scholarly journals POLYCONIC COMPOSITE LATTICE PAYLOAD ADAPTER AND THE TECHNOLOGY OF ITS MANUFACTURE

2021 ◽  
pp. 52-55
Author(s):  
A. A. Skleznev ◽  
A. A. Babichev ◽  
V. N. Borisov
Keyword(s):  
Composite Materials ◽  
Computational Experiment ◽  
Existing Structures ◽  
Weight Saving ◽  
Strength And Stiffness ◽  
Composite Lattice

The paper proposes a variant of the design of an adapter for several payloads made of composite materials. A computational experiment was carried out using the FEM, a comparison with existing structures is made, and the technology for manufacturing of such structures is described. Significant weight saving of the adapter design is shown in comparison with existing analogs while maintaining the same strength and stiffness margins.

Yield Point Spectra for Seismic Design and Rehabilitation

2000 ◽  
Vol 16 (2) ◽  
pp. 317-335 ◽  
Author(s):  
Mark Aschheim ◽  
Edgar F. Black
Keyword(s):  
Yield Point ◽  
Seismic Design ◽  
Ground Motions ◽  
Existing Structures ◽  
Intuitive Appeal ◽  
Forward Directivity ◽  
Capacity Spectrum ◽  
Long Duration ◽  
Nonlinear Static ◽  
Strength And Stiffness

A new spectral representation of seismic demand is described for use in the seismic design of new structures and in the evaluation and rehabilitation of existing structures. Yield Point Spectra (YPS) retain the intuitive appeal of the Capacity Spectrum Method (Freeman 1978) and join the Nonlinear Static Procedures of FEMA 273/274 (1997) and ATC 40 (1996) for use in estimating displacement demands. YPS also may be used to establish admissible combinations of strength and stiffness for the design of new structures to limit system ductility and drift to arbitrary values. Graphical procedures allow admissible design regions to be established to satisfy multiple performance objectives. YPS computed for 15 ground motions classified as Short Duration, Long Duration, or as containing near-fault Forward Directivity pulses are presented for bilinear and stiffness-degrading hysteretic models.

scholarly journals Concrete columns confined with different composite materials

2018 ◽  
Vol 199 ◽  
pp. 09012 ◽  
Author(s):  
Jacopo Donnini ◽  
Valeria Corinaldesi
Keyword(s):  
Composite Materials ◽  
High Performance ◽  
Optimal Solution ◽  
Concrete Columns ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced Polymers ◽  
Vapor Permeability ◽  
Fiber Reinforced ◽  
Existing Structures ◽  
Low Performance

In the last decades, the need for upgrading, strengthening and retrofitting of existing concrete structures is rapidly growing. Composite materials showed to be an optimal solution to face this problem, combining high efficacy with low invasiveness. The use of Fiber Reinforced Polymers (FRP) to wrap concrete columns has been widely investigated and became a very successful method to improve their structural performances. However, it has been recognized that FRPs, due to the presence of an organic resin, have a few drawbacks, such as poor mechanical behavior at high temperatures, lack of vapor permeability and impossibility to be installed on wet surfaces. This experimental work aims to propose a comparison between three different innovative methods as possible strengthening solutions for existing concrete columns. The structural behavior of 20 reduced scale concrete columns, realized by using a low performance concrete, in order to reproduce the poor mechanical properties of existing structures, was investigated. Two unreinforced column were tested in compression as reference. Six of them where reinforced by applying an external layer of FRP, with different types of fabric reinforcement (made of carbon or PBO fibers). Six columns were reinforced by using the same fabrics coupled with an inorganic matrix (FRCM) instead of epoxy. Six other columns were reinforced by using a layer of High Performance Fiber Reinforced Concrete (HPFRC) of 3 cm thick. Experimental results have been analyzed and performance of the three reinforcement systems have been compared.

