Mechanical Performance of Tubular Microtruss Materials Reinforced With Nanocrystalline Sleeves

2011 ◽  
Vol 1304 ◽  
Author(s):  
Eral Bele ◽  
Mishaal Azhar ◽  
Glenn D. Hibbard
Keyword(s):  
Mechanical Performance ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Structural Performance ◽  
Element Analysis ◽  
Cross Sectional ◽  
Polymeric Scaffolds ◽  
Characteristic Features ◽  
Inherent Strength ◽  
Material Grain Size

ABSTRACTMicrotruss cellular materials are assemblies of struts with characteristic features in the μm to mm scale, arranged in a periodic, three-dimensional architecture. Compared to conventional cellular architectures (e.g. stochastic foams and honeycombs), they can possess improved structural efficiency, because externally applied loads are resolved axially along the constituent struts. We have recently fabricated composite microtruss materials by electrodepositing reinforcing nanocrystalline sleeves on tubular polymeric scaffolds. These materials can offer enhanced structural performance by exploiting advantageous properties along three length scales: the inherent strength of the electrodeposited material (grain size reduction to the nm scale), its location away from the bending axis of the struts (cross-sectional efficiency in the μm scale), and the spatial arrangement of the struts (architectural efficiency in the mm scale). This study uses finite element analysis and experimental methods to characterize the mechanical properties of these composite materials.

scholarly journals Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Transition Zone ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Body Plan ◽  
The Body ◽  
Vascular Bundles ◽  
Cross Sectional ◽  
Thin Sections ◽  
Transition Zones ◽  
The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

Contribution in Optimization of Honeycomb Abradable Seals Structure

2021 ◽  
Author(s):  
P. Pathak ◽  
D. Dzhurinskiy ◽  
A. Elkin ◽  
P. Shornikov ◽  
S. Dautov ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Energy Demand ◽  
Mechanical Performance ◽  
Minimum Weight ◽  
Innovative Technology ◽  
Element Analysis ◽  
Cross Sectional ◽  
Spray System ◽  
Seal Design ◽  
Temperature Capability

Abstract The abradable coatings had significantly enhanced turbomachinery performance by acting as a sacrificial seal between rotating blades and stationary casing. Further improvement in seal design to meet the higher energy demand and increase the service time has been the key challenges to solve in the gas turbine industry. Honeycomb seals have become the industry standard clearance seal technique due to their unique design and high structural strength with minimum weight. The present study proposes a concept to form a thermal shock resistance structure to achieve higher temperature capability and improve the reliability of abradable seal structures. A cavity layer of honeycomb seal structure made of SS 321 alloy was coated with advanced high-temperature ZrO2+7.5%Y2O3+4% polyester seal material using TriplexPro-210 plasma spray system. The integrity of a seal structure was assessed by a cross-sectional analysis and evaluation of the coating microstructure. Additionally; the microhardness test was performed to estimate coating fracture toughness; and Object-Oriented Finite Element analysis was used to assess its thermo-mechanical performance. The concept proposed in this study should be further validated to develop the most capable innovative technology for advanced gas turbine abradable seal structures.

Design of Ribbed Concrete Approach Slab Based on Interaction with the Embankment

2005 ◽  
Vol 1936 (1) ◽  
pp. 181-191 ◽  
Author(s):  
X. M. Shi ◽  
C. S. Cai ◽  
George Voyiadjis ◽  
Zhongjie Zhang
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Structural Performance ◽  
Element Analysis ◽  
Design Engineers ◽  
Approach Slabs ◽  
Approach Slab ◽  
Beam Design ◽  
Three Dimensional Finite Element

To alleviate the “bump” problem at bridge ends, a ribbed concrete approach slab (similar to slab-on-beam bridge decks) was proposed in place of the pile–column-supported approach span or flat slab system. The effect of given embankment settlement on the structural performance of a ribbed concrete approach slab with a span length of 60 ft and a width of 40 ft was investigated. The approach slab was modeled as a ribbed slab with a beam spacing of 32, 16, and 12 ft. A three-dimensional finite element analysis was conducted to model the interaction between the approach slab and the embankment soil. Finite element modeling techniques that simulate the separation of the slab and soil provide information on the effect of the embankment settlement on structural performance and beam design. The predicted internal forces provide design engineers with a scientific basis to design the approach slab properly, considering different levels of embankment settlements. Current AASHTO code specifications do not provide guidelines to design approach slabs considering the embankment settlement.

