483
    Pedicular arthrodesis is the traditional procedure in terms of increase in the biomechanical stability with higher fixation rate. The current work aims to identify the effect of three spinal pedicle screws considering cortical and cancellous degeneracy condition. Lumbar section L2-L3 is utilized and various load and moment conditions were applied to depict the various biomechanical parameters for selection of suitable screw. Three dimensional model is considered in finite element analysis to identify the various responses of pedicle screw at bone screw juncture. Computed tomography (CT) images of a healthy male were considered to generate the finite element vertebral model. Generated intact model was further utilized to develop the other implanted models of degenerated cortical and cancellous bone models. The three fused instrumented models with different cortical and cancellous degeneracy conditions were analyzed in finite element analysis. The results were obtained as stress pattern at bone screw boundary and intervertebral disc stress. FE simulated results represents significant changes in the von Mises stress due to various load and moment conditions on degenerated bones during different body movement conditions. Results have shown that among all pedicle screws, the 6.0 mm diameter screw reflects very less stress values at the juncture. Multiple results on biomechanical aspects obtained during the FE study can be considered to design a new stabilization device and may be helpful to plan surgery of critical sections.
    Matched MeSH terms: Finite Element Analysis
  11. Jahanshahi P, Ghomeishi M, Adikan FR
    ScientificWorldJournal, 2014;2014:503749.
    PMID: 24616635 DOI: 10.1155/2014/503749
    The most common permittivity function models are compared and identifying the best model for further studies is desired. For this study, simulations using several different models and an analytical analysis on a practical surface Plasmon structure were done with an accuracy of ∼ 94.4% with respect to experimental data. Finite element method, combined with dielectric properties extracted from the Brendel-Bormann function model, was utilized, the latter being chosen from a comparative study on four available models.
    Matched MeSH terms: Finite Element Analysis
  12. Jaafar, M.S., Wong, N.J., Noorzaei, J., Thanoon, W.A.
    MyJurnal
    This study presents an efficient finite element analysis technique which shows great versatility in
    modelling of precast composite flooring system subjected to static loadings. The method incorporates sliding and opening in the analysis of composite structures using the interface element which was specifically designed to simulate the actual behaviour at the interfaces between contacting materials. A three-dimensional finite element model of the precast composite slab which exhibits discontinuous behaviour was performed to demonstrate the potential and applicability of the proposed method of analysis. The results of the analysis demonstrate that the overall response of a discontinuous system to external loading is significantly affected by the bonding condition at the interfaces between the contacting materials.
    Matched MeSH terms: Finite Element Analysis
  13. Ismail, A.Y., Noerpamoengkas, A., Zakaria, S.I.F.S.
    MyJurnal
    In this paper, an extensive work on the natural frequency of perforated plate has
    been made by introducing micro-holes on the plate. The micro-holes, which is known
    to have a remarkable performance in several applications, were arranged diagonally
    among the perforated holes in order to make a new combination of micro-macro
    perforated plate. A 3D geometrical model of the plate was made in the Autodesk
    Inventor and the Finite Element (FE) simulation was employed to calculate the
    natural frequency and visualize the mode shape. Four models were made with
    various micro-holes diameter starting from 0,25, 0,5, 0,75 and 0,9 mm, respectively.
    The macro holes diameter, however, was kept constant to be 1,5 mm purposely to
    know the effect of micro holes in particular. The results from the models were then
    compared to a single perforated plate (PP) for clarification. It is found that the micro
    holes gives considerable effect to the perforated plate natural frequency. Similar to
    the author previous findings, the diameter of the micro holes is proportional to the
    natural frequency reduction.
    Matched MeSH terms: Finite Element Analysis
  14. Ishak MI, Kadir MR, Sulaiman E, Kasim NH
    Int J Oral Maxillofac Implants, 2013 May-Jun;28(3):e151-60.
    PMID: 23748334 DOI: 10.11607/jomi.2304
    To compare the extramaxillary approach with the widely used intrasinus approach via finite element method.
    Matched MeSH terms: Finite Element Analysis*
  15. Ishak MI, Abdul Kadir MR, Sulaiman E, Abu Kasim NH
    Int J Oral Maxillofac Surg, 2012 Sep;41(9):1077-89.
    PMID: 22575179 DOI: 10.1016/j.ijom.2012.04.010
    The aim of this study was to compare two different types of surgical approaches, intrasinus and extramaxillary, for the placement of zygomatic implants to treat atrophic maxillae. A computational finite element simulation was used to analyze the strength of implant anchorage for both approaches in various occlusal loading locations. Three-dimensional models of the craniofacial structures surrounding a region of interest, soft tissue and framework were developed using computed tomography image datasets. The implants were modelled using computer-aided design software. The bone was assumed to be linear isotropic with a stiffness of 13.4 GPa, and the implants were assumed to be made of titanium with a stiffness of 110 GPa. Masseter forces of 300 N were applied at the zygomatic arch, and occlusal loads of 150 N were applied vertically onto the framework surface at different locations. The intrasinus approach demonstrated more satisfactory results and could be a viable treatment option. The extramaxillary approach could also be recommended as a reasonable treatment option, provided some improvements are made to address the cantilever effects seen with that approach.
    Matched MeSH terms: Finite Element Analysis
  16. Isah BW, Mohamad H
    Sensors (Basel), 2021 Apr 22;21(9).
