scholarly journals Structural Analysis of Composite Conical Convex-Concave Plate (CCCP) Using VAM-Based Equivalent Model

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2012
Author(s):  
Qingshan Yi ◽  
Yifeng Zhong ◽  
Zheng Shi
Keyword(s):  
Present Model ◽  
Natural Frequencies ◽  
Material Selection ◽  
Structural Parameters ◽  
Unit Cell ◽  
Geometric Parameters ◽  
Equivalent Model ◽  
Design Stage ◽  
3D Fem ◽  
Trade Offs

Compared with the ordinary foundation plate, the composite conical convex-concave plate (CCCP) has obvious anisotropic characteristics, and there is less research on the relationship between its mechanical properties and structural parameters. In this article, a numerical model for the equivalent stiffness of a typical unit cell with conical convex is established by using the variational asymptotic method. Then, the 3D finite element model (3D-FEM) of CCCP is transformed into 2D equivalent plate model (2D-EPM) with the effective plate properties obtained from the constitutive analysis of unit cell. The accuracy of 2D-EPM is verified by comparing with the displacement, natural frequencies, and buckling results from 3D-FEM under different boundary conditions. Then, the influence of geometric parameters and layup configurations on the effective performances of CCCP are investigated. Finally, the buckling loads and natural frequencies of bidirectional CCCP are compared with those of CCCP by using the present model. The present model is particularly useful in the early design stage of CCCP where many design trade-offs need to be made over a vast design space in terms of material selection, ply angles, and geometric parameters.

scholarly journals Prediction of Bending, Buckling and Free-Vibration Behaviors of 3D Textile Composite Plates by Using VAM-Based Equivalent Model

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 134
Author(s):  
Senbiao Xi ◽  
Yifeng Zhong ◽  
Zheng Shi ◽  
Qingshan Yi
Keyword(s):  
Free Vibration ◽  
Composite Plate ◽  
Three Dimensional ◽  
Composite Plates ◽  
Unit Cell ◽  
Equivalent Model ◽  
Fe Model ◽  
Equivalent Stiffness ◽  
Textile Composite ◽  
3D Fem

To solve the microstructure-related complexity of a three-dimensional textile composite, a novel equivalent model was established based on the variational asymptotic method. The constitutive modeling of 3D unit cell within the plate was performed to obtain the equivalent stiffness, which can be inputted into the 2D equivalent model (2D-EPM) to perform the bending, free-vibration and buckling analysis. The correctness and effectiveness of the 2D-EPM was validated by comparing with the results from 3D FE model (3D-FEM) under various conditions. The influence of yarn width and spacing on the equivalent stiffness was also discussed. Finally, the effective performances of 3D textile composite plate and 2D plain-woven laminate with the same thickness and yarn content were compared. The results revealed that the bending, buckling and free-vibration behaviors predicted by 2D-EPM were in good agreement with 3D-FEM, and the local field distributions within the unit cell of 3D textile composite plate were well captured. Compared with the 2D plain-woven laminate, the displacement of 3D textile composite plate was relatively larger under the uniform load, which may due to the fact that the through-the-thickness constrains of the former are only dependent on the binder yarns, while the warp yarns and weft yarns of the latter are intertwined closely.

scholarly journals Thermo-Viscoelastic Response of 3D Braided Composites Based on a Novel FsMsFE Method

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 271
Author(s):  
Jun-Jun Zhai ◽  
Xiang-Xia Kong ◽  
Lu-Chen Wang
Keyword(s):  
Finite Element ◽  
Cell Model ◽  
Structural Parameters ◽  
Thermal Relaxation ◽  
Viscoelastic Behavior ◽  
Unit Cell ◽  
Time Dependent ◽  
3D Braided Composites ◽  
Equivalent Time ◽  
Representative Unit Cell

A homogenization-based five-step multi-scale finite element (FsMsFE) simulation framework is developed to describe the time-temperature-dependent viscoelastic behavior of 3D braided four-directional composites. The current analysis was performed via three-scale finite element models, the fiber/matrix (microscopic) representative unit cell (RUC) model, the yarn/matrix (mesoscopic) representative unit cell model, and the macroscopic solid model with homogeneous property. Coupling the time-temperature equivalence principle, multi-phase finite element approach, Laplace transformation and Prony series fitting technology, the character of the stress relaxation behaviors at three scales subject to variation in temperature is investigated, and the equivalent time-dependent thermal expansion coefficients (TTEC), the equivalent time-dependent thermal relaxation modulus (TTRM) under micro-scale and meso-scale were predicted. Furthermore, the impacts of temperature, structural parameters and relaxation time on the time-dependent thermo-viscoelastic properties of 3D braided four-directional composites were studied.

scholarly journals Alternative Agri-Food Systems Under a Market Agencements Approach: The Case of Multifunctional Farming Activity in a Peri-Urban Area

