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 ◽  
...  

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.

2018 ◽  
Vol 777 ◽  
pp. 426-431
Author(s):  
S. Nallusamy ◽  
M. Rajaram Narayanan ◽  
R. Suganthini Rekha

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.


Author(s):  
Young-Doo Kwon ◽  
Jin-Sik Han

Structural elements like bars, trusses, beams, frames, plates, and shells have long been used in structures and machines because of their large stiffness-to-weight ratios. The Euler–Bernoulli theory for beam elements is currently used in a wide range of engineering fields. Frames may essentially be considered to be a type of general beam with axial loads. In the analysis of a right-angle frame, the stiffness of a corner has been assumed to be infinite, which is allowable only when the frame is sufficiently slender. However, a comparison of the results of a finite element analysis showed that the assumption of rigid corner stiffness is unacceptable for most cases because of the considerable errors that result. To resolve this problem, we assumed that the stiffness of a corner in a right-angle frame was finite, which is mostly the case, and solved the problem of a right-angle frame with round corners under internal pressure. Using the derived formula based on the assumption of finite corner stiffness and the formula for the round corner stiffness, we analyzed the entire right-angle frame structure and compared the results to finite element analysis results. As a final attempt, the quasi-optimal dimension of the corner was found to exhibit the lowest von Mises equivalent stress. This proposed approach could be applied to many problems involving frames with various boundary conditions to improve the accuracy.


2011 ◽  
Vol 199-200 ◽  
pp. 1595-1599
Author(s):  
Dian Xin Li ◽  
Hong Lin Zhao ◽  
Shi Min Zhang ◽  
Chang Run Wu ◽  
Xian Long Liu ◽  
...  

Based on finite element analysis software ANSYS, the deformation and force condition of the rubber sealing o-ring pre and post with back-up ring under different oil pressure conditions was analyzed. The von mises stress distribution of the o-ring and the change of contact pressure between o-ring and sealing interface pre and post with back-up ring under different oil pressure conditions were discussed. The results show that, the maximum von mises stress of the o-ring is smaller and the maximum von mises stress of the sealing system concentrates on the left top and the right bottom of the back-up ring after using it; the o-ring will not be extruded into the gap of the groove because of the existence of back-up ring which prevents gap-bite and prolongs service life of the o-ring; the contact pressure between o-ring and sealing interface increased, thus the sealing reliability of the system increased.


2021 ◽  
Vol 1 (109) ◽  
pp. 29-34
Author(s):  
D.I. Tsamroh

Purpose: To analyze and estimate the strength of duralium rivets which had been treated by using multistage artificial aging compared with duralium that had not been treated. This processwas necessary to be conducted in riveting process effectively. Duralium has been widely used in aerospace industry, one of duralium usage in aerospace industry is aircraft fittings such as rivet. Riveting is one of method that used for joining airframe structural components. During riveting process, the load transfer causing stress that led to the fatigue. Riveting process also causes deformation on the rivet and sheet metal. Deformation that occurs on the rivet will affect the performance of rivet structure. Thus, duralium rivet was analyzed its total deformation, shear stress, and its equivalent stress Von Misses. Design/methodology/approach: that used in this study was finite element analysis. Geometry of rivet that used in this study was drawn by using Autodesk Inventor Professional 2018. While total deformation, shear stress and equivalent stress Von Mises on duralium rivets were found out by using ANSYS Workbench 18.1. Findings: Comparison result was obtained between duralium rivet with and without treatment of multistage artificial aging. The result shown that total deformation, shear stress and equivalent stress Von Mises which obtained by duralium rivet with multistage artificial aging had the lower value than duralium rivet without multistage artificial aging. Duralium rivet with multistage artificial aging could be used as aircraft fitting which had the higher strength. Research limitations/implications: Direct experiment on duralium rivet had not been done yet, this study only did simulation based on data that obtained form previous research that had been conducted by the researcher. Practical implications: Duralium rivet with multistage artificial aging had lower value on total deformation, shear stress, and equivalent stress Von Misses, thus duralium rivet with multistage aritificial aging had a higher strength.


2014 ◽  
Vol 577 ◽  
pp. 218-221 ◽  
Author(s):  
Yan Jie Guo ◽  
Wei Wang ◽  
Qing Dong Cui ◽  
Hui Dou

The lateral longitudinal beam is one of the most important mechanical parts in secondary protection equipment of electrical power system. Basing on the simulation analysis platform of ANSYS Workbench, the standardization of the modular hole of the lateral longitudinal beam is studied in this research. The static and dynamic finite element analysis of the lateral longitudinal beam are used to obtain Von-Mises equivalent stress, deformation data, the natural frequency and vibration mode of five orders. The contrastive analysis of the results of finite element analysis provides a kind of theoretical instruction for the dimension selection of the modular hole.


Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis

Plastic collapse analysis and remaining burst strength determination are critical to a corroded pipeline in its fitness-for-service analysis and integrity assessment. For very long corrosion defects, the present authors proposed a theoretical solution for predicting the burst pressure of corroded pipe in terms of a newly developed average shear stress yield theory, and validated it using full-scale burst data for long real corrosion defects. This paper then presents a finite element analysis (FEA) procedure to determine the remaining burst pressure for a very long blunt defect. A burst failure criterion that is referred to as von Mises equivalent stress criterion is proposed first in reference to the von Mises theory. Detailed elastic-plastic FEA calculations are performed using ABAQUS for a series of corroded pipes with infinitely long defects in different widths. From the FEA results and using the proposed failure criterion, the numerical results of burst pressure are determined for the long defects. The results show that using the proposed failure criterion, the FEA simulation can accurately determine the burst pressure for corroded pipes with long defects that is consistent with the theoretical solution. The conventional assessment methods including ASME B31G, RSTRENG, PCORRC and LPC are also evaluated and discussed in comparison with the proposed theoretical solution of burst pressure for long corrosion defects.


2021 ◽  
Vol 11 (8) ◽  
pp. 3412
Author(s):  
Muhammad Nouman ◽  
Tulaya Dissaneewate ◽  
Desmond Y. R. Chong ◽  
Surapong Chatpun

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.


Author(s):  
Bummo Chung ◽  
Itzhak Green ◽  
Richard S. Cowan

This work presents a finite element analysis (FEA) of the initial armature-to-rail contact of a lab-scale electromagnetic accelerator (12.5 mm rail height) and a modal analysis of the armature. Structural results of the von Mises stress, the contact pressure, and the contact area are presented with the vibrational characteristics (frequencies and mode shapes) of the un-stressed and the pre-stressed armature.


2021 ◽  
Vol 11 (6) ◽  
pp. 2547 ◽  
Author(s):  
Carlo Prati ◽  
João Paulo Mendes Tribst ◽  
Amanda Maria de Oliveira Dal Piva ◽  
Alexandre Luiz Souto Borges ◽  
Maurizio Ventre ◽  
...  

The aim of the present investigation was to calculate the stress distribution generated in the root dentine canal during mechanical rotation of five different NiTi endodontic instruments by means of a finite element analysis (FEA). Two conventional alloy NiTi instruments F360 25/04 and F6 Skytaper 25/06, in comparison to three heat treated alloys NiTI Hyflex CM 25/04, Protaper Next 25/06 and One Curve 25/06 were considered and analyzed. The instruments’ flexibility (reaction force) and geometrical features (cross section, conicity) were previously investigated. For each instrument, dentine root canals with two different elastic moduli(18 and 42 GPa) were simulated with defined apical ratios. Ten different CAD instrument models were created and their mechanical behaviors were analyzed by a 3D-FEA. Static structural analyses were performed with a non-failure condition, since a linear elastic behavior was assumed for all components. All the instruments generated a stress area concentration in correspondence to the root canal curvature at approx. 7 mm from the apex. The maximum values were found when instruments were analyzed in the highest elastic modulus dentine canal. Strain and von Mises stress patterns showed a higher concentration in the first part of curved radius of all the instruments. Conventional Ni-Ti endodontic instruments demonstrated higher stress magnitudes, regardless of the conicity of 4% and 6%, and they showed the highest von Mises stress values in sound, as well as in mineralized dentine canals. Heat-treated endodontic instruments with higher flexibility values showed a reduced stress concentration map. Hyflex CM 25/04 displayed the lowest von Mises stress values of, respectively, 35.73 and 44.30 GPa for sound and mineralized dentine. The mechanical behavior of all rotary endodontic instruments was influenced by the different elastic moduli and by the dentine canal rigidity.


Author(s):  
Osezua Obehi Ibhadode ◽  
Ishaya Musa Dagwa ◽  
Akii Okonigbon Akhaehomen Ibhadode

Calibration curves of a multi-component dynamometer is of essence in machining operations in a lathe machine as they serve to provide values of force and stress components for cutting tool development and optimization. In this study, finite element analysis has been used to obtain the deflection and stress response of a two component cutting tool lathe dynamometer, for turning operation, when the cutting tool is subjected to cutting and thrust forces from 98.1N to 686.7N (10 to 70kg-wts), at intervals of 98.1N(10kg-wt). By obtaining the governing equation, modeling the dynamometer assembly, defining boundary conditions, generating the assembly mesh, and simulating in Inventor Professional; horizontal and vertical components of deflection by the dynamometer were read off for three different loading scenarios. For these three loading scenarios, calibration plots by experiment compared with plots obtained from simulation by finite element analysis gave accuracies of 79%, 95%, 84% and 36%, 57%, 63% for vertical and horizontal deflections respectively. Also, plots of horizontal and vertical components of Von Mises stress against applied forces were obtained.


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