Stress analysis of finite orthotropic composite containing an elliptical hole

2021 ◽  
pp. 002199832110507
Author(s):  
Narin S. Fatima ◽  
Robert E. Rowlands
Keyword(s):  
Composite Structures ◽  
Elliptical Hole ◽  
External Loading ◽  
Finite Geometries ◽  
Orthotropic Composites ◽  
Numerical Tools ◽  
Design Type ◽  
Measured Displacement ◽  
Type Information ◽  
Important Design

Although the mechanical integrity of a member can be highly influenced by associated stresses, determining the latter can be very challenging for finite orthotropic composites containing cutouts. This is particularly so if the external loading is not well known, a common situation in practical situations. Acknowledging the above, a finite elliptically-perforated orthotropic tensile laminate is stress analyzed by combining measured displacement data with relevant analytical and numerical tools. Knowledge of the external loading is unnecessary. Results are verified independently and the concepts are applicable to other situations. The developed technology can provide important design-type information for orthotropic composites. In particular, the ability to apply analyses for perforated composite structures which assume infinite geometry to finite geometries is demonstrated.

Surface effect on deformation around an elliptical hole by surface energy density theory

2019 ◽  
Vol 25 (2) ◽  
pp. 337-347
Author(s):  
Liyuan Wang
Keyword(s):  
Energy Density ◽  
Surface Energy ◽  
Hoop Stress ◽  
Surface Effect ◽  
Plane Deformation ◽  
Surface Elasticity ◽  
Closed Form Solution ◽  
Elliptical Hole ◽  
External Loading ◽  
Surface Energy Density

The finite plane deformation of nanomaterial surrounding an elliptical hole subjected to remote loading is systematically investigated using a recently developed continuum theory. A complex variable formulation is utilized to obtain a closed-form solution for the hoop stress along the edge of the hole. The results show that when the size of the hole reduces to the same order as the ratio of the surface energy density to the applied remote stress, the influence of the surface energy density plays an even more significant role, and the shape of the hole coupled with surface energy density has a significant effect on the elastic state around the hole. Surprisingly, in the absence of any external loading, the hoop stress induced solely by surface effects is identical to that for a hole with surface energy in a linearly elastic solid derived by the Gurtin–Murdoch surface elasticity model. The results in this paper should be useful for the precise design of nanodevices and helpful for the reasonable assessment of test results of nano-instruments.

scholarly journals Smart numerical tools for the modelling of ultrasonic testing on curved composite structures

2019 ◽  
Author(s):  
Alexandre Imperiale ◽  
Edouard Demaldent ◽  
Nicolas Leymarie ◽  
Sylvain Chatillon ◽  
Pierre Calmon
Keyword(s):  
Ultrasonic Testing ◽  
Composite Structures ◽  
Numerical Tools

scholarly journals Multilayer stag beetle elytra perform better under external loading via non-symmetric bending properties

2018 ◽  
Vol 15 (144) ◽  
pp. 20180427 ◽  
Author(s):  
Lakshminath Kundanati ◽  
Stefano Signetti ◽  
Himadri S. Gupta ◽  
Michele Menegon ◽  
Nicola M. Pugno
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behaviour ◽  
Composite Structures ◽  
Flexural Modulus ◽  
Bottom Layer ◽  
Multilayered Structure ◽  
External Loading ◽  
Multifunctional Composites ◽  
Bending Properties ◽  
Beetle Elytra

Insect cuticle has drawn a lot of attention from engineers because of its multifunctional role in the life of insects. Some of these cuticles have an optimal combination of lightweight and good mechanical properties, and have inspired the design of composites with novel microstructures. Among these, beetle elytra have been explored extensively for their multilayered structure, multifunctional roles and mechanical properties. In this study, we investigated the bending properties of elytra by simulating their natural loading condition and comparing it with other loading configurations. Further, we examined the properties of their constitutive bulk layers to understand the contribution of each one to the overall mechanical behaviour. Our results showed that elytra are graded, multilayered composite structures that perform better in natural loading direction in terms of both flexural modulus and strength which is likely an adaptation to withstand loads encountered in the habitat. Experiments are supported by analytical calculations and finite element method modelling, which highlighted the additional role of the relatively stiff external exocuticle and of the flexible thin bottom layer in enhancing flexural mechanical properties. Such studies contribute to the knowledge of the mechanical behaviour of this natural composite material and to the development of novel bioinspired multifunctional composites and for optimized armours.