Environments ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 61
Author(s):  
Maria Cecilia Mancini ◽  
Filippo Arfini ◽  
Federico Antonioli ◽  
Marianna Guareschi
Keyword(s):  
Urban Area ◽  
Food Systems ◽  
Food System ◽  
Large Body ◽  
Alternative Food ◽  
Design Stage ◽  
Alternative Food Networks ◽  
Alternative Food Systems ◽  
Design And Implementation ◽  
Trade Offs

(1) Background: A large body of literature is available on the environmental, social, and economic sustainability of alternative food systems, but not much of it is devoted to the dynamics underlying their design and implementation, more specifically the processes that make an alternative food system successful or not in terms of its sustainability aims. This gap seems to be particularly critical in studies concerning alternative food systems in urban and peri-urban agriculture (UPA). This paper explores how the design and implementation of multifunctional farming activity in a peri-urban area surrounding the city of Reggio Emilia in the Emilia-Romagna region of Italy impact the achievement of its sustainability aims. (2) Methods: The environmental, social, and economic components of this project are explored in light of the sociology of market agencements. This method brings up the motivations of the human entities involved in the project, the role played by nonhuman entities, and the technical devices used for the fulfillment of the project’s aims. (3) Results: The alternative food system under study lacked a robust design phase and a shared definition of the project aims among all the stakeholders involved. This ended in a substantial mismatch between project aims and consumer expectations. (4) Conclusions: When a comprehensive design stage is neglected, the threefold aim concerning sustainability might not be achievable. In particular, the design of alternative food systems must take into account the social environment where it is intended to be put in place, especially in UPA, where consumers often live in suburban neighborhoods wherein the sense of community is not strong, thus preventing them from getting involved in a community-based project. In such cases, hybridization can play a role in the sustainability of alternative food networks, provided that some trade-offs occur among the different components of sustainability—some components of sustainability will be fully achieved, while others will not.

scholarly journals Multi-Objective Optimization of Autonomous Microgrids with Reliability Consideration

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4466
Author(s):  
Maël Riou ◽  
Florian Dupriez-Robin ◽  
Dominique Grondin ◽  
Christophe Le Loup ◽  
Michel Benne ◽  
...  
Keyword(s):  
Power Systems ◽  
Rural Areas ◽  
Energy System ◽  
Design Stage ◽  
Multi Objective Optimization ◽  
Renewable Energy Resources ◽  
Nsga Ii ◽  
Renewable Integration ◽  
Multi Objective ◽  
Trade Offs

Microgrids operating on renewable energy resources have potential for powering rural areas located far from existing grid infrastructures. These small power systems typically host a hybrid energy system of diverse architecture and size. An effective integration of renewable energies resources requires careful design. Sizing methodologies often lack the consideration for reliability and this aspect is limited to power adequacy. There exists an inherent trade-off between renewable integration, cost, and reliability. To bridge this gap, a sizing methodology has been developed to perform multi-objective optimization, considering the three design objectives mentioned above. This method is based on the non-dominated sorting genetic algorithm (NSGA-II) that returns the set of optimal solutions under all objectives. This method aims to identify the trade-offs between renewable integration, reliability, and cost allowing to choose the adequate architecture and sizing accordingly. As a case study, we consider an autonomous microgrid, currently being installed in a rural area in Mali. The results show that increasing system reliability can be done at the least cost if carried out in the initial design stage.

scholarly journals Linear Structural Trends and Multi-Phase Intergrowths in Helvine-Group Minerals, (Zn,Fe,Mn)8[Be6Si6O24]S2

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 325
Author(s):  
Sytle Antao
Keyword(s):  
Cell Parameter ◽  
Structural Parameters ◽  
Unit Cell ◽  
Fluid Composition ◽  
Ternary Solid Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Difference ◽  
Multi Phase ◽  
And Diffusion

Synchrotron high-resolution powder X-ray diffraction (HRPXRD) and Rietveld structure refinements were used to examine the crystal structure of single phases and intergrowths (either two or three phases) in 13 samples of the helvine-group minerals, (Zn,Fe,Mn)8[Be6Si6O24]S2. The helvine structure was refined in the cubic space group P4¯3n. For the intergrowths, simultaneous refinements were carried out for each phase. The structural parameters for each phase in an intergrowth are only slightly different from each other. Each phase in an intergrowth has well-defined unit-cell and structural parameters that are significantly different from the three endmembers and these do not represent exsolution or immiscibility gaps in the ternary solid-solution series. The reason for the intergrowths in the helvine-group minerals is not clear considering the similar radii, identical charge, and diffusion among the interstitial M cations (Zn2+, Fe2+, and Mn2+) that are characteristic of elongated tetrahedral coordination. The difference between the radii of Zn2+ and Mn2+ cations is 10%. Depending on the availability of the M cations, intergrowths may occur as the temperature, pressure, fugacity fS2, and fluid composition change on crystallization. The Be–Si atoms are fully ordered. The Be–O and Si–O distances are nearly constant. Several structural parameters (Be–O–Si bridging angle, M–O, M–S, average <M–O/S>[4] distances, and TO4 rotational angles) vary linearly with the a unit-cell parameter across the series because of the size of the M cation.

