scholarly journals Finite Element Biomechanics of Optic Nerve Sheath Traction in Adduction

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Andrew Shin ◽  
Lawrence Yoo ◽  
Joseph Park ◽  
Joseph L. Demer
Keyword(s):  
Finite Element ◽  
Optic Nerve ◽  
Young’S Modulus ◽  
Optic Neuropathy ◽  
Maximum Stress ◽  
Young's Modulus ◽  
Tensile Elongation ◽  
Glaucomatous Optic Neuropathy ◽  
Stress And Strain ◽  
Element Analysis

Historical emphasis on increased intraocular pressure (IOP) in the pathogenesis of glaucoma has been challenged by the recognition that many patients lack abnormally elevated IOP. We employed finite element analysis (FEA) to infer contribution to optic neuropathy from tractional deformation of the optic nerve head (ONH) and lamina cribrosa (LC) by extraocular muscle (EOM) counterforce exerted when optic nerve (ON) redundancy becomes exhausted in adduction. We characterized assumed isotropic Young's modulus of fresh adult bovine ON, ON sheath, and peripapillary and peripheral sclera by tensile elongation in arbitrary orientations of five specimens of each tissue to failure under physiological temperature and humidity. Physical dimensions of the FEA were scaled to human histological and magnetic resonance imaging (MRI) data and used to predict stress and strain during adduction 6 deg beyond ON straightening at multiple levels of IOP. Young's modulus of ON sheath of 44.6 ± 5.6 MPa (standard error of mean) greatly exceeded that of ON at 5.2 ± 0.4 MPa, peripapillary sclera at 5.5 ± 0.8 MPa, and peripheral sclera at 14.0 ± 2.3 MPa. FEA indicated that adduction induced maximum stress and strain in the temporal ONH. In the temporal LC, the maximum stress was 180 kPa, and the maximum strain was ninefold larger than produced by IOP elevation to 45 mm Hg. The simulation suggests that ON sheath traction by adduction concentrates far greater mechanical stress and strain in the ONH region than does elevated IOP, supporting the novel concept that glaucomatous optic neuropathy may result at least partly from external traction on the ON, rather than exclusively on pressure on the ON exerted from within the eye.

scholarly journals Finite Element Analysis of Needle Insertion Angle in Insulin Therapy

2019 ◽  
Vol 16 (4) ◽  
pp. 7512-7523
Author(s):  
Syakirah Mohamed Amin ◽  
Muhammad Hanif Ramlee ◽  
Hadafi Fitri Mohd Latip ◽  
Gan Hong Seng ◽  
Mohammed Rafiq Abdul Kadir
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Insulin Therapy ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Needle Insertion ◽  
Stress And Strain ◽  
Medical Doctors ◽  
Element Analysis ◽  
Biomechanical Evaluation

Millions in the world suffering diabetes mellitus depends on insulin therapy to control their blood glucose level daily. However, the painful daily injections they need to take could lead to other complications if it is not done correctly. To date, it is suggested by many researchers and medical doctors that the needles should be inserted at any angles of 90º or 45º. Nevertheless, this recommendation has not been supported by clinical or biomechanical evaluation. Hence, this study evaluates the needle insertion for insulin therapy to find the favourable angles in order to reduce injury and pain onto the skin. Finite element analysis was done by  simulating the injection of three-dimensional (3D) needle model into a 3D skin model. The insertions were simulated at two different angles, which are 45ºand 90º with two different lengths of needles; 4 mm and 6 mm. This study concluded the favourable angle for 4 mm needle to be 90º while 6 mm needle was best to be inserted at 45º as these angles exerted the least maximum stress and strain onto the skin.

scholarly journals Finite Element Analysis of the Nanomechanics of Hard Coatings on a Soft Polymer Substrate by a Spherical Indenter

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Chunlai Tian ◽  
Pengfei Duan
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Viscoelastic Model ◽  
Coating System ◽  
Element Analysis ◽  
Soft Polymer ◽  
Indentation Response

Composite has been widely used in various fields due to its advanced performance. To reveal the relation between the mechanical properties of the composite and that of each individual component, finite element analysis (FEA) has usually been adopted. In this study, in order to predict the mechanical properties of hard coating on a soft polymer, the response of this coating system during nanoindentation was modelled. Various models, such as a viscoelastic model and fitting model, were adopted to analyse the indentation response of this coating system. By varying the substrate properties (i.e., Young’s modulus, viscoelasticity, and Poisson’s ratio), Young’s modulus, energy loss, and the viscoelastic model of the coating system were analysed, and how the mechanical properties of the substrate will affect the indentation response of the coating system was discussed.

