scholarly journals Introduction to Macroscopic Optimal Design in the Mechanics of Composite Materials and Structures

2021 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Aleksander Muc
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Constitutive Relations ◽  
A Priori ◽  
Chemical Properties ◽  
Composite Plates ◽  
Failure Criteria ◽  
Lagrange Equations ◽  
Homogenization Methods ◽  
Mechanics Of Composite Materials

The main goal of building composite materials and structures is to provide appropriate a priori controlled physico-chemical properties. For this purpose, a strengthening is introduced that can bear loads higher than those borne by isotropic materials, improve creep resistance, etc. Composite materials can be designed in a different fashion to meet specific properties requirements.Nevertheless, it is necessary to be careful about the orientation, placement and sizes of different types of reinforcement. These issues should be solved by optimization, which, however, requires the construction of appropriate models. In the present paper we intend to discuss formulations of kinematic and constitutive relations and the possible application of homogenization methods. Then, 2D relations for multilayered composite plates and cylindrical shells are derived with the use of the Euler–Lagrange equations, through the application of the symbolic package Mathematica. The introduced form of the First-Ply-Failure criteria demonstrates the non-uniqueness in solutions and complications in searching for the global macroscopic optimal solutions. The information presented to readers is enriched by adding selected review papers, surveys and monographs in the area of composite structures.

scholarly journals PROGRESSIVE FAILURE ANALYSIS OF HELICOPTER ROTOR BLADE UNDER AEROELASTIC LOADING

Aviation ◽  
2020 ◽  
Vol 24 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Kamran Ahmad ◽  
Yasir Baig ◽  
Hammad Rahman ◽  
Hassan Junaid Hasham
Keyword(s):  
Failure Analysis ◽  
Composite Structures ◽  
Composite Laminate ◽  
Progressive Failure ◽  
Constitutive Relations ◽  
Metal Structure ◽  
Failure Criteria ◽  
Helicopter Rotor ◽  
Progressive Failure Analysis ◽  
Failure Location

Unlike metal structure, composite structures don’t give any clue till the fatal final collapse. The problem is more complicated when applied load on the structure is aeroelastic in nature. Under such loading, composite laminate experiences stresses. The first layer failure happens when stresses in the weakest ply exceed the allowable strength of the laminate. This initial layer-based failure changes overall material characteristics. It is important now to degrade the composite laminate characteristics for the subsequent failure prediction. The constitutive relations are required to be updated by the reduction in stiffness. The rest of the undamaged laminates continue to take the load till the updated strength is reached. In the present work, layer wise progressive failure analysis under aeroelastic loading has been performed by the inclusion of different failure criteria which allow for the identification of the location of the failure. ANSYS APDL environment has been used to model geometry of helicopter rotor. Under the loading conditions, stresses are calculated in the blade. Using stress tensor and failure criteria, failure location and modes have been predicted. It has been found that failure starts at higher speeds and failure starts from the root chord and tend towards the tip chord.

Experimental Investigation on Buckling Analysis of Woven Glass Fiber/Epoxy Laminated Composite Materials

2015 ◽  
Vol 766-767 ◽  
pp. 150-155
Author(s):  
S. Sivasaravanan ◽  
V.K. Bupesh Raja ◽  
Sathishkumar
Keyword(s):  
Composite Materials ◽  
Glass Fiber ◽  
Composite Structures ◽  
Impact Resistance ◽  
Laminated Composite ◽  
Composite Plates ◽  
Buckling Analysis ◽  
Structural Components ◽  
Laminated Composite Materials ◽  
Woven Glass Fiber

The structural components made from the composite materials possess outstanding advantages like reliable mechanical properties, durability, and good corrosion resistance, and low density. They also exhibit high impact resistance and good damage tolerance. These merits of composite structures draw the attention of scientists, engineers and researchers in generally the stability of composite structures is verified by carrying out buckling analysis. The aircraft components are made up of laminated composite plates are subjected to buckling analysis, in order to confirm whether the component withstand the critical in plane loads. Composite structural plates provided with circular cut out, square cut out and rectangular cut-out are widely used as structural members in aircraft and vehicle design. The different holes are provided in these members can be access holes, pass-through holes for any hardware or holes for windows and doors. Sometimes these holes are produced for weight reduction in the composite structural components. In this present study, buckling experiments were carried out on Epoxy/woven glass fiber laminated composite plate specimens and the influence of different cut-out shapes like circular, square and rectangle are examined and determined experimentally. Boundary conditions free and clamped were considered for all the experiments. After the buckling experiments, comparisons were made between these two test results. These results show the effect of various cut-out shapes on the buckling load.

scholarly journals Progressive Damage Numerical Modelling and Simulation of Aircraft Composite Bolted Joints Bearing Response

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5606
Author(s):  
Guoqiang Gao ◽  
Luling An ◽  
Ioannis K. Giannopoulos ◽  
Ning Han ◽  
Ende Ge ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Composite Laminates ◽  
Composite Structures ◽  
Failure Modes ◽  
Composite Plates ◽  
Failure Criteria ◽  
Bolted Joints ◽  
Progressive Damage ◽  
User Input ◽  
Product Cycles

Finite element numerical progressive damage modelling and simulations applied to the strength prediction of airframe bolted joints on composite laminates can lead to shorter and more efficient product cycles in terms of design, analysis and certification, while benefiting the economic manufacturing of composite structures. In the study herein, experimental bolted joint bearing tests were carried out to study the strength and failure modes of fastened composite plates under static tensile loads. The experimental results were subsequently benchmarked against various progressive damage numerical modelling simulations where the effects of different failure criteria, damage variables and subroutines were considered. Evidence was produced that indicated that both the accuracy of the simulation results and the speed of calculation were affected by the choice of user input and numerical scheme.