Analysis of Modal Parameters of Adhesively Bonded Double-Strap Joints by the Modal Strain Energy Method

1993 ◽  
Author(s):  
Mohan D. Rao ◽  
Krishna M. Gorrepati
Keyword(s):  
Strain Energy ◽  
Natural Frequencies ◽  
Structural Parameters ◽  
Flexural Vibration ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Adhesively Bonded ◽  
Modal Strain Energy ◽  
Joint System ◽  
Damping Material

Abstract This paper presents the analysis of modal parameters (natural frequencies, damping ratios and mode shapes) of a simply supported beam with adhesively bonded double-strap joint by the finite-element based Modal Strain Energy (MSE) method using ANSYS 4.4A software. The results obtained by the MSE method are compared with closed form analytical solutions previously obtained by the first author for flexural vibration of the same system. Good agreement has been obtained between the two methods for both the natural frequencies and system loss factors. The effects of structural parameters and material properties of the adhesive on the modal properties of the joint system are also studied which are useful in the design of the joint system for passive vibration and noise control. In order to evaluate the MSE and analytical results, some experiments were conducted using aluminum double-strap joint with 3M ISD112 damping material. The experimental results agreed well with both analytical and MSE results indicating the validity of both analytical and MSE methods. Finally, a comparative study has been conducted using various commercially available damping materials to evaluate their relative merits for use in the design of these joints.

scholarly journals Ballistic Resistance of Honeycomb Sandwich Panels under In-Plane High-Velocity Impact

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Chang Qi ◽  
Shu Yang ◽  
Dong Wang ◽  
Li-Jun Yang
Keyword(s):  
Structural Parameters ◽  
Sandwich Panels ◽  
Unit Cell ◽  
Dynamic Responses ◽  
Honeycomb Core ◽  
Ballistic Resistance ◽  
Honeycomb Sandwich ◽  
Aluminum Honeycomb ◽  
Parametric Studies ◽  
Nonmonotonic Effects

The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson’s ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs.

Design and Analysis of a Miniaturization Nanoindentation and Scratch Device

2011 ◽  
Vol 314-316 ◽  
pp. 1792-1795
Author(s):  
Hu Huang ◽  
Hong Wei Zhao ◽  
Jie Yang ◽  
Shun Guang Wan ◽  
Jie Mi ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Amorphous Alloy ◽  
Natural Frequencies ◽  
Geometric Parameters ◽  
Flexure Hinge ◽  
Element Analysis ◽  
Modal Characteristics

In this paper, a miniaturization nanoindentation and scratch device was developed. Finite element analysis was carried out to study static and modal characteristics of x/y flexure hinge and z axis driving hinge as well as effect of geometric parameters on output performances of z axis driving hinge. Results indicated that x/y flexure hinge and z axis driving hinge had enough strength and high natural frequencies. Geometric parameters of z axis driving hinge affected output performances significantly. The model of developed device was established. Indentation experiments of Si and amorphous alloy showed that the developed miniaturization nanoindentation and scratch device worked well and can carry out indentation experiments with certain accuracy.

scholarly journals Knowledge translation of prediction rules: methods to help health professionals understand their trade-offs

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
K. Hemming ◽  
M. Taljaard
Keyword(s):  
Knowledge Translation ◽  
Health Professionals ◽  
Natural Frequencies ◽  
Prediction Models ◽  
Prediction Rule ◽  
Performance Measure ◽  
Essential Information ◽  
Prediction Rules ◽  
Cut Points ◽  
Trade Offs

AbstractClinical prediction models are developed with the ultimate aim of improving patient outcomes, and are often turned into prediction rules (e.g. classifying people as low/high risk using cut-points of predicted risk) at some point during the development stage. Prediction rules often have reasonable ability to either rule-in or rule-out disease (or another event), but rarely both. When a prediction model is intended to be used as a prediction rule, conveying its performance using the C-statistic, the most commonly reported model performance measure, does not provide information on the magnitude of the trade-offs. Yet, it is important that these trade-offs are clear, for example, to health professionals who might implement the prediction rule. This can be viewed as a form of knowledge translation. When communicating information on trade-offs to patients and the public there is a large body of evidence that indicates natural frequencies are most easily understood, and one particularly well-received way of depicting the natural frequency information is to use population diagrams. There is also evidence that health professionals benefit from information presented in this way.Here we illustrate how the implications of the trade-offs associated with prediction rules can be more readily appreciated when using natural frequencies. We recommend that the reporting of the performance of prediction rules should (1) present information using natural frequencies across a range of cut-points to inform the choice of plausible cut-points and (2) when the prediction rule is recommended for clinical use at a particular cut-point the implications of the trade-offs are communicated using population diagrams. Using two existing prediction rules, we illustrate how these methods offer a means of effectively and transparently communicating essential information about trade-offs associated with prediction rules.

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