Wave propagation in composite structures

2009 ◽  
Vol 225 (3) ◽  
pp. 639-648
Author(s):  
O Bareille ◽  
M N Ichchou
Keyword(s):  
Numerical Method ◽  
Composite Structures ◽  
Wave Number ◽  
Sandwich Composite ◽  
Flexural Wave ◽  
Honeycomb Core ◽  
Matching Criterion ◽  
Wave Numbers ◽  
Identification Technique ◽  
Measured Displacement

Dynamic behaviour of honeycomb-core composite structures forms the framework of this article. The wave numbers of propagative waves are the elements of comparison between a numerical method (wave finite-element method) and an experimental identification technique (inhomogeneous wave correlation). The numerical method is based on the description of the dynamics of periodic waveguides. The experimental technique uses a matching criterion with the measured displacement field to obtain the corresponding wave numbers for a wave-based description of the displacement. Both approaches are applied to a sandwich composite beam with a honeycomb core. They seem to be in quite good accordance with analytical results for the flexural wave number.

scholarly journals Applications, behaviour and construction of high performance steels in steel-concrete composite structures

2018 ◽  
Author(s):  
Brian Uy
Keyword(s):  
Composite Structures ◽  
High Performance ◽  
High Strength ◽  
International Standards ◽  
Design Parameters ◽  
Future Research ◽  
Building Structures ◽  
Design Procedures ◽  
Bridge Structures ◽  
Important Design

This paper addresses the applications, behaviour and construction of high performance steels in steel-concrete composite structures.   For the purposes of this paper, high performance steels will include high strength, stainless and weathering steels. Akin to many innovations in the construction industry, high performance steels have generally been adopted for the use in iconic projects well before design procedures have been developed in standards.  This paper will provide a summary of many of the applications particularly as they pertain to iconic projects in Australasia and internationally.   Recent research in these areas will also be summarised and important design parameters as they deviate from traditional mild structural steel will be highlighted.   Australasian advances in the standardisation of both bridges and buildings incorporating high performance steels will also be summarised, with particular reference to the Australasian Design Codes in Bridge Structures, ASNZS 5100 Part 6; and Building Structures ASNZS 2327 which have both been published in 2017.   The paper will conclude with suggestions for further research and will identify areas of significant gaps in Australasian and international standards which will also guide future research in this area.

A New Trefftz Based Finite Element for Static Analysis of Laminated Composite Structures

2019 ◽  
Author(s):  
Subhasankar Dwibedi
Keyword(s):  
Finite Element ◽  
Composite Materials ◽  
Composite Structures ◽  
Laminated Composite ◽  
Bench Mark ◽  
Element Analysis ◽  
Laminated Composite Structures ◽  
Element Approach ◽  
Numerical Tools ◽  
Trefftz Finite Element

Abstract Composite materials have been widely used in industries for several years owing to their capability to perform better than homogeneous isotropic materials. Numerical tools like finite element method are efficiently used for analysis of structures made of composite materials. However, for complex shapes or geometries of structures, it becomes uneconomical (computational resource wise) to use Rayleigh-Ritz based finite element analysis. An unique Trefftz based finite element has been developed in this article to efficiently fill the gap in the above mentioned scenario. Hybrid-Tefftz finite element method’s flexibility to use arbitrary shaped elements comes handy in modelling complex geometries. The developed hybrid-Trefftz finite element approach has been used on symmetric angle-ply laminated composite plate and the obtained results have been compared with bench mark solutions. The present method proposes an approach for development of hybrid-Trefftz type finite elements, by which analysis of antisymmetric structures is also possible, an area of research which has been less explored by such approach as revealed from survey of available open literature.

