scholarly journals Scaling of form and function in the xenarthran femur: a 100-fold increase in body mass is mitigated by repositioning of the third trochanter

2012 ◽  
Vol 279 (1742) ◽  
pp. 3449-3456 ◽  
Author(s):  
Nick Milne ◽  
Paul O'Higgins
Keyword(s):  
Finite Element ◽  
Fold Increase ◽  
Coronal Plane ◽  
Element Analysis ◽  
Geometric Morphometric ◽  
Form And Function ◽  
The Third ◽  
Before And After ◽  
Muscle Loading ◽  
And Function

How animals cope with increases in body size is a key issue in biology. Here, we consider scaling of xenarthrans, particularly how femoral form and function varies to accommodate the size range between the 3 kg armadillo and its giant relative the 300 kg glyptodont. It has already been noted that femoral morphology differs between these animals and suggested that this reflects a novel adaptation to size increase in glyptodont. We test this idea by applying a finite element analysis of coronal plane forces to femoral models of these animals, simulating the stance phase in the hind limb; where the femur is subject to bending owing to longitudinal compressive as well as abduction loads on the greater trochanter. We use these models to examine the hypothesis that muscles attaching on the third trochanter (T3) can reduce this bending in the loaded femur and that the T3 forces are more effective at reducing bending in glyptodont where the T3 is situated at the level of the knee. The analysis uses traditional finite element methods to produce strain maps and examine strains at 200 points on the femur. The coordinates of these points before and after loading are also used to carry out geometric morphometric (GM) analyses of the gross deformation of the model in different loading scenarios. The results show that longitudinal compressive and abductor muscle loading increases bending in the coronal plane, and that loads applied to the T3 reduce that bending. In the glyptodont model, the T3 loads are more effective and can more readily compensate for the bending owing to longitudinal and abductor loads. This study also demonstrates the usefulness of GM methods in interpreting the results of finite element analyses.

scholarly journals Craniofacial form and function in Metriorhynchidae (Crocodylomorpha: Thalattosuchia): modelling phenotypic evolution with maximum-likelihood methods

2011 ◽  
Vol 7 (6) ◽  
pp. 913-916 ◽  
Author(s):  
Mark T. Young ◽  
Mark A. Bell ◽  
Stephen L. Brusatte
Keyword(s):  
Maximum Likelihood ◽  
Phenotypic Evolution ◽  
Likelihood Methods ◽  
Element Analysis ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Form And Function ◽  
Maximum Likelihood Methods ◽  
Directional Change ◽  
And Function

Metriorhynchid crocodylomorphs were the only group of archosaurs to fully adapt to a pelagic lifestyle. During the Jurassic and Early Cretaceous, this group diversified into a variety of ecological and morphological types, from large super-predators with a broad short snout and serrated teeth to specialized piscivores/teuthophages with an elongate tubular snout and uncarinated teeth. Here, we use an integrated repertoire of geometric morphometric (form), biomechanical finite-element analysis (FEA; function) and phylogenetic data to examine the nature of craniofacial evolution in this clade. FEA stress values significantly correlate with morphometric values representing skull length and breadth, indicating that form and function are associated. Maximum-likelihood methods, which assess which of several models of evolution best explain the distribution of form and function data on a phylogenetic tree, show that the two major metriorhynchid subclades underwent different evolutionary modes. In geosaurines, both form and function are best explained as evolving under ‘random’ Brownian motion, whereas in metriorhynchines, the form metrics are best explained as evolving under stasis and the function metric as undergoing a directional change (towards most efficient low-stress piscivory). This suggests that the two subclades were under different selection pressures, and that metriorhynchines with similar skull shape were driven to become functionally divergent.

scholarly journals Evaluation of Stress Patterns in Bone Around Implants for Different Abutment Angulations Under Axial and Oblique Loading in Anterior Maxillary Region—A Finite Element Analysis

2020 ◽  
Vol 8 (02) ◽  
pp. 60-64
Author(s):  
Isha Badalia ◽  
Manjit Kumar ◽  
Ajay Bansal ◽  
Salil Mehra ◽  
Ritu Batra
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bone Resorption ◽  
Element Analysis ◽  
Natural Form ◽  
Form And Function ◽  
Anterior Teeth ◽  
Bone Width ◽  
Age Related ◽  
And Function

