scholarly journals Effects of Custom-Made Insole Materials on Frictional Stress and Contact Pressure in Diabetic Foot with Neuropathy: Results from a Finite Element Analysis

2021 ◽  
Vol 11 (8) ◽  
pp. 3412
Author(s):  
Muhammad Nouman ◽  
Tulaya Dissaneewate ◽  
Desmond Y. R. Chong ◽  
Surapong Chatpun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Diabetic Foot ◽  
Plantar Pressure ◽  
Frictional Stress ◽  
Pressure Reduction ◽  
Element Analysis ◽  
Custom Made ◽  
Peak Contact Pressure

Offloading plantar pressure in a diabetic foot with neuropathy is challenging in conventional clinical practice. Custom-made insole (CMI) materials play an important role in plantar pressure reduction, but the assessment is costly and time-consuming. Finite element analysis (FEA) can provide an efficient evaluation of different insoles on the plantar pressure distribution. This study investigated the effect of CMI materials and their combinations on plantar pressure reduction for the diabetic foot with neuropathy using FEA. The study was conducted by constructing a three-dimensional foot model along with CMI to study the peak contact pressure between the foot and CMI. The softer material (E = 5 MPa) resulted in a better reduction of peak contact pressure compared with the stiffer material (E = 11 MPa). The plantar pressure was well redistributed with softer material compared with the stiffer material and its combination. In addition, the single softer material resulted in reduced frictional stress under the first metatarsal head compared with the stiffer material and the combination of materials. The softer material and its combination have a beneficial effect on plantar pressure reduction and redistribution for a diabetic foot with neuropathy. This study provided an effective approach for CMI material selection using FEA.

scholarly journals Finite Element Approach Towards Selection of Appropriate Materials to Redistribute Peak Plantar Pressure in Diabetic Foot with Neuropathy

2021 ◽  
Vol 1 (2) ◽  
pp. 43-54
Author(s):  
Muhammad Nouman ◽  
Desmond Y.R. Chong ◽  
Surapong Chatpun
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Diabetic Foot ◽  
Plantar Pressure ◽  
Material Selection ◽  
Selection Process ◽  
Element Analysis ◽  
Layer Material ◽  
Peak Plantar Pressure ◽  
Peak Contact Pressure

Objective: The aim of this study was to assess the effect of customized insole (CMI) variations on plantar pressure in diabetic foot with neuropathy, using finite element analysis (FEA). Material and Methods: A three-dimensional foot model was constructed using FEA to study the peak contact pressure between the foot and the CMI. Nora® Lunalastike, Ethylene Vinyl Acetate (EVA), Amfit® and TPU were chosen for insole materials; and from these eight CMI models were created. The top surface of the tibia and fibula were fixed, and a displacement of 3 mm was exerted from the ground along with upwards Achilles tendon force.Results: The peak contact pressure contour showed that a softer material, CMI-A (E = 1.04 MPa), resulted in a better reduction of peak contact pressure compared to a stiffer material; CMI-D (E = 11 MPa). In addition, it was shown that the use of a single material to fabricate the CMI resulted in higher peak contact pressure; with the exception of CMI-A, in comparison to a dual-layer material of CMI-E and CMI-F. Using FEA, can effectively enhance the insole material selection process, without need of a trial and error practice in a clinical setting.Conclusion: The use of dual materials to fabricate CMIs, with the softer material as a top layer, is beneficial compared to a stiffer top layer material in the reduction of peak plantar pressure for diabetic foot with neuropathy.

scholarly journals Effect of cartilage thickness mismatch in osteochondral grafting from knee to talus on articular contact pressures: A finite element analysis

2021 ◽  
Vol 32 (2) ◽  
pp. 355-362
Author(s):  
Ömer Faruk Kılıçaslan ◽  
Ali Levent ◽  
Hüseyin Kürşat Çelik ◽  
Mehmet Ali Tokgöz ◽  
Özkan Köse ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Equivalent Stress ◽  
Cartilage Thickness ◽  
Frictional Stress ◽  
Element Analysis ◽  
Grafting From ◽  
Von Mises ◽  
Osteochondral Grafting