scholarly journals Solid Truss to Shell Numerical Homogenization of Prefabricated Composite Slabs

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4120
Author(s):  
Natalia Staszak ◽  
Tomasz Garbowski ◽  
Anna Szymczak-Graczyk
Keyword(s):  
Composite Structures ◽  
Homogenization Method ◽  
Fe Model ◽  
Structural Elements ◽  
Numerical Homogenization ◽  
Single Plate ◽  
Energy Equivalence ◽  
Numerical Tools ◽  
Simplified Procedures ◽  
Excellent Tool

The need for quick and easy deflection calculations of various prefabricated slabs causes simplified procedures and numerical tools to be used more often. Modelling of full 3D finite element (FE) geometry of such plates is not only uneconomical but often requires the use of complex software and advanced numerical knowledge. Therefore, numerical homogenization is an excellent tool, which can be easily employed to simplify a model, especially when accurate modelling is not necessary. Homogenization allows for simplifying a computational model and replacing a complicated composite structure with a homogeneous plate. Here, a numerical homogenization method based on strain energy equivalence is derived. Based on the method proposed, the structure of the prefabricated concrete slabs reinforced with steel spatial trusses is homogenized to a single plate element with an effective stiffness. There is a complete equivalence between the full 3D FE model built with solid elements combined with truss structural elements and the simplified homogenized plate FE model. The method allows for the correct homogenization of any complex composite structures made of both solid and structural elements, without the need to perform advanced numerical analyses. The only requirement is a correctly formulated stiffness matrix of a representative volume element (RVE) and appropriate formulation of the transformation between kinematic constrains on the RVE boundary and generalized strains.

Structural-Acoustic Optimization of Laminated Composite Structures Based on Response Surfaces Method

2013 ◽  
Vol 645 ◽  
pp. 109-115
Author(s):  
Lu Yun Chen ◽  
Nian Yang ◽  
Yu Fang Zhang
Keyword(s):  
Composite Structures ◽  
Acoustic Radiation ◽  
Plate Theory ◽  
Latin Square ◽  
Laminated Composite ◽  
Response Surfaces ◽  
External Loading ◽  
Laminated Composite Structures ◽  
Sequence Parameters ◽  
Optimization Efficiency

Based on Mindlin first order shear effect plate theory, the structural-acoustic optimization of laminated composite structures under external loading was investigated. For improving the optimization efficiency, the response surfaces method (RSM) is introduced, and the uniform Latin square method was used to select the most appropriate sample points. In the end, taking the laminated composite plate acoustic radiation as an example, the mathematical model of structural structural-acoustic optimization is established. The results show that the acoustic radiation of laminated composite structures can be reduced by optimizing the stacking sequence parameters such as layers thickness and layers angle. The results prove the validity of the calculating ways.

Load Transfer Index for Composite Materials

2015 ◽  
Author(s):  
Qingguo Wang ◽  
Khashayar Pejhan ◽  
Christine Q. Wu ◽  
Igor Telichev
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Load Transfer ◽  
External Loading ◽  
Load Path ◽  
New Paradigm ◽  
Linear Elastic ◽  
Transfer Index ◽  
Fundamental Equations ◽  
Load Transfer Analysis

Load transfer analysis is a new paradigm for lightweight vehicle design. U* index has been proved to be an effective indicator for the load path. The U* theory indicates that the external loading mainly transfers through the parts with higher U* values in the structure. However, the fundamental equations of the theory are based on isotropic, homogenous, and linear elastic assumptions for the materials. Consequently, U* index is inadequate for composite materials which are increasingly used in automotive structures. In this study, a new load transfer index for composite structures, U*O, is proposed for the first time inspired by the basic U* theory. The U*O index considers the composite material as orthotropic instead of isotropic and eliminates the limitation of the basic U*. The effectiveness of the new U*O index on load path prediction is demonstrated by a case study for a general Graphite-epoxy lamina. The U*O index is capable to evaluate the accurate load path for the composite specimen. By contrast, the basic U* analysis shows the incorrect results.

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