An evaluation of simplified techniques for estimating three-dimensional undrained ground movements due to tunnelling in soft soils

1992 ◽  
Vol 29 (1) ◽  
pp. 39-52 ◽  
Author(s):  
R. K. Rowe ◽  
K. M. Lee
Keyword(s):  
Plane Strain ◽  
Deformation Behaviour ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Cumulative Probability ◽  
Element Analysis ◽  
Cross Sectional ◽  
Soft Soils ◽  
Longitudinal Plane ◽  
Stress Changes

A number of simplified approaches have been used by various researchers to estimate the three-dimensional stress changes and ground deformations due to shallow tunnels in soft soils. The effectiveness of these simplified analyses, such as (i) axisymmetric analysis, (ii) longitudinal plane strain analysis, and (iii) empirical cumulative probability distribution approach, has been examined by comparison of results with those from a full three-dimensional elastoplastic finite-element analysis. For tunnels located at shallow depths, axisymmetric analyses are generally found to be unable to predict the correct magnitude of displacement around a tunnel heading. However, the trend of the three-dimensional deformation behaviour near the tunnel heading can be reasonably approximated by the average of the normalized displacement curves predicted by the two axisymmetric assumptions as described in this paper. The three-dimensional distribution of the displacement near the ground surface, on the other hand, can be approximately predicted by the cumulative probability approach, provided that the three empirical parameters required by the equations are reasonably estimated. In this paper, these parameters were estimated from the result of a two-dimensional plane strain cross-sectional analysis. Finally, it was found that modelling of three-dimensional deformations by a longitudinal plane strain analysis did not give good results for the cases examined. Key words : tunnelling, soft ground, analysis.

scholarly journals A Comparative Study of the Performance of Slender Reinforced Concrete Columns with Different Cross-Sectional Shapes

Fibers ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 35
Author(s):  
Safaa Qays Abdualrahman ◽  
Alaa Hussein Al-Zuhairi
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Slenderness Ratio ◽  
Structural Performance ◽  
Element Analysis ◽  
Cross Sectional ◽  
Rc Structures ◽  
Section Size ◽  
Concentric Loading ◽  
Rectangular Columns

Most reinforced concrete (RC) structures are constructed with square/rectangular columns. The cross-section size of these types of columns is much larger than the thickness of their partitions. Therefore, parts of these columns are protruded out of the partitions. The emergence of columns edges out of the walls has some disadvantages. This limitation is difficult to be overcome with square or rectangular columns. To solve this problem, new types of RC columns called specially shaped reinforced concrete (SSRC) columns have been used as hidden columns. Besides, the use of SSRC columns provides many structural and architectural advantages as compared with rectangular columns. Therefore, this study was conducted to explain the structural performance of slender SSRC columns experimentally and numerically via nonlinear finite element analysis. The study is based on nine RC specimens tested up to failure, as well as eighteen finite element (FE) models analyzed by Abaqus soft wear program. The use of SSRC columns led to increase strength by about 12% and reduce deformations, especially with slenderness ratio more than 40 as compared with equivalent square-shaped columns. Two design formulas were proposed to determine the compressive strength of SSRC columns under concentric loading. The results obtained indicate a good structural performance of SSRC columns when compared with equivalent square-shaped columns.

Three-Dimensional Reconstruction of Three Real Roots Included Periodontal Ligament and Implant Study

2014 ◽  
Vol 575 ◽  
pp. 931-934
Author(s):  
Qi Wang ◽  
Ling Chen ◽  
Zhong Zhang ◽  
Xing Hua Niu
Keyword(s):  
Finite Element ◽  
Periodontal Ligament ◽  
Three Dimensional ◽  
Element Model ◽  
Imaging Method ◽  
Element Analysis ◽  
Cross Sectional ◽  
The Real ◽  
Engineering Software ◽  
Ct Data

To investigate the periodontal ligament contains the real root of the three model cases, a combination of different implant and tooth variation of the stress distribution for the subsequent three root implant biomechanics analysis provides digital models. Methods: Mimics and Geomagic reverse engineering software for digital imaging method to obtain CT data processing. And the use of UG assembled in ANSYS workbench in finite element analysis. Results: A consistent with the real situation of three tooth root finite element model which contains periodontal ligament, and found that with the dental implant junction with the cross-sectional area decreases, where the stress amplitude fluctuations increases.

scholarly journals An Analytical Formulation for the Lateral Support Stiffness of a Spatial Flexure Strip

2015 ◽  
Author(s):  
Marijn Nijenhuis ◽  
J. P. Meijaard ◽  
Just L. Herder ◽  
Shorya Awtar ◽  
Dannis M. Brouwer
Keyword(s):  
Three Dimensional ◽  
Beam Element ◽  
Element Analysis ◽  
Cross Sectional ◽  
Flexure Mechanism ◽  
Stiffness Properties ◽  
Spatial Beam ◽  
Discrete Nature ◽  
Stiffness Characteristics