Sensitivity of lightweight deflectometer deflections to layer stiffness via finite element analysis

2015 ◽  
Vol 52 (7) ◽  
pp. 961-970 ◽  
Author(s):  
Christopher T. Senseney ◽  
Jacob Grasmick ◽  
Michael A. Mooney
Keyword(s):  
Finite Element ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Experimental Studies ◽  
Fe Model ◽  
Element Analysis ◽  
Soil System ◽  
Dynamic Finite Element ◽  
Back Calculation ◽  
Measurement Depth

A dynamic finite element (FE) model of lightweight deflectometer (LWD) loading on a two-layer soil system, validated with an analytical solution and experimental data, is presented. Peak dynamic FE vertical deflections can be substantially different (almost always smaller) than FE static deflections. The numerically simulated measurement depth of the LWD center sensor is found to be 2–2.5 times the plate diameter, deeper than other experimental studies. Using the FE model, we conduct a sensitivity analysis of peak vertical deflections to the top layer Young’s modulus and underlying Young’s modulus of two-layer systems. Peak deflections from the center sensor are found to be more sensitive to the top layer Young’s modulus while peak deflections at radial offsets are found to be more sensitive to the underlying layer Young’s modulus. Sensitivities of layer moduli to FE deflections offer guidance in selecting weighting factors for the inverse solver in an LWD back-calculation procedure.

scholarly journals Finite Element Analysis of Stress on Cross-Wavy Primary Surface Recuperator Based on Thermal-Structural Coupling Model

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohong Gui ◽  
Xiange Song ◽  
Haiwen Gong ◽  
Dianbao Yao ◽  
Ruogu Chen ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Pressure Ratio ◽  
Stress And Strain ◽  
Inlet Temperature ◽  
Element Analysis ◽  
Structural Coupling ◽  
Research Results ◽  
Air Passage

In order to study the stress, strain and deformation of the recuperator, the thermal-structural coupling finite element analysis model of cross-wavy primary surface recuperator of gas microturbine was established. The stress of cross-wavy primary surface recuperator after operation under design conditions was analyzed by finite element method. The reliability of the material selected for the recuperator was verified, and the effects of pressure ratio and gas inlet temperature on stress and displacement of the recuperator were analyzed. The research results show that the maximum stress and strain on the gas outlet side of the recuperator are higher than the maximum stress and strain on the gas inlet side when only pressure is considered, and the result is the opposite when pressure and thermal stress are considered. The air passage of the recuperator deforms to the side of the gas passage, the air passage becomes larger, and the gas passage shrinks. With the increase of pressure ratio between air side and gas side, the maximum stress of recuperator passage also increases. When the pressure ratio increases to 8.4, the strength limit of the heat exchange fin material is reached. When the gas and air outlet temperatures remain unchanged and the thermal ratio decreases, as the gas inlet temperature increases, the maximum stress increases. For every 50 K increase in the gas inlet temperature, the maximum stress of the recuperator increases by about 2.3 MPa. The research results can be used to guide the designing and optimization of recuperator.

scholarly journals Finite Element Analysis on Pelvis With Leg Length Inequality

2018 ◽  
Vol 7 (4.30) ◽  
Author(s):  
N. F. Othman ◽  
H. Y. Tan ◽  
K. S. Basaruddin ◽  
M. H. Mat Som ◽  
W. M. R. Rusli ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Pelvic Tilt ◽  
Pelvic Bone ◽  
Stress And Strain ◽  
Leg Length ◽  
Element Analysis ◽  
Leg Length Inequality ◽  
Human Bones

