scholarly journals Sublime recapitulation: Evolution of the appendicular skeleton of Australian Mekosuchinae crocodiles.

2017 ◽  
Author(s):  
Michael D Stein
Keyword(s):  
Finite Element ◽  
Morphological Variation ◽  
Middle Miocene ◽  
Pelvic Girdle ◽  
Appendicular Skeleton ◽  
Finite Element Analyses ◽  
Stress Variation ◽  
Geometric Morphometric ◽  
Collaborative Project ◽  
Hunting Strategies

Australian mekosuchines (Crocodylia; Crocodyloidea) with their wide diversity of cranial shape and inferred hunting strategies present a fascinating window into the diversification processes of crocodilians. This includes lingering questions as to the extent of any terrestrial habitus. A direct morphological signal for locomotion can be expected in the postcrania, particularly the girdles and the limbs of the appendicular skeleton. After a lengthy survey, enough materials of the pelvic girdle are available to chart morphological variation in the subfamily from Eocene through to middle Miocene. Over this period, the pelvis has undergone a vigorous morphological radiation. An enclosed, ventrally oriented acetabulum in the ilium developed in one lineage that apparently recapitulates the pillar-erect configuration of the pelvic girdle seen in many Mesozoic crocodilian lineages, suggesting consistent use of erect high-walk in these mekosuchines. Other pelves from Oligo–Miocene deposits display morphology closer to modern crocodilians despite clearly representing derived forms themselves, indicating a partition of locomotory strategy in the fauna during the Oligo–Miocene. While materials of hindlimb remain frustratingly lacking in light of this discovery, enough materials of forelimb humeri have been uncovered to chart the morphological variation in the subfamily from Eocene through to Pleistocene, corroborating what is seen in the pelvic girdle. As such, a collaborative project has been started that aims to quantitatively asses shape and stress variation in the mekosuchine forelimb using geometric morphometric and finite element analyses.

scholarly journals Sublime recapitulation: Evolution of the appendicular skeleton of Australian Mekosuchinae crocodiles.

2017 ◽  
Author(s):  
Michael D Stein
Keyword(s):  
Finite Element ◽  
Morphological Variation ◽  
Middle Miocene ◽  
Pelvic Girdle ◽  
Appendicular Skeleton ◽  
Finite Element Analyses ◽  
Stress Variation ◽  
Geometric Morphometric ◽  
Collaborative Project ◽  
Hunting Strategies

Australian mekosuchines (Crocodylia; Crocodyloidea) with their wide diversity of cranial shape and inferred hunting strategies present a fascinating window into the diversification processes of crocodilians. This includes lingering questions as to the extent of any terrestrial habitus. A direct morphological signal for locomotion can be expected in the postcrania, particularly the girdles and the limbs of the appendicular skeleton. After a lengthy survey, enough materials of the pelvic girdle are available to chart morphological variation in the subfamily from Eocene through to middle Miocene. Over this period, the pelvis has undergone a vigorous morphological radiation. An enclosed, ventrally oriented acetabulum in the ilium developed in one lineage that apparently recapitulates the pillar-erect configuration of the pelvic girdle seen in many Mesozoic crocodilian lineages, suggesting consistent use of erect high-walk in these mekosuchines. Other pelves from Oligo–Miocene deposits display morphology closer to modern crocodilians despite clearly representing derived forms themselves, indicating a partition of locomotory strategy in the fauna during the Oligo–Miocene. While materials of hindlimb remain frustratingly lacking in light of this discovery, enough materials of forelimb humeri have been uncovered to chart the morphological variation in the subfamily from Eocene through to Pleistocene, corroborating what is seen in the pelvic girdle. As such, a collaborative project has been started that aims to quantitatively asses shape and stress variation in the mekosuchine forelimb using geometric morphometric and finite element analyses.

scholarly journals Variation in the pelvic and pectoral girdles of Australian Oligo–Miocene mekosuchine crocodiles with implications for locomotion and habitus

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3501 ◽  
Author(s):  
Michael D. Stein ◽  
Adam Yates ◽  
Suzanne J. Hand ◽  
Michael Archer
Keyword(s):  
Morphological Variation ◽  
Middle Miocene ◽  
Iliac Crest ◽  
Morphological Changes ◽  
Parsimony Analysis ◽  
Crown Group ◽  
Hunting Strategies ◽  
Pelvic Limb ◽  
Relationship Of ◽  
Cranial Shape

