scholarly journals Predicting consolidation-induced wrinkles and their effects on composites structural performance

2019 ◽  
Vol 13 (6) ◽  
pp. 907-921 ◽  
Author(s):  
Balazs Varkonyi ◽  
Jonathan P.-H. Belnoue ◽  
James Kratz ◽  
Stephen R. Hallett
Keyword(s):  
High Performance ◽  
State Of The Art ◽  
Fibre Orientation ◽  
Structural Performance ◽  
Consolidation Process ◽  
Simulation Tools ◽  
Model Predictions ◽  
Out Of Plane ◽  
High Performance Composite ◽  
Strength And Deformation

AbstractThe majority of high-performance composite parts are nowadays designed using advanced numerical simulations that are able to accurately predict a part’s strength and deformation, providing that the internal ply architecture and exact fibre orientation are known with sufficient accuracy. However, most parts have some deviation of the fibre orientation from the ‘as-designed’ geometry, leading to the simulation overestimating the component’s strength. Up until recently, the advancement of the process simulation tools has not been sufficient to allow knowledge of this fibre deviation before any part has been manufactured, thus leading to overly conservative designs and costly experimental optimisation of the manufacturing process to reduce fibre path defects. This results in additional cost, waste of material and increased fuel consumption (due to the unnecessary weight of the components). This paper shows how state-of-the-art composite manufacturing simulations of the autoclave consolidation process can predict and help to mitigate against out-of-plane wrinkle formation in components made from toughened UD prepregs and thus raise confidence in failure analyses predictions. The industry relevant case of a stepped laminate is used as an example. Model predictions for the internal ply geometries are quantitatively compared to micrograph images of real samples. It is then shown how the input of the simulated ply architecture helps improving the accuracy of the failure simulations.

scholarly journals Predicting strength of Finnish birch veneers based on three different failure criteria

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Maximilian Pramreiter ◽  
Sabine C. Bodner ◽  
Jozef Keckes ◽  
Alexander Stadlmann ◽  
Florian Feist ◽  
...  
Keyword(s):  
High Performance ◽  
Fibre Orientation ◽  
Pearson Correlation ◽  
Failure Criteria ◽  
Reinforced Composites ◽  
Threshold Values ◽  
X Ray Scattering ◽  
Out Of Plane ◽  
Actual Strength ◽  
Fibre Reinforced Composites

Abstract The use of wood in high-performance composites based on laminated veneer products, plywood or wood hybrid elements thereof requires accurate prediction of strength of each individual ply. Previous research has shown that one dominating factor influencing the strength of birch veneers is the fibre orientation. The present study investigates the validity of the failure criteria after Tsai-Hill, Hoffmann and Kollmann for thin birch veneers under tensile loading. The fibre orientation in- and out-of-plane was measured by means of wide-angle X-ray scattering. Tensile strength and threshold values were determined in laboratory experiments. Pearson correlation between the predicted strength and actual strength ranged from 0.836 up to 0.883. Best correlation (r = 0.883) was achieved for Kollmann using a combined angle between in- and out-of-plane fibre orientation. It was shown that the failure criteria commonly used for manmade fibre reinforced composites are also applicable for thin birch veneers.

scholarly journals Experimental investigation of the behaviour of Unreinforced Masonry strengthened with UHPFRC

2019 ◽  
Author(s):  
Andreas P. Lampropoulos ◽  
Neil Maisuria ◽  
Ourania T. Tsioulou
Keyword(s):  
Experimental Investigation ◽  
High Performance ◽  
Unreinforced Masonry ◽  
Structural Performance ◽  
Fibre Reinforcement ◽  
New Materials ◽  
Reinforced Polymers ◽  
The Poor ◽  
Out Of Plane ◽  
High Performance Fibre

<p>The majority of existing Unreinforced Masonry (URM) structures are prone to weathering and catastrophic events such as earthquakes. The repair and strengthening of unreinforced masonry is a challenging task mainly due to the poor connection between the new materials and the existing substrate. The applications of Fibre Reinforced Polymers (FRP) for the strengthening of URM show that premature de-bonding and failure of the strengthened elements may occur.</p><p>In the current study, the application of Ultra High Performance Fibre Reinforcement Concrete (UHPFRC) layers for the improvement of the structural performance of URM specimens made of engineering bricks has been examined. Different percentages of steel fibres have been used and layers have been cast in connection with the URM specimens. Additional provisions for the improvement of the connection between the UHPFRC and the bricks have also been examined. The effect of the thickness of the layers and the effect of the fibre percentage of the UHPFRC have been investigated via flexural out of plane tests. The load mid- span deflection results have been recorded alongside with the slip at the UHPFRC-to-bricks interface and the results show that the structural performance of the URM specimens can be significantly improved with the proposed technique.</p>

Câbles à base de fibres pour la précontrainte

1992 ◽  
Vol 19 (1) ◽  
pp. 68-77
Author(s):  
A. Chabert ◽  
A. Picard
Keyword(s):  
Composite Materials ◽  
Automobile Industry ◽  
High Performance ◽  
Structural Engineering ◽  
State Of The Art ◽  
Aircraft Industry ◽  
Advantages And Disadvantages ◽  
High Performance Composite ◽  
Materials Used ◽  
Made In

Successful use of high performance composite materials was first made in the aircraft industry and, to a lesser extent, in the automobile industry. The use of these materials in civil engineering is now a reality, particularly for prestressing applications. This state-of-the-art paper deals with composite materials used for cables. It describes the composition of fiber prestressing cables and presents their mechanical properties. The anchorages, the advantages and disadvantages of these cables, their field of applications, and three successful applications in structural engineering are also discussed. Key words: composite materials, prestressing, fiber cables, concrete.