Abstract Introduction Replacing missing anterior teeth with a prosthesis that resembles natural form and function has always been challenging for a prosthodontist. Removable and fixed options both have been extensively studied and researched upon. In modern dentistry, implants have proved to be a more logical option for the same. The morphology of bone present in the premaxilla serves as guide to plan implant angulation during osteotomy. Factors such as age-related bone resorption, trauma or pathologic bone resorption due to periodontitis, etc. causes implants to be placed at angles that are difficult to restore with conventional straight abutments. Angled abutments can help build up favorable functional prosthesis in such cases, but they experience the drawback of transferring unfavorable forces to the implant or bone, thereby compromising the prognosis of the treatment. Clinically, the effect of these forces is difficult to evaluate, so a finite element analysis was done to estimate stress distribution at the bone implant interface. Materials and Methods In this study, premaxilla was modeled with 15 mm in bone height, 7 mm in bone length, and 12 mm in bone width with 1.5 mm thick cortical bone surrounded by a core of cancellous bone. The implant was modeled as a cylindrical, round-ended device with dimensions, 4.3 mm × 11.5 mm. Abutments with angulations 0°, 10°, 15° and 25° were used. To simulate clinical conditions, a 100 N load axially and 30 N load obliquely was applied. Result It was seen that, as the abutment angulation changes from 0° to 25°, both the compressive as well as tensile stresses increased; however, they were within the tolerance limit of the bone. Conclusion The study suggests angled abutments can be used with reasonable success, keeping in mind the basics of implant prosthodontics intact.

Weight-Reduction Optimization Design for Milling Planer Bed Based on Finite Element Analysis

2012 ◽  
Vol 490-495 ◽  
pp. 2785-2789
Author(s):  
Dong Sun ◽  
Xu Dong Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Weight Reduction ◽  
Optimization Design ◽  
Weak Link ◽  
Three Dimensional ◽  
Production Costs ◽  
Element Analysis ◽  
Before And After ◽  
Improvement Scheme

The milling planer bed is one of the most important foundational parts for the entire machine, sufficient stiffness is required. The posterior segment of a certain milling planer bed is regarded as the optimization object in this paper. Three-dimensional modeling method is used to calculate the exact weight of the bed and then finite element analysis is used to research the static and dynamic characteristics before and after weight-reduction. The weak link of the bed is found out and a improvement scheme is put forward ensuring lower production costs under the premise of sufficient rigidity.

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.

Integrating Genetic Algorithms and the Finite Element Analysis for Structural Inverse Problems

2011 ◽  
pp. 136-146
Author(s):  
D. C. Panni ◽  
A. D. Nurse
Keyword(s):  
Finite Element ◽  
Genetic Algorithms ◽  
Inverse Problems ◽  
Static Loading ◽  
Composite Structures ◽  
Specific Reference ◽  
Element Analysis ◽  
The Third ◽  
The Finite Element Analysis ◽  
Physical Response

A general method for integrating genetic algorithms within a commercially available finite element (FE) package to solve a range of structural inverse problems is presented. The described method exploits a user-programmable interface to control the genetic algorithm from within the FE package. This general approach is presented with specific reference to three illustrative system identification problems. In two of these the aim is to deduce the damaged state of composite structures from a known physical response to a given static loading. In the third the manufactured lay-up of a composite component is designed using the proposed methodology.

scholarly journals Finite element analysis of T-joint of mechanical connecting channels

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402097774
Author(s):  
Jiawei Wang ◽  
Fachao Li ◽  
Zibo Chen ◽  
Baishu Li ◽  
Jue Zhu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Rail Transit ◽  
Force Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
Before And After ◽  
Design Software

This paper studies the force and deformation of the connecting channel in Ningbo rail transit construction, which firstly used the mechanical shield method. Steel-concrete composite structural segments are used in the T-joint of connecting channel. The cutting part of the segments are replaced by the concrete and fiberglass instead of reinforced concrete. Basing on a variety of three-dimensional design software and ABAQUS finite element analysis software, a refined finite element analysis model of the special segments is established. By considering the influence of curved joint bolts, the force analysis of the special segments under the structural state before and after construction is performed. According to the analysis and comparison of the deformation of the segments with and without the bolts, it is concluded that the steel-concrete segments can withstand the pressure of the soil before and after the construction. Suggestions for the safety of the design and construction of the segments are put forward.

Airfoil Deformation Analysis During Stator Repair Process

2003 ◽  
Author(s):  
Shazia M. Alam ◽  
Mahdy Allam ◽  
Chittaranjan Sahay
Keyword(s):  
Finite Element ◽  
Coefficient Of Thermal Expansion ◽  
Repair Process ◽  
Deformation Analysis ◽  
Analysis Tool ◽  
Element Analysis ◽  
Jet Engine ◽  
Inconel Alloys ◽  
Before And After ◽  
History Of

The compressor stator assembly of a jet engine normally consists of stainless steel and Inconel alloys. Nickel based alloys can be also used as brazing material. Mechanical distortion of the stator assembly components may result during the brazing process. The coefficient of thermal expansion of the component materials, thermal history of manufacturing and operation also contribute to the stator deformation. The purpose of this work is to study the factors causing the distortion in vane stages. The study uses Finite Element Analysis tool ANSYS 5.7 for modeling the engine stator assembly. A finite element structural analysis of a single airfoil model is conducted at various repair points to assess the airfoil deformation and stress levels, before and after the brazing process. It is then used to identify materials and brazing parameters responsible for the observed distortion. The model analyzed shows general agreement between the numerical results and observations from the repair process. The probable causes of distortion are found and recommendations for fixing the distortion problem are also made.

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