Australian Oligo–Miocene mekosuchines (Crocodylia; Crocodyloidea) display wide diversity in cranial shape and inferred hunting strategies. Terrestrial habitus has been inferred for these distinctive predators. A direct morphological signal for locomotion can be expected in the postcrania, particularly the pelvic and pectoral girdles. Here we describe fossil materials of the girdles, which chart their morphological variation in the subfamily from Eocene through to Middle Miocene. Over this period, both girdles undergo significant morphological changes. Notably, an enclosed, ventrally orientated acetabulum in the ilium is developed in one lineage. This recapitulates the erect parasagittal configuration of the pelvic limb seen in many Mesozoic crocodylomorph lineages, suggesting consistent use of erect high-walking in these mekosuchines. Other pelves from the same Oligo–Miocene deposits display morphology closer to modern crocodilians, suggesting a partitioning of locomotory strategy among sympatric mekosuchines. Plesiomorphic and derived pelvic girdles are distinguishable by parsimony analysis, and the earliest examples of the mekosuchine pelvis more closely resemble gavialids and alligatorids while latter forms converge on crown group crocodylids in the morphology of the iliac crest. This suggests that a revaluation of the base relationship of Mekosuchinae within Eusuchia is necessary.

scholarly journals Investigation of Static, Modal and Harmonic vibration analyses of Single Row SKF6205 Deep Groove Ball Bearing for thermal applications

2021 ◽  
Vol 309 ◽  
pp. 01096
Author(s):  
M. Raju ◽  
S. Thiagarajan ◽  
D. Peter Pushpanathan ◽  
S. Selvarasu ◽  
S. Thirumavalavan ◽  
...  
Keyword(s):  
Finite Element ◽  
Ball Bearing ◽  
Research Work ◽  
Finite Element Analyses ◽  
Stress Variation ◽  
Single Row ◽  
Stochastic Conditions ◽  
Deep Groove ◽  
Deep Groove Ball Bearing ◽  
Mechanical Element

It is the necessary to predict the endurance capability of the mechanical element with its increased application and complexity. The present research work estimates the stress variation and displacement characteristics using finite element analyses of Single Row SKF6205 Deep Groove Ball Bearing under radial and axial loadings. The vibration analyses are evaluated in three aspects; static, modal, and harmonic analysis. The simulations show the variation of stress levels of the bearing in different loads. These results are used to predict the fatigue life, wear rate, and productivity of the ball bearing at various stochastic conditions.

Stress Variation in the Orthodontic Tipping Phenomenon Analysis through the finite element method

2018 ◽  
Vol 69 (8) ◽  
pp. 1992-1995
Author(s):  
Dan Dragos Sita ◽  
Ligia Brezeanu ◽  
Cristina Bica ◽  
Dana Manuc ◽  
Edwin Sever Bechir ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Alveolar Bone ◽  
Complex Structure ◽  
External Action ◽  
The Finite Element Method ◽  
Stress Variation ◽  
Orthodontic Bracket ◽  
Method Analysis ◽  
Element Method

The purpose of the study is to assess through a FEM (Finite Element Method analysis), the behavior of a complex structure (enamel-tooth-alveolar bone-periodontal ligament-pulp), subjected to an external load through an orthodontic bracket-with forces of various intensities and to determine its influence on the entire structure.It is necessary to analyze the way all elements of the structure take over the external action given by the action of an orthodontic appliance through the brackets and the influence on the inner component -the pulp-inside of which there are the nerve endings.

Design of flexure revolute joint based on compliance and stiffness ellipsoids

2021 ◽  
pp. 095441002110169
Author(s):  
Jing Zhang ◽  
Hong-wei Guo ◽  
Juan Wu ◽  
Zi-ming Kou ◽  
Anders Eriksson
Keyword(s):  
Finite Element ◽  
Single Point ◽  
Synthesis Method ◽  
Nonlinear Finite Element ◽  
Finite Element Analyses ◽  
Rotational Stiffness ◽  
Rotational Angle ◽  
Parameterized Model ◽  
Flexure Joints ◽  
Translational Stiffness

In view of the problems of low accuracy, small rotational angle, and large impact caused by flexure joints during the deployment process, an integrated flexure revolute (FR) joint for folding mechanisms was designed. The design was based on the method of compliance and stiffness ellipsoids, using a compliant dyad building block as its flexible unit. Using the single-point synthesis method, the parameterized model of the flexible unit was established to achieve a reasonable allocation of flexibility in different directions. Based on the single-parameter error analysis, two error models were established to evaluate the designed flexure joint. The rotational stiffness, the translational stiffness, and the maximum rotational angle of the joints were analyzed by nonlinear finite element analyses. The rotational angle of one joint can reach 25.5° in one direction. The rotational angle of the series FR joint can achieve 50° in one direction. Experiments on single and series flexure joints were carried out to verify the correctness of the design and analysis of the flexure joint.

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