Using Finite Element Analysis to Evaluate Countermeasures to Bone Demineralization During Long Duration Space Flight

1999 ◽  
Author(s):  
Benjamin M. Murphy ◽  
Linda C. Shackelford ◽  
Beth A. Todd ◽  
James F. Cuttino

Abstract During long duration space flight, astronauts must exercise to prevent bone demineralization. Exercises are used as countermeasures to the bone mineral loss. The effectiveness of the countermeasures is closely related to the mechanical stress developed during the exercises. A finite element model of the human femur was developed to determine the stress distribution during weight bearing. The model was developed using serial, transverse magnetic resonance images. The finite element analysis performed on the femur model showed an area of high stress in the femoral neck of approximately 1,200 psi. The highest stress seen in the model was approximately 2,000 psi. This information will then be used to evaluate the proposed exercises to be used as countermeasures.

Author(s):  
Ruchi D. Chande ◽  
John R. Owen ◽  
Robert S. Adelaar ◽  
Jennifer S. Wayne

The ankle joint, comprised of the distal ends of the tibia and fibula as well as talus, is key in permitting movement of the foot and restricting excessive motion during weight-bearing activities. Medial ankle injury occurs as a result of pronation-abduction or pronation-external rotation loading scenarios in which avulsion of the medial malleolus or rupture of the deltoid ligament can result if the force is sufficient [1]. If left untreated, the joint may experience more severe conditions like osteoarthritis [2]. To avoid such consequences, medial ankle injuries — specifically bony injuries — are treated with open reduction and internal fixation via the use of plates, screws, wires, or some combination thereof [1, 3–4]. In this investigation, the mechanical performance of two such devices was compared by creating a 3-dimensional model of an earlier cadaveric study [5], validating the model against the cadaveric data via finite element analysis (FEA), and comparing regions of high stress to regions of experimental failure.


2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.


Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1152
Author(s):  
Rafał Nowak ◽  
Anna Olejnik ◽  
Hanna Gerber ◽  
Roman Frątczak ◽  
Ewa Zawiślak

The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, the lack of updated reports about biomechanical effects in bone-borne appliances used in SARME is noticeable. Finite element analysis (FEA) was used for this study. Six facial skeleton models were created, five with various variants of osteotomy and one without osteotomy. Two different appliances for maxillary expansion were used for each model. The three-dimensional (3D) model of the facial skeleton was created on the basis of spiral computed tomography (CT) scans of a 32-year-old patient with maxillary constriction. The finite element model was built using ANSYS 15.0 software, in which the computations were carried out. Stress distributions and displacement values along the 3D axes were found for each osteotomy variant with the expansion of the tooth- and the bone-borne devices at a level of 0.5 mm. The investigation showed that in the case of a full osteotomy of the maxilla, as described by Bell and Epker in 1976, the method of fixing the appliance for maxillary expansion had no impact on the distribution of the reduced stresses according to Huber’s hypothesis in the facial skeleton. In the case of the bone-borne appliance, the load on the teeth, which may lead to periodontal and orthodontic complications, was eliminated. In the case of a full osteotomy of the maxilla, displacements in the buccolingual direction for all the variables of the bone-borne appliance were slightly bigger than for the tooth-borne appliance.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Daisuke Takahashi ◽  
Yoshihiro Noyama ◽  
Tsuyoshi Asano ◽  
Tomohiro Shimizu ◽  
Tohru Irie ◽  
...  

Abstract Background Internal fixation is recommended for treating Vancouver B1 periprosthetic femoral fractures. Although several fixation procedures have been developed with high fixation stability and union rates, long-term weight-bearing constructs are still lacking. Therefore, the aim of the present study was to evaluate the stability of a double-plate procedure using reversed contralateral locking compression-distal femoral plates for fixation of Vancouver B1 periprosthetic femoral fractures under full weight-bearing. Methods Single- and double-plate fixation procedures for locking compression-distal femoral plates were analysed under an axial load of 1,500 N by finite element analysis and biomechanical loading tests. A vertical loading test was performed to the prosthetic head, and the displacements and strains were calculated based on load-displacement and load-strain curves generated by the static compression tests. Results The finite element analysis revealed that double-plate fixation significantly reduced stress concentration at the lateral plate place on the fracture site. Under full weight-bearing, the maximum von Mises stress in the lateral plate was 268 MPa. On the other hand, the maximum stress in the single-plating method occurred at the defect level of the femur with a maximum stress value of 1,303 MPa. The principal strains of single- and double-plate fixation were 0.63 % and 0.058 %, respectively. Consistently, in the axial loading test, the strain values at a 1,500 N loading of the single- and double-plate fixation methods were 1,274.60 ± 11.53 and 317.33 ± 8.03 (× 10− 6), respectively. Conclusions The present study suggests that dual-plate fixation with reversed locking compression-distal femoral plates may be an excellent treatment procedure for patients with Vancouver B1 fractures, allowing for full weight-bearing in the early postoperative period.