Objectives: The aim of this study was to investigate the effect of cartilage thickness mismatch on tibiotalar articular contact pressure in osteochondral grafting from femoral condyles to medial talar dome using a finite element analysis (FEA). Materials and methods: Flush-implanted osteochondral grafting was performed on the talar centromedial aspect of the dome using osteochondral plugs with two different cartilage thicknesses. One of the plugs had an equal cartilage thickness with the recipient talar cartilage and the second plug had a thicker cartilage representing a plug harvested from the knee. The ankle joint was loaded during a single-leg stance phase of gait. Tibiotalar contact pressure, frictional stress, equivalent stress (von Mises values), and deformation were analyzed. Results: In both osteochondral grafting simulations, tibiotalar contact pressure, frictional stress, equivalent stress (von Mises values) on both tibial and talar cartilage surfaces were restored to near-normal values. Conclusion: Cartilage thickness mismatch does not significantly change the tibiotalar contact biomechanics, when the graft is inserted flush with the talar cartilage surface.

Design and Performance Analysis of Vehicle Tyre Pattern Material Using Finite Element Analysis and ANSYS R16.2

2018 ◽  
Vol 777 ◽  
pp. 426-431
Author(s):  
S. Nallusamy ◽  
M. Rajaram Narayanan ◽  
R. Suganthini Rekha
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Equivalent Stress ◽  
Frictional Stress ◽  
Inflation Pressure ◽  
Element Analysis ◽  
Modeling Software ◽  
Element Approach ◽  
And Performance

As it stands now, rubber has been the main material used in the making of pneumatic vehicle tyres. Speed of the vehicle depends on many factors like steering geometry, inflation pressure, vehicle load, road temperature and environmental conditions. The main aim of this research is to develop a finite element approach and computationally evaluate the performance of a steady-state rolling tyre by changing the tyre tread patterns. The tyre normally composed of rubber and body-ply was investigated with regards to the effect of the inflation pressure. Tyre modeling using six different types of patterns was completed by using Creo parametric 3D modeling software and then the tyre was discretized into small elements through ANSYS R16.2. The rim area of the tyre was fixed and pressure was applied to the inside surface of the rim. Finite element analysis was completed by using ANSYS R16.2 and equivalent stress, contact stress and contact pressure were found out to identify the best tyre pattern. From the final results it was observed that, Pattern-I had good agreement of results as compared to other type of patterns which showed medium frictional stress and contact pressure.

scholarly journals Effect of coronal plane acetabular correction on joint contact pressure in Periacetabular osteotomy: a finite-element analysis

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Kenji Kitamura ◽  
Masanori Fujii ◽  
Miho Iwamoto ◽  
Satoshi Ikemura ◽  
Satoshi Hamai ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Periacetabular Osteotomy ◽  
Anterior Wall ◽  
Coronal Plane ◽  
Patient Specific ◽  
Element Analysis ◽  
Joint Contact ◽  
Joint Contact Pressure

Abstract Background The ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear. We aimed to determine the relationship between acetabular correction in the coronal plane and joint contact pressure (CP) and identify morphological factors associated with residual abnormal CP after correction. Methods Using CT images from 44 patients with hip dysplasia, we performed three patterns of virtual PAOs on patient-specific 3D hip models; the acetabulum was rotated laterally to the lateral center-edge angles (LCEA) of 30°, 35°, and 40°. Finite-element analysis was used to calculate the CP of the acetabular cartilage during a single-leg stance. Results Coronal correction to the LCEA of 30° decreased the median maximum CP 0.5-fold compared to preoperatively (p <  0.001). Additional correction to the LCEA of 40° further decreased CP in 15 hips (34%) but conversely increased CP in 29 hips (66%). The increase in CP was associated with greater preoperative extrusion index (p = 0.030) and roundness index (p = 0.038). Overall, virtual PAO failed to normalize CP in 11 hips (25%), and a small anterior wall index (p = 0.049) and a large roundness index (p = 0.003) were associated with residual abnormal CP. Conclusions The degree of acetabular correction in the coronal plane where CP is minimized varied among patients. Coronal plane correction alone failed to normalize CP in 25% of patients in this study. In patients with an anterior acetabular deficiency (anterior wall index < 0.21) and an aspherical femoral head (roundness index > 53.2%), coronal plane correction alone may not normalize CP. Further studies are needed to clarify the effectiveness of multiplanar correction, including in the sagittal and axial planes, in optimizing the hip joint’s contact mechanics.