Leg length inequality, also known as leg length discrepancy (LLD) is a condition which the left and right legs of an individual are noticeably different in length. When the level of LLD is high, such as those of 20 mm and above, it would disturb the wellbeing of an individual in terms of gait, and also causes them to experience higher stress in their pelvis compared to individual without LLD. In order to study load due to LLD had affects human bones such as the pelvic bone, finite element analysis (FEA) approach is usually used as it allows limitless attempt to investigate the stress-strain response on human bones and is far more practical than experimenting on real bones, therefore FEA was done with by using ANSYS 15.0. From the data obtained via FEA, the risk of fracture can be calculated, which gives us an insight on how would LLD affects the risk of bone fracture. In this study the effect of pelvic tilt caused by LLD has been studied, along with how loads at various LLD level affects the pelvic bone. The verdict from the study is the pelvic tilt caused by LLD amplifies the maximum stress and strain on the pelvic bone. The analysis using hip load due to LLD shows a downtrend for the maximum stress caused by the longer limb as the level of LLD increases, while the maximum stress caused by the shorter limb shows an uptrend with the increment of LLD. The maximum stress and strain observed are usually distributed around the sacroiliac joint. It is also observed that the higher the level of LLD is, the higher the maximum stress on pelvic bone will become, hence the higher the fracture risk.

scholarly journals Finite Element Analysis of the Mechanism of Traumatic Aortic Rupture (TAR)

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
JiFeng Nan ◽  
Mohammadreza Rezaei ◽  
Rashid Mazhar ◽  
Fadi Jaber ◽  
Farayi Musharavati ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Fe Simulation ◽  
Aortic Rupture ◽  
Stress And Strain ◽  
Element Analysis ◽  
Car Crash ◽  
The Finite Element Analysis ◽  
Aorta Injury

As many as 80% of patients with TAR die on the spot while out of those reaching a hospital, 30% would die within 24 hours. Thus, it is essential to better understand and prevent this injury. The exact mechanics of TAR are unknown. Although most researchers approve it as a common-sense deceleration injury, the exact detailed mechanism of TRA still remains unidentified. In this work, a deceleration mechanism of TAR was carried out using finite element analysis (FEA). The FE analysis aimed to predict internal kinematics of the aorta and assist to comprehend the mechanism of aorta injury. The model contains the heart, lungs, thoracic aorta vessel, and rib cage. High-resolution computerized tomography (HR CT scan) was used to provide pictures that were reconstructed by MIMICS software. ANSYS FE simulation was carried out to investigate the behavior of the aorta in the thoracic interior after deceleration occurred during a car crash. The finite element analysis indicated that maximum stress and strain applied to the aorta were from 5.4819e5 to 2.614e6 Pa and 0.21048 to 0.62676, respectively, in the Y-direction when the initial velocity increased from 10 to 25 m/s. Furthermore, in the X-direction when the velocity changed from 15 to 25 m/s, the stress and strain values increased from 5.17771e5 to 2.3128e6 and from 0.22445 to 0.618, respectively.

Contribution of Three-Dimensional Trabecular Bone Microstructure of the Proximal Femur to its Mechanical Properties as Assessed by Micro-Finite Element Analysis

2006 ◽  
Vol 321-323 ◽  
pp. 278-281
Author(s):  
Wen Quan Cui ◽  
Ye Yeon Won ◽  
Myong Hyun Baek ◽  
Kwang Kyun Kim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Trabecular Bone ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Bone Microarchitecture ◽  
Element Model ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Element Analysis

The purpose of this study was to investigate the contribution of the microstructural properties of trabecular bone in predicting its elastic modulus in the intertrochanteric region. A total of 15 trabecular bone core specimens were obtained from the proximal femurs of patients undergoing total hip arthroplasty. The micro-computed tomography (micro-CT) was used to scan each specimen to obtain micro-morphology. Microstructural parameters were directly calculated using software. Micro-CT images were converted to micro-finite element model using meshing technique, and then micro-finite element analysis (FEA) was performed to assess the mechanical property (Young’s modulus) of trabecular bone. The results showed that the ability to explain this variance of Young’s modulus is improved by combining the structural indices with each other. It suggested that assessment of bone microarchitecture should be added as regards detection of osteoporosis and evaluation of the efficacy of drug treatments for osteoporosis.

Determination of the Young’s modulus of porous ß-type Ti–40Nb by finite element analysis

2014 ◽  
Vol 64 ◽  
pp. 1-8 ◽  
Author(s):  
K. Zhuravleva ◽  
R. Müller ◽  
L. Schultz ◽  
J. Eckert ◽  
A. Gebert ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Element Analysis
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