2011 ◽  
Vol 346 ◽  
pp. 379-384
Author(s):  
Shu Bo Xu ◽  
Yang Xi ◽  
Cai Nian Jing ◽  
Ke Ke Sun

The use of finite element theory and modal analysis theory, the structure of the machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important. Selected for three-dimensional CAD modeling software-UG NX4.0 and finite element analysis software-ANSYS to set up the structure of the beam finite element model, and then post on the overall structure of the static and dynamic characteristic analysis, on the basis of optimized static and dynamic performance is more superior double wall structure of the beam. And by changing the wall thickness and the thickness of the inner wall, as well as the reinforcement plate thickness overall sensitivity analysis shows that changes in these three parameters on the dynamic characteristics of post impact. Application of topology optimization methods, determine the optimal structure of the beam ultimately.


Author(s):  
Luiz T. Souza ◽  
David W. Murray

The paper presents results for finite element analysis of full-sized girth-welded specimens of line pipe and compares these results with the behavior exhibited by test specimens subjected to constant axial force, internal pressure and monotonically increasing curvatures. Recommendations for the ‘best’ type of analytical finite element model are given. Comparisons between the behavior predicted analytically and the observed behavior of the experimental test specimens are made. The mechanism of wrinkling is explained and the evolution of the deformed configurations for different wrinkling modes is examined. It is concluded that the analytical tools now available are sufficiently reliable to predict the behavior of pipe in a manner that was not previously possible and that this should create a new era for the design and assessment of pipelines if the technology is properly exploited by industry.


2003 ◽  
Vol 15 (02) ◽  
pp. 82-85 ◽  
Author(s):  
SHYH-CHOUR HUANG ◽  
CHANG-FENG TSAI

This paper presents results from using a 3-dimensional finite element model to assess the stress distribution in the bone, in the implant and in the abutment as a function of the implant's diameter and length. Increasing implant diameter and length increases the stability of the implant system. By using a finite element analysis, we show that implant length does not decrease the stress distribution of either the implant or the bone. Alternatively, however implant diameter increases reduce the stresses. For the latter case, the contact area between implant and bone is increased thus the stress concentration effect is decreased. Also, with increased implant diameter the bone loss is decreased and as a consequence the success rate is improved.


2013 ◽  
Vol 774-776 ◽  
pp. 25-29
Author(s):  
Cong Fang Hu ◽  
Yuan Qiang Tan

Based on the tandem sealing structure at the end of the shaft,a finite element model of rubber O-rings has been established and the sealing performance of rubber O-ring has been analyzed. There is an un-uniform compression among these O-rings which lead to the sealing failure. Under different friction factors, several groups of the rubber O-rings have been analyzed, finding that the friction factor is the reason of un-uniform compression. The effect of different average compression rate has been investigated, which has been integrated in the sealing criteria for the tandem O-rings, providing a reference for the optimization of tandem sealing structure at the end of the shaft. According to the sealing criteria for a single O-ring, the sealing criteria for the tandem O-rings is built.


2010 ◽  
Vol 102-104 ◽  
pp. 17-21
Author(s):  
Bin Zhao

In order to study the static and dynamical characteristics of the crankshaft, ANSYS software was used to carry out the corresponding calculations. The entity model of the crankshaft was established by UG software firstly, and then was imported into ANSYS software for meshing, and then the finite element model of the crankshaft was constructed. The crankshaft satisfied the requirement of stiffness and strength through static analysis. The top six natural frequencies and corresponding shapes were acquired through modal analysis, and the every order critical rotating speed of the crankshaft was calculated. The fatigue life of the crank was calculated by fatigue module of ANSYS software finally. These results offered the theoretical guidance for designing, manufacturing and repairing the crankshaft.


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