scholarly journals An Analysis Tool for the Installation of Submarine Cables in an S-Lay Configuration Including “In and Out of Water” Cable Segments

2020 ◽  
Vol 8 (1) ◽  
pp. 48 ◽  
Author(s):  
Vasileios A. Mamatsopoulos ◽  
Constantine Michailides ◽  
Efstathios E. Theotokoglou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Criterion ◽  
Limiting Factors ◽  
Radius Of Curvature ◽  
Analysis Tool ◽  
Analysis Software ◽  
Element Analysis ◽  
Analysis And Design ◽  
Custom Made

Today, the offshore oil and gas and wind power industry is a heavily regulated segment, and current standards have established restrictions which yield a very limited weather window for submarine cable installations due to experience with cable failure in bad weather. There are two main limiting factors in current practice during cable installation of an S-lay configuration: the design criterion for the minimum allowable radius of curvature in the touch down point and the avoidance of axial compression in the touch down zone. Accurate assessment of the cable integrity during offshore installation has drawn great attention and is related to the existing available analysis and design tools. The main purpose of this paper is to develop and propose a quick and easy custom-made analysis tool, which is able to export similar results as sophisticated finite element analysis software. The developed tool utilizes analytical equations of a catenary-type submarine structure extended to account for varying cross-sections with different weights and/or stiffnesses, as is the real practice. A comparative study is presented in this paper to evaluate the significance for the modeling of the “out of water” cable segment required for accurate safety factor quantification during a laying operation. The efficiency and accuracy of the proposed tool are proven through a validation study comparing the results and the computational effort and time with commercial finite element analysis software. The analysis error in the case of not modeling the “out of water” cable part is significant, especially in shallow water areas, which proves the importance of using the proposed analysis tool.

Evaluation of the Elliptical Flange Configurations for 24-Inch and 30-Inch Heater/Cooler Units

2007 ◽  
Author(s):  
Chris Alexander ◽  
Wade Armer ◽  
Stuart Harbert
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Heat Exchanger ◽  
Contact Pressure ◽  
Parameter Study ◽  
Element Analysis ◽  
Iterative Design ◽  
Pressure Changes ◽  
Geometric Changes ◽  
Maximum Contact

KOCH Heat Transfer Company contracted Stress Engineering Services, Inc. to perform a design/parameter study of a return bonnet used in hairpin heat exchangers that employs an elliptical flange design. The return bonnet is an important component of the heat exchanger as it can be removed to permit inspection of the heat exchanger tubes. The return bonnet is bolted to the hairpin leg flange. To maintain sealing integrity a gasket is placed between the return bonnet flange and the hairpin leg flange. The sealing efficiency of two return bonnet sizes (24-inch and 30-inch) was investigated in this study using finite element analysis. The sealing efficiency is an indication of how the contact pressure changes circumferentially around the gasket and is calculated by dividing the local contact pressure by the maximum contact pressure calculated in the gasket for each respective design. The study assessed the effects of geometric changes to the mating flanges. Using an iterative design process using finite element analysis, the elliptical flanges were optimized to maximize sealing efficiency. Upon completion of the study, the manufacturer successfully employed the modifications as evidenced with multiple successful hydrotests.

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