Comparison of New Zealand standards used for seismic design of concrete buildings

2009 ◽  
Vol 42 (3) ◽  
pp. 187-203 ◽  
Author(s):  
Richard Fenwick ◽  
Gregory MacRae
Keyword(s):  
New Zealand ◽  
Response Spectra ◽  
Lateral Force ◽  
Relative Strength ◽  
Background Information ◽  
Existing Structures ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Design Requirements ◽  
Strength And Stiffness

Major changes have occurred over the last six decades in New Zealand design codes for seismic resistance of structures. This paper describes the changes in the required design strengths, stiffness levels and capacity design provisions with particular reference to buildings where the lateral force resistance is provided by reinforced concrete moment resisting frames. It is shown that simple comparisons of response spectra and limiting inter-storey drifts can give misleading conclusions regarding relative strength and stiffness requirements unless allowance is made for many other interacting factors. To illustrate this, minimum design requirements defined in codes (or standards) over the last six decades are compared with the corresponding 2009 design requirements for regular buildings in which the lateral force resistance is provided by moment resisting frames. The approach that is described can be applied to other forms of structure. The paper is intended to provide background information for engineers planning to assess the need for seismic retrofit of existing buildings and to show the different factors which should to be considered in assessing existing structures against current design criteria.

The strength and stiffness of polymers

1970 ◽  
Vol 319 (1536) ◽  
pp. 127-136 ◽  
Keyword(s):  
Composite Materials ◽  
Small Proportion ◽  
Young Modulus ◽  
Polymeric Materials ◽  
Substantial Proportion ◽  
Full Extension ◽  
Low Modulus ◽  
Strength And Stiffness ◽  
High Degree ◽  
Long Chain

Fully alined long chain polymers would have a Young modulus in the alinement direction similar to that of steel. Practically available polymeric materials have moduli less than one-tenth, and usually less than one-fiftieth of this, even with a high degree of molecular alinement. The paradox is of course resolved in principle by recognizing the predominance of chain folding in polymer crystallization, which allows strong alinement to occur with little or no extended chain continuity in the alinement direction. Questions which arise from this are: (1) what are the actual mechanisms of compliance in the material of relatively low modulus? and (2) by what means may it be possible to achieve full extension and alinement of a high proportion of the chains? Some tentative answers can be given in the light of current researches. Fully extended alinement for a small proportion is obtainable. Extension of a substantial proportion, rather than all, is the desideratum, since the folded chains con­tribute toughness. It can be useful to think of polymers as intrinsically composite materials, even when chemically homogeneous.

scholarly journals RILEM TC "Reinforcement of Timber Elements in Existing Structures"

2013 ◽  
Vol 778 ◽  
pp. 1041-1048 ◽  
Author(s):  
Thomas Tannert ◽  
Jorge M. Branco ◽  
Mariapaola Riggio
Keyword(s):  
Adhesive Layer ◽  
Technical Committee ◽  
Structural Performance ◽  
Rilem Technical Committee ◽  
Reinforced Polymers ◽  
Existing Structures ◽  
University Of Applied Sciences ◽  
Recent Developments ◽  
Strength And Stiffness ◽  
The University

The paper reports on the activities of the RILEM technical committee Reinforcement of Timber Elements in Existing Structures. The main objective of the committee is to coordinate the efforts to improve the reinforcement practice of timber structural elements. Recent developments related to structural reinforcements can be grouped into three categories: (i) addition of new structural systems to support the existing structure; (ii) configuration of a composite system; and (iii) incorporation of elements to increase strength and stiffness. The paper specifically deals with research carried out at the Bern University of Applied Sciences Switzerland (BFH), the University of Minho Portugal (UniMinho), and the University of Trento Italy (UNITN). Research at BFH was devoted to improve the structural performance of rounded dovetail joints by means of different reinforcement methods: i) self-tapping screws, ii) adhesive layer, and iii) a combination of self-tapping screws and adhesive layer. Research at UNITN targeted the use of dry connections for timber-to-timber composites, specifically reversible reinforcement techniques aimed at increasing the load-bearing capacity and the bending stiffness of existing timber floors. At UniMinho, double span continuous glulam slabs were strengthened with fibre-reinforced-polymers. All three examples demonstrate the improved structural performance of timber elements after reinforcing them.

