Layer thickness and curvature effects on otoconial membrane deformation in the utricle of the red-ear slider turtle: Static and modal analysis

2008 ◽  
Vol 17 (4) ◽  
pp. 145-162
Author(s):  
J.L. Davis ◽  
J. Xue ◽  
E.H. Peterson ◽  
J.W. Grant
Keyword(s):  
Modal Analysis ◽  
Three Dimensional ◽  
Head Movements ◽  
Finite Element Models ◽  
Static Tests ◽  
Curvature Effects ◽  
Slider Turtle ◽  
Static Mechanical ◽  
Confocal Images ◽  
Geometric Variables

Finite element models of otoconial membrane (OM) were developed to investigate the effects of three geometric variables on static and modal response of the OM: (1) curvature of the macular surface, (2) spatial variation in thicknesses of three OM layers, and (3) shape of the macular perimeter. A geometrically accurate model of a turtle utricle was constructed from confocal images. Modifying values for each variable formed variants of this model: modeling the macula surface as flat, OM layer thicknesses as spatially invariant, and the macular perimeter as a rectangle. Static tests were performed on each modified OM model, and the results were compared to determine the effects of each geometric variable on static mechanical gain (deflection per unit acceleration). Results indicate that all three geometric variables affect the magnitude and directional properties of OM static mechanical gain. In addition, through modal analysis, we determined the natural frequencies and displacement modes of each model, which illustrate the effects of the three geometric variables on OM dynamics. This study indicates the importance of considering three-dimensional OM geometry when attempting to understand responses of the OM and, therefore, the modulation of hair cell signals to accelerations during head movements.

scholarly journals Modal analysis of a complex shell structure under operational loads

2021 ◽  
pp. 5-13
Author(s):  
Viktor Bazhenov ◽  
Olga Krivenko ◽  
Andrii Kozak
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Shell Structure ◽  
Cooling Tower ◽  
Three Dimensional ◽  
Integrated Approach ◽  
Wind Pressure ◽  
Step Method ◽  
Static Mechanical ◽  
The Moment

The results of calculation of a complex shell structure under the action of operational loads are presented. A three-section cooling tower, called a three-petal cooling tower, is regarded as a complex-shaped structure. Three variants of loads on the shell are considered: wind pressure, heating and load combination. The design model of a shell of a complex shape is based on the developed universal spatial finite element. The universal spatial finite element allows one to take into account the geometric features of structural elements for a thin shell (constant or varying thickness, knees, ribs, cover plates, holes, cavities, channels, inserts, facets) and multilayer structure of the material. According to the method, thin and medium thickness shells of various shapes and structures are considered. The shells are under the action of static mechanical and temperature loads. The finite element method is based on the unified positions of the three-dimensional geometrically nonlinear theory of thermoelasticity and the moment finite element scheme. The method for determining the natural vibrations of thin-walled shell structures is based on an integrated approach. Modal analysis is carried out taking into account the prestressed and deformed states of the shell at each step of thermomechanical loading. Thus, the problem of determining the natural frequencies and vibration modes of the shell is solved by the step method in two stages.

ACCURATE MODELING OF CURVED STEEL I-GIRDER BRIDGE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Yifan Zhu ◽  
Chaoran Xu ◽  
Chung C. Fu
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Vertical Shear ◽  
Finite Element Models ◽  
Refined Model ◽  
Shell Elements ◽  
Curvature Effects ◽  
Girder Bridges ◽  
Girder Bridge ◽  
Curved Steel

A curved and/or skewed steel I-girder bridge, in addition to the basic vertical shear and bending effects, will be subjected to torsional and warping effects. Thus, simplified hand calculation and line girder methods, might not be enough when bridges are to be analyzed. Refined methods, termed by AASHTO, have to be adopted. This paper has investigated the closeness and difference between curved bridge finite element models using 2-D gird and 3-D shell elements of I-girders, both are part of AASHTO refined method. Moreover, the results are calibrated by comparing analysis result with various two-dimensional and three-dimensional computations with varied curvature effects. It is concluded that when introducing torsional effects to finite element models, the modified torsional constant J with consideration of warping effect should be taken into the 2-D grid model as a refined model. When using 3-D shell elements as the refined model, stiffeners and connection plates play an important role of global model stiffness and should not be ignored, especially for sharp curved steel I-girder bridges.

Three-dimensional image analysis and visualization in confocal light microscopy

1993 ◽  
Vol 51 ◽  
pp. 158-159
Author(s):  
J. K. Samarabandu ◽  
R. Acharya ◽  
D. R. Pareddy ◽  
P. C. Cheng
Keyword(s):  
Depth Perception ◽  
Computer Graphic ◽  
Three Dimensional ◽  
Cellular Organization ◽  
Data Set ◽  
Computational Burden ◽  
Interactive Operation ◽  
Cell Organization ◽  
Confocal Images ◽  
3D Digitization