A flexure strip has constraint characteristics, such as stiffness properties and error motions, that limit its performance as a basic constituent of flexure mechanisms. This paper presents a framework for modeling the deformation and stiffness characteristics of general three-dimensional flexure strips that exhibit bending, shear and torsion deformation. The formulation is based on a finite strain discrete spatial beam element with refinements to account for plate-like behavior due to constrained cross-sectional warping. This framework is suited for analytical calculations thanks to the accuracy of the beam element, while its discrete nature allows for easy implementation in numeric software to serve as calculation aid. As case study, a closed-form parametric analytical expression is derived for the lateral support stiffness of a parallel flexure mechanism. This captures the deteriorating support stiffness when the mechanism moves in the intended degree of freedom. By incorporating relevant geometric nonlinearities and a warping constraint stiffening factor, an accurate load-displacement and stiffness expression for the lateral support direction is obtained. This result is verified by nonlinear finite element analysis.

scholarly journals A Computational Approach to Model Interfacial Effects on the Mechanical Behavior of Knitted Textiles

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Dani Liu ◽  
Bahareh Shakibajahromi ◽  
Genevieve Dion ◽  
David Breen ◽  
Antonios Kontsos
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Mechanical Performance ◽  
Computational Cost ◽  
Three Dimensional ◽  
Finite Element Models ◽  
Element Analysis ◽  
Reduced Order ◽  
Interfacial Effects ◽  
Relative Contribution

The mechanical behavior of knitted textiles is simulated using finite element analysis (FEA). Given the strong coupling between geometrical and physical aspects that affect the behavior of this type of engineering materials, there are several challenges associated with the development of computational tools capable of enabling physics-based predictions, while keeping the associated computational cost appropriate for use within design optimization processes. In this context, this paper investigates the relative contribution of a number of computational factors to both local and global mechanical behavior of knitted textiles. Specifically, different yarn-to-yarn interaction definitions in three-dimensional (3D) finite element models are compared to explore their relative influence on kinematic features of knitted textiles' mechanical behavior. The relative motion between yarns identified by direct numerical simulations (DNS) is then used to construct reduced order models (ROMs), which are shown to be computationally more efficient and providing comparable predictions of the mechanical performance of knitted textiles that include interfacial effects between yarns.

Experimental Study and Finite Element Analysis on RPC Footwalk Braces

2006 ◽  
Vol 302-303 ◽  
pp. 713-719
Author(s):  
Zhi Gang Yan ◽  
Gui Ping Yan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Safety Margin ◽  
Experimental Results ◽  
Element Analysis ◽  
Three Dimensional Finite Element ◽  
Reactive Powder

In this paper, a series of Reactive powder concrete (RPC) footwalk braces without conventional steel bars are designed for the Qing-Zang railway. Experimental studies on the braces are conducted in order to test the mechanical character of the braces. Totally eight RPC footwalk braces are experimentally measured with static load. According to the analysis of the experimental results, the ratio of the crack load got from the experiment to the design load is 2.54 and the deflection ductile coefficient is 2.32. The experimental results show that the mechanical performance of RPC footwalk braces can satisfy the engineering requirements and there is enough safety margin for footwalk braces. A three-dimensional finite element analysis (FEA) is also carried out and the results of FEA are compared with that of the experiments. The results show that the FEA method can be used in designing the RPC footwalk braces.

scholarly journals Moa diet fits the bill: virtual reconstruction incorporating mummified remains and prediction of biomechanical performance in avian giants

2016 ◽  
Vol 283 (1822) ◽  
pp. 20152043 ◽  
Author(s):  
Marie R. G. Attard ◽  
Laura A. B. Wilson ◽  
Trevor H. Worthy ◽  
Paul Scofield ◽  
Peter Johnston ◽  
...  
Keyword(s):  
New Zealand ◽  
Mechanical Performance ◽  
Niche Partitioning ◽  
Three Dimensional ◽  
Feeding Strategies ◽  
Element Analysis ◽  
Feeding Mode ◽  
Interspecific Differences ◽  
Palaeoecological Reconstruction ◽  
Three Dimensional Finite Element

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowledge about niche partitioning, feeding mode and preference among moa species is limited, hampering palaeoecological reconstruction and evaluation of the impacts of their extinction on remnant native biota, or the viability of exotic species as proposed ecological ‘surrogates'. Here we apply three-dimensional finite-element analysis to compare the biomechanical performance of skulls from five of the six moa genera, and two extant ratites, to predict the range of moa feeding behaviours relative to each other and to living relatives. Mechanical performance during biting was compared using simulations of the birds clipping twigs based on muscle reconstruction of mummified moa remains. Other simulated food acquisition strategies included lateral shaking, pullback and dorsoventral movement of the skull. We found evidence for limited overlap in biomechanical performance between the extant emu ( Dromaius novaehollandiae ) and extinct upland moa ( Megalapteryx didinus ) based on similarities in mandibular stress distribution in two loading cases, but overall our findings suggest that moa species exploited their habitats in different ways, relative to both each other and extant ratites. The broad range of feeding strategies used by moa, as inferred from interspecific differences in biomechanical performance of the skull, provides insight into mechanisms that facilitated high diversities of these avian herbivores in prehistoric New Zealand.

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