    PMID: 33922008 DOI: 10.3390/s21092926
    The paper explores the possibility of using high-resolution fiber Bragg grating (FBG) sensing technology for on-specimen strain measurement in the laboratory. The approach provides a means to assess the surface deformation of the specimen, both the axial and radial, through a chain of FBG sensor (C-FBG), in a basic setup of a uniaxial compression test. The method is cost-effective, straightforward and can be commercialized. Two C-FBG; one was applied directly to the sample (FBGBare), and the other was packaged (FBGPack) for ease of application. The approach measures the local strain with high-resolution and accuracy levels that match up to the existing local strain measuring sensors. The approach enables the evaluation of small-strain properties of the specimen intelligently. The finite element model analysis deployed has proven the adaptability of the technique for measuring material deformation. The adhesive thickness and packaging technique have been shown to influence the sensitivity of the FBG sensors. Owing to the relative ease and low-cost of instrumentation, the suggested method has a great potential to be routinely applied for elemental testing in the laboratory.
    Matched MeSH terms: Finite Element Analysis
  17. Hussin MS, Fernandez J, Ramezani M, Kumar P, Kelly PA
    Comput Methods Biomech Biomed Engin, 2020 Mar;23(4):143-154.
    PMID: 31928215 DOI: 10.1080/10255842.2019.1709118
    Osteoarthritis (OA) is a commonly occurring cartilage degenerative disease. The end stage treatment is Total Knee Arthroplasty (TKA), which can be costly in terms of initial surgery, but also in terms of revision knee arthroplasty, which is quite often required. A novel conceptual knee implant has been proposed to function as a reducer of stress across the joint surface, to extend the period of time before TKA becomes necessary. The objective of this paper is to develop a computational model which can be used to assess the wear arising at the implant articulating surfaces. Experimental wear coefficients were determined from physical testing, the results of which were verified using a semi-analytical model. Experimental results were incorporated into an anatomically correct computational model of the knee and implant. The wear-rate predicted for the implant was 27.74 mm3 per million cycles (MC) and the wear depth predicted was 1.085 mm/MC. Whereas the wear-rate is comparable to that seen in conventional knee implants, the wear depth is significantly higher than for conventional knee prostheses, and indicates that, in order to be viable, wear-rates should be reduced in some way, perhaps by using low-wear polymers.
    Matched MeSH terms: Finite Element Analysis
  18. Hassaballah AI, Hassan MA, Mardi AN, Hamdi M
    PLoS One, 2013;8(12):e82703.
    PMID: 24367544 DOI: 10.1371/journal.pone.0082703
    The determination of the myocardium's tissue properties is important in constructing functional finite element (FE) models of the human heart. To obtain accurate properties especially for functional modeling of a heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K = 1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the heart ejection fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle.
    Matched MeSH terms: Finite Element Analysis
  19. Harith H, Schmutz B, Malekani J, Schuetz MA, Yarlagadda PK
    Med Eng Phys, 2016 Mar;38(3):280-5.
    PMID: 26739124 DOI: 10.1016/j.medengphy.2015.11.012
    Anatomically precontoured plates are commonly used to treat periarticular fractures. A well-fitting plate can be used as a tool for anatomical reduction of the fractured bone. Recent studies highlighted that some plates fit poorly for many patients due to considerable shape variations between bones of the same anatomical site. While it is impossible to design one shape that fits all, it is also burdensome for the manufacturers and hospitals to produce, store and manage multiple plate shapes without the certainty of utilization by a patient population. In this study, we investigated the number of shapes required for maximum fit within a given dataset, and if they could be obtained by manually deforming the original plate. A distal medial tibial plate was automatically positioned on 45 individual tibiae, and the optimal deformation was determined iteratively using finite element analysis simulation. Within the studied dataset, we found that: (i) 89% fit could be achieved with four shapes, (ii) 100% fit was impossible through mechanical deformation, and (iii) the deformations required to obtain the four plate shapes were safe for the stainless steel plate for further clinical use. The proposed framework is easily transferable to other orthopaedic plates.
    Matched MeSH terms: Finite Element Analysis
  20. Hafizh M, Soliman MM, Qiblawey Y, Chowdhury MEH, Islam MT, Musharavati F, et al.
    Biosensors (Basel), 2023 Jan 02;13(1).
    PMID: 36671914 DOI: 10.3390/bios13010079
    In this paper, a surface acoustic wave (SAW) sensor for hip implant geometry was proposed for the application of total hip replacement. A two-port SAW device was numerically investigated for implementation with an operating frequency of 872 MHz that can be used in more common radio frequency interrogator units. A finite element analysis of the device was developed for a lithium niobate (LiNBO3) substrate with a Rayleigh velocity of 3488 m/s on COMSOL Multiphysics. The Multiphysics loading and frequency results highlighted a good uniformity with numerical results. Afterwards, a hip implant geometry was developed. The SAW sensor was mounted at two locations on the implant corresponding to two regions along the shaft of the femur bone. Three discrete conditions were studied for the feasibility of the implant with upper- and lower-body loading. The loading simulations highlighted that the stresses experienced do not exceed the yield strengths. The voltage output results indicated that the SAW sensor can be implanted in the hip implant for hip implant-loosening detection applications.
    Matched MeSH terms: Finite Element Analysis
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