Core Programs of High-Performance Composite Materials

1998 ◽  
Author(s):  
A. Crasto ◽  
D. Anderson ◽  
R. Esterline ◽  
K. Han ◽  
C. Hill
Keyword(s):  
Composite Materials ◽  
High Performance ◽  
High Performance Composite

scholarly journals Global optimization of an encapsulated Si/SiO$$_2$$ L3 cavity with a 43 million quality factor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. P. Vasco ◽  
V. Savona
Keyword(s):  
Global Optimization ◽  
Photonic Crystal ◽  
Quality Factor ◽  
State Of The Art ◽  
Optimization Strategy ◽  
High Quality ◽  
Optimal Value ◽  
Out Of Plane ◽  
Fabrication Tolerances ◽  
Structural Imperfections

AbstractWe optimize a silica-encapsulated silicon L3 photonic crystal cavity for ultra-high quality factor by means of a global optimization strategy, where the closest holes surrounding the cavity are varied to minimize out-of-plane losses. We find an optimal value of $$Q_c=4.33\times 10^7$$ Q c = 4.33 × 10 7 , which is predicted to be in the 2 million regime in presence of structural imperfections compatible with state-of-the-art silicon fabrication tolerances.

scholarly journals Study of the Physical Behavior of a New Composite Material Based on Fly Ash from the Combustion of Coal in an Ultra-Supercritical Thermal Power Plant

2021 ◽  
Vol 5 (6) ◽  
pp. 151
Author(s):  
Mustapha El Kanzaoui ◽  
Chouaib Ennawaoui ◽  
Saleh Eladaoui ◽  
Abdelowahed Hajjaji ◽  
Abdellah Guenbour ◽  
...  
Keyword(s):  
Composite Material ◽  
Fly Ash ◽  
Power Plant ◽  
High Performance ◽  
Thermal Power ◽  
Recovery Process ◽  
Industrial Wastes ◽  
Raw Material ◽  
Polymerization Reaction ◽  
High Performance Composite

Given the amount of industrial waste produced and collected in the world today, a recycling and recovery process is needed. The study carried out on this subject focuses on the valorization of one of these industrial wastes, namely the fly ash produced by an ultra-supercritical coal power plant. This paper describes the use and recovery of fly ash as a high percentage reinforcement for the development of a new high-performance composite material for use in various fields. The raw material, fly ash, comes from the staged combustion of coal, which occurs in the furnace of an ultra-supercritical boiler of a coal-fired power plant. Mechanical compression, thermal conductivity, and erosion tests are used to study the mechanical, thermal, and erosion behavior of this new composite material. The mineralogical and textural analyses of samples were characterized using Scanning Electron Microscopy (SEM). SEM confirmed the formation of a new composite by a polymerization reaction. The results obtained are very remarkable, with a high Young’s modulus and a criterion of insulation, which approves the presence of a potential to be exploited in the different fields of materials. In conclusion, the composite material presented in this study has great potential for building material and could represent interesting candidates for the smart city.

High-performance composite H-ZSM-5/alumina catalyst for the methanol-to-ethylene conversion

2021 ◽  
pp. 1-15
Author(s):  
Alexey A. Zhokh ◽  
Andrey I. Trypolskyi ◽  
Valentina I. Gritsenko ◽  
Tamila G. Serebrii ◽  
Peter E. Strizhak
Keyword(s):  
High Performance ◽  
Alumina Catalyst ◽  
Ethylene Conversion ◽  
High Performance Composite

scholarly journals Multiple objects tracking in the UAV system based on hierarchical deep high-resolution network

2021 ◽  
Author(s):  
Wei Huang ◽  
Xiaoshu Zhou ◽  
Mingchao Dong ◽  
Huaiyu Xu
Keyword(s):  
High Resolution ◽  
Object Tracking ◽  
High Performance ◽  
State Of The Art ◽  
Class Imbalance ◽  
Unified Framework ◽  
Multiple Objects ◽  
Tracking Process ◽  
Objects Tracking ◽  
Different Types

AbstractRobust and high-performance visual multi-object tracking is a big challenge in computer vision, especially in a drone scenario. In this paper, an online Multi-Object Tracking (MOT) approach in the UAV system is proposed to handle small target detections and class imbalance challenges, which integrates the merits of deep high-resolution representation network and data association method in a unified framework. Specifically, while applying tracking-by-detection architecture to our tracking framework, a Hierarchical Deep High-resolution network (HDHNet) is proposed, which encourages the model to handle different types and scales of targets, and extract more effective and comprehensive features during online learning. After that, the extracted features are fed into different prediction networks for interesting targets recognition. Besides, an adjustable fusion loss function is proposed by combining focal loss and GIoU loss to solve the problems of class imbalance and hard samples. During the tracking process, these detection results are applied to an improved DeepSORT MOT algorithm in each frame, which is available to make full use of the target appearance features to match one by one on a practical basis. The experimental results on the VisDrone2019 MOT benchmark show that the proposed UAV MOT system achieves the highest accuracy and the best robustness compared with state-of-the-art methods.

scholarly journals Direct laser additive manufacturing of high performance oxide ceramics: a state-of-the-art review

2021 ◽  
Author(s):  
Stefan Pfeiffer ◽  
Kevin Florio ◽  
Dario Puccio ◽  
Marco Grasso ◽  
Bianca Maria Colosimo ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
High Performance ◽  
State Of The Art ◽  
Oxide Ceramics ◽  
Laser Additive Manufacturing ◽  
Direct Laser
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