In the study of cell organization in a maize meristem, direct viewing of confocal optical sections in 3D (by means of 3D projection of the volumetric data set, Figure 1) becomes very difficult and confusing because of the large number of nucleus involved. Numerical description of the cellular organization (e.g. position, size and orientation of each structure) and computer graphic presentation are some of the solutions to effectively study the structure of such a complex system. An attempt at data-reduction by means of manually contouring cell nucleus in 3D was reported (Summers et al., 1990). Apart from being labour intensive, this 3D digitization technique suffers from the inaccuracies of manual 3D tracing related to the depth perception of the operator. However, it does demonstrate that reducing stack of confocal images to a 3D graphic representation helps to visualize and analyze complex tissues (Figure 2). This procedure also significantly reduce computational burden in an interactive operation.

scholarly journals Optimization of Polymer Extrusion Die Based on Response Surface Method

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1043 ◽  
Author(s):  
Amin Razeghiyadaki ◽  
Dichuan Zhang ◽  
Dongming Wei ◽  
Asma Perveen
Keyword(s):  
Three Dimensional ◽  
Theoretical Work ◽  
Optimization Method ◽  
Extrusion Die ◽  
Surface Method ◽  
Spline Fitting ◽  
Die Profile ◽  
Response Optimization ◽  
Geometric Variables ◽  
Volume Method

A coupled surface response optimization method with a three-dimensional finite volume method is adopted in this study to identify five independent geometric variables of the die interior that provides a design with the lowest velocity variance at the exit of the coat-hanger extrusion die. Two of these five geometric variables represent the manifold dimension while the other three variables represent the die profile. In this method, B-spline fitting with four points was used to represent the die profile. A comparison of the optimized die obtained in our study and the die with a geometry derived by a previous theoretical work shows a 20.07% improvement in the velocity distribution at the exit of the die.

Stiffness Constants for Composite Beams Including Large Initial Twist and Curvature Effects

1995 ◽  
Vol 48 (11S) ◽  
pp. S61-S67 ◽  
Author(s):  
Carlos E. S. Cesnik ◽  
Dewey H. Hodges
Keyword(s):  
Wave Length ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Cross Sectional ◽  
Curvature Effects ◽  
Three Dimensional Representation ◽  
Stiffness Model ◽  
Sectional Analysis ◽  
Three Dimensional Elasticity ◽  
Coupling Phenomena

An asymptotically exact methodology, based on geometrically nonlinear, three-dimensional elasticity, is presented for cross-sectional analysis of initially curved and twisted, nonhomogeneous, anisotropic beams. Through accounting for all possible deformation in the three-dimensional representation, the analysis correctly accounts for the complex elastic coupling phenomena in anisotropic beams associated with shear deformation. The analysis is subject only to the restrictions that the strain is small relative to unity and that the maximum dimension of the cross section is small relative to the wave length of the deformation and to the minimum radius of curvature and/or twist. The resulting cross-sectional elastic constants exhibit second-order dependence on the initial curvature and twist. As is well known, the associated geometrically-exact, one-dimensional equilibrium and kinematical equations also depend on initial twist and curvature. The corrections to the stiffness model derived herein are also necessary in general for proper representation of initially curved and twisted beams.

A Study on the Lower Flanges Fracture of Endplate Bolted Connection

2006 ◽  
Vol 326-328 ◽  
pp. 983-986
Author(s):  
Hong Wei Ma ◽  
Chong Du Cho ◽  
Qiang Pan ◽  
Hyeon Gyu Beom
Keyword(s):  
Crack Length ◽  
High Stress ◽  
Transverse Load ◽  
Stress Fields ◽  
Finite Element Models ◽  
J Integral ◽  
Bolted Connection ◽  
Static Tests ◽  
Opening Mode ◽  
Set Up

The quasi-static tests on the endplate bolted connections of the new structure system consisting of SCC beam and CCSHRC column are briefly introduced in this paper. Meanwhile, the 3-D solid finite element models of the connections with pre-existing cracks in the lower flange’s high stress fields are set up by ANSYS. The material nonlinearities of concrete, steel and bars, together with the contact between the endplate and column surface are all considered in the model. With the transverse load applied on top of columns, the fracture parameters are calculated by APDL. The results indicate that the opening mode crack will happen mainly. When the pre-existing crack length is 2.50mm and the inter-storey drift is less than 6mm, the stress intensity factor values agree well with the converting values derived from J-integral and the crack tip fields are in elastic state. The J values are highly influenced by the pre-existing crack length, while seldom influenced by the concrete compression strength. Moreover, the J-integral have the trend to sharply increase when the pre-existing crack length is larger than 0.61mm, and the pre-existing crack will grow during loading when its length is larger than 1.35mm.

Dynamics Analysis of Refrigeration Compressor Based on Finite Element and Experimental Modes

2012 ◽  
Vol 499 ◽  
pp. 238-242
Author(s):  
Li Zhang ◽  
Hong Wu ◽  
Yan Jue Gong ◽  
Shuo Zhang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Modal Analysis ◽  
Natural Frequency ◽  
High Precision ◽  
3D Model ◽  
Finite Element Models ◽  
Dynamics Analysis ◽  
Response Characteristics ◽  
Dynamic Response Characteristics

Based on the 3D model of refrigeration's compressor by Pro/E software, the analyses of theoretical and experimental mode are carried out in this paper. The results show that the finite element models of compressor have high precision dynamic response characteristics and the natural frequency of the compressor, based on experimental modal analysis, can be accurately obtained, which will contribute to further dynamic designs of mechanical structures.

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