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RISS 인기검색어
- 검색키워드
- 저자 : Nima Jamshidi (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Effects of Different Angles of the Traction Table on Lumbar Spine Ligaments: A Finite Element Study
Hekmat Farajpour,Nima Jamshidi 대한정형외과학회 2017 Clinics in Orthopedic Surgery Vol.9 No.4
Background: The traction bed is a noninvasive device for treating lower back pain caused by herniated intervertebral discs. In this study, we investigated the impact of the traction bed on the lower back as a means of increasing the disc height and creating a gap between facet joints. Methods: Computed tomography (CT) images were obtained from a female volunteer and a three-dimensional (3D) model was created using software package MIMICs 17.0. Afterwards, the 3D model was analyzed in an analytical software (Abaqus 6.14). The study was conducted under the following traction loads: 25%, 45%, 55%, and 85% of the whole body weight in different angles. Results: Results indicated that the loading angle in the L3–4 area had 36.8%, 57.4%, 55.32%, 49.8%, and 52.15% effect on the anterior longitudinal ligament, posterior longitudinal ligament, intertransverse ligament, interspinous ligament, and supraspinous ligament, respectively. The respective values for the L4–5 area were 32.3%, 10.6%, 53.4%, 56.58%, and 57.35%. Also, the body weight had 63.2%, 42.6%, 44.68%, 50.2%, and 47.85% effect on the anterior longitudinal ligament, posterior longitudinal ligament, intertransverse ligament, interspinous ligament, and supraspinous ligament, respectively. The respective values for the L4–5 area were 67.7%, 89.4%, 46.6%, 43.42% and 42.65%. The authenticity of results was checked by comparing with the experimental data. Conclusions: The results show that traction beds are highly effective for disc movement and lower back pain relief. Also, an optimal angle for traction can be obtained in a 3D model analysis using CT or magnetic resonance imaging images. The optimal angle would be different for different patients and thus should be determined based on the decreased height of the intervertebral disc, weight and height of patients.
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Evolutionary-base finite element model updating and damage detection using modal testing results
Mehdi Vahidi,Shahram Vahdani,Aicha Remil,Nima Jamshidi,Alireza Taghavee Kanee 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.3
This research focuses on finite element model updating and damage assessment of structures at element level based on global nondestructive test results. For this purpose, an optimization system is generated to minimize the structural dynamic parameters discrepancies between numerical and experimental models. Objective functions are selected based on the square of Euclidean norm error of vibration frequencies and modal assurance criterion of mode shapes. In order to update the finite element model and detect local damages within the structural members, modern optimization techniques is implemented according to the evolutionary algorithms to meet the global optimized solution. Using a simulated numerical example, application of genetic algorithm (GA), particle swarm (PSO) and artificial bee colony (ABC) algorithms are investigated in FE model updating and damage detection problems to consider their accuracy and convergence characteristics. Then, a hybrid multi stage optimization method is presented merging advantages of PSO and ABC methods in finding damage location and extent. The efficiency of the methods have been examined using two simulated numerical examples, a laboratory dynamic test and a high-rise building field ambient vibration test results. The implemented evolutionary updating methods show successful results in accuracy and speed considering the incomplete and noisy experimental measured data.
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Finite Element Modeling of the Compression Garments Structural Effect on the Pressure Applied to Leg
Ehsan Ghorbani,Hossein Hasani,Reza Jafari Nedoushan,Nima Jamshidi 한국섬유공학회 2020 Fibers and polymers Vol.21 No.3
Compression garments due to their numerous medical applications have been recently attracted to be mechanicallyanalyzed for their compression mechanism. Predicting the pressures applied to musculoskeletal tissues supported by thesegarments is a good solution for doing such analyzing which could be simply achieved by the help of finite element method. Inthis paper, the main aim was investigating the structural effect of knitted compression garments used for supporting the bodylower-limb musculoskeletal system. Compression garments of weft knitted rib structure containing elastane yarn wereprepared according to the leg’s dimensions of a healthy 27-year old person. Using Kikuhime measuring device, experimentalvalues of the applied pressure were measured in order to be compared with theoretical results. For developing a threedimensionalbiomechanical model for the leg system supported by compression garment, images form computed tomographyscanning methodology was used. Tensile properties of an elastane yarn as the basis for studying the compression garment’smechanical behavior were experimentally measured and then simulated in Abaqus software as a linear viscoelastic material. The results were then applied to multi-scale modeling technique in order to simulate mechanical behavior of the knitted fabricand the compression garment thereof. Combination of both experimental and theoretical results was applied to simulateinteractions between the leg and the compression garment. The results indicated that the pressure values simulated by finiteelement method were predicted with the maximum mean error of 19.64 % and total error mean of 12.29 % compared toexperimental results. Small difference between the measured and simulated values was observed for tibia and fibula becauseof their low soft-tissue volume. The proposed model enables the specialists to present compression garments based on thepatient’s needs and physician prescription which generate the optimal treatment.
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