Fracture Mechanics Approach for Analysis of Delamination in Composite Plates

2014 ◽  
Vol 969 ◽  
pp. 176-181 ◽  
Author(s):  
Milan Žmindák ◽  
Vladimir Dekýš ◽  
Pavol Novák
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Composite Structures ◽  
Ad Hoc ◽  
Failure Modes ◽  
Composite Plates ◽  
Failure Criteria ◽  
Fracture Data ◽  
Substantial Problem ◽  
Static Fracture

Delamination can be a substantial problem in designing composite structures. Modelling of delamination by finite element (FE) codes is limited. Previous efforts to model delamination and debonding failure modes using FE codes have typically relied on ad hoc failure criteria and quasi-static fracture data. Improvements to these modelling procedures can be made by using an approach based on fracture mechanics. A study of modelling delamination using the FE code ANSYS was conducted. This investigation demonstrates the modelling of composites through improved delamination modelling. Further developments to this approach may be improved.

scholarly journals Computational Modeling of Polymer Matrix Composites

2018 ◽  
Author(s):  
DC Pham
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Composite Materials ◽  
Polymer Matrix ◽  
Composite Structures ◽  
Computational Models ◽  
Polymer Matrix Composites ◽  
Failure Criteria ◽  
Matrix Composites ◽  
Stiffness Reduction

Applications of polymer matrix composites are growing in aerospace and offshore industries due to the light-weight and good mechanical properties of composite materials. The design of composite materials can be made at macroscopic level in which the composite mechanical properties can be tailored to offer the most desired performance of composite structures. Understanding on mechanical behavior of the composite material may require detailed investigations at the microscopic level involving the behaviour of the composite constituents such as the fiber, the polymer matrix and the fiber/matrix interface under macroscopic loads. Composite failure criteria are often employed to evaluate the failure of composite material and its constituents. Computational damage models can be then developed to reflect the stiffness reduction of the material once damage at the macro- and micro- scales of the composite is indicated. The successful prediction of composite structures relies on consistent computational models which can capture the mechanical behaviour of composite materials at different length scales.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

scholarly journals Defects and uncertainties of adhesively bonded composite joints

2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Sadik Omairey ◽  
Nithin Jayasree ◽  
Mihalis Kazilas
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Production Efficiency ◽  
Adhesive Bonding ◽  
Detection Methods ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Wide Range ◽  
Bonded Composite

AbstractThe increasing use of fibre reinforced polymer composite materials in a wide range of applications increases the use of similar and dissimilar joints. Traditional joining methods such as welding, mechanical fastening and riveting are challenging in composites due to their material properties, heterogeneous nature, and layup configuration. Adhesive bonding allows flexibility in materials selection and offers improved production efficiency from product design and manufacture to final assembly, enabling cost reduction. However, the performance of adhesively bonded composite structures cannot be fully verified by inspection and testing due to the unforeseen nature of defects and manufacturing uncertainties presented in this joining method. These uncertainties can manifest as kissing bonds, porosity and voids in the adhesive. As a result, the use of adhesively bonded joints is often constrained by conservative certification requirements, limiting the potential of composite materials in weight reduction, cost-saving, and performance. There is a need to identify these uncertainties and understand their effect when designing these adhesively bonded joints. This article aims to report and categorise these uncertainties, offering the reader a reliable and inclusive source to conduct further research, such as the development of probabilistic reliability-based design optimisation, sensitivity analysis, defect detection methods and process development.

The effect of nanoparticle additive on surface milling in glass fiber reinforced composite structures

2021 ◽  
pp. 096739112110141
Author(s):  
Ferhat Ceritbinmez ◽  
Ahmet Yapici ◽  
Erdoğan Kanca
Keyword(s):  
Composite Materials ◽  
Glass Fiber ◽  
Composite Structures ◽  
Fiber Composite ◽  
Cutting Speed ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Glass Fiber Reinforced ◽  
Composite Layers

In this study, the effect of adding nanosize additive to glass fiber reinforced composite plates on mechanical properties and surface milling was investigated. In the light of the investigations, with the addition of MWCNTs additive in the composite production, the strength of the material has been changed and the more durable composite materials have been obtained. Slots were opened with different cutting speed and feed rate parameters to the composite layers. Surface roughness of the composite layers and slot size were examined and also abrasions of cutting tools used in cutting process were determined. It was observed that the addition of nanoparticles to the laminated glass fiber composite materials played an effective role in the strength of the material and caused cutting tool wear.

Failure Analysis of Composite Structures Using Multiscale Technique

2020 ◽  
Vol 995 ◽  
pp. 209-213
Author(s):  
Young W. Kwon
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Cell Model ◽  
Fibrous Composite ◽  
Failure Criteria ◽  
Multiscale Approach ◽  
Interface Failure ◽  
Fiber Failure ◽  
Strain Rate Effects ◽  
Constituent Material

Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.

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