Evaluation of Dimple Treatment for GFRP/Metal Co-Cured Joint

2006 ◽  
Vol 326-328 ◽  
pp. 1729-1732 ◽  
Author(s):  
Roysuke Matsuzaki ◽  
Motoko Shibata ◽  
Akira Todoroki
Keyword(s):  
Composite Materials ◽  
Surface Treatment ◽  
Bonding Strength ◽  
Marine Structures ◽  
Chemical Surface ◽  
Specific Strength ◽  
High Bonding Strength ◽  
High Specific Strength ◽  
Adhesive Surface ◽  
Strength And Stiffness

Since composite materials have high specific strength and stiffness, they are used for many fields such as aerospace and marine structures. According to such utilities, joining method between composites and metals must be developed. In this study, dimple treatment is carried out as a new reinforcing method for FRP/metal co-cured joint. Dimple treatment is applied to the adhesive surface of metal so that resin of FRP permeates into dimples and the strength of joints increases. It is revealed that dimple treatment achieves as high bonding strength as chemical surface treatment.

scholarly journals Composite materials based on natural fibres applied for structural reinforcement

2022 ◽  
Vol 960 (1) ◽  
pp. 012007
Author(s):  
G Bou Abdallah ◽  
I Ivanova ◽  
J Assih ◽  
C Diagana ◽  
D Dontchev
Keyword(s):  
Composite Materials ◽  
Rapid Development ◽  
Weight Ratio ◽  
High Strength ◽  
Natural Fibre ◽  
Natural Fibres ◽  
Experimental Program ◽  
Existing Structures ◽  
Structural Reinforcement ◽  
External Reinforcement

Abstract Environmental problems and environmental protection triggered a rapid development of natural fibres as sustainable materials for the reinforcement of reinforced concrete structures. Synthetic fibre polymer composite materials have been widely accepted by the construction industries as an effective external reinforcement material to rehabilitate deficiencies in existing structures. These materials have exceptional performance such as high strength to weight ratio, corrosion resistance and lightness. However, the disadvantages include high costs during manufacturing and end-of-life services, less environmentally friendly and causing adverse effects on human health. This article presents an experimental program on the use of natural fibres as reinforcement in composite materials for structural strengthening. Different types of natural fibre fabrics (hemp, flax, mixed hemp and cotton) in terms of their mechanical properties were studied. The fibre and fibre fabric sheets were tested in tension test and compared with carbon and glass fibre fabric sheet as reference. So, this study carries out the effect of natural hemp and flax fibre fabric thickness on ultimate loads of specimens. In addition, the ultimate load and stiffness of strengthened beams were investigated. In fact, the results show that the reinforcement technique allows to increase the load-bearing of strengthened structure by 8% to 35% in bending tests.

scholarly journals Analysis on Al6061-NI-graphite composite using squeeze casting method

2018 ◽  
Vol 7 (3.3) ◽  
pp. 303
Author(s):  
S Arunkumar ◽  
M Chandrasekaran ◽  
T Vinod Kumar ◽  
. .
Keyword(s):  
Composite Materials ◽  
Squeeze Casting ◽  
Applied Pressure ◽  
High Strength ◽  
Casting Process ◽  
Transfer Coefficients ◽  
Solidification Temperature ◽  
Graphite Composite ◽  
Heat Transfer Coefficients ◽  
Strength And Stiffness

In recent years, aluminum based composites have gained popularity in all the popularity in all emerging fields of technology owing to their superior stiffness and strength. This is because of the less wetting nature between the fortification and the framework and the difficulty of higher level of support expansion in to the grid. Notwithstanding, metal covered fortifications have possessed the capacity to beat these confinements to an exceptionally degree. NCG particles strengthened Al6061 network with different weight rates were manufactured by crush throwing strategy. The main advantages of composite materials are their high strength and stiffness, combined with low density, when compared with bulk materials, sanctioning for a weight reduction in the culminated part.Aluminium based composite materials are leading ones in this area; they are fabricated using many methods, including squeeze casting pro-cesses. Squeeze casting makes materials properties relatively easy to control by mixing materials with different properties in various propor-tion. Samples of [5] and 10-wtpercentage reinforcement additament were synthesized and characterized. Heat transfer coefficients during squeeze cast of commercial aluminium were determined, by using the solidification temperature versus time curves obtain for varying applied pressure during squeeze casting process. 

scholarly journals Aerospace Industry and Aluminum Metal Matrix Composites

2021 ◽  
Vol vm02 (is02) ◽  
pp. 73-81
Author(s):  
Sevim Yolcular Karaoglu ◽  
Serdar Karaoglu ◽  
Imgesu Unal
Keyword(s):  
Composite Materials ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Aerospace Industry ◽  
High Strength ◽  
Mechanical And Thermal Properties ◽  
Matrix Composites ◽  
Aluminum Metal ◽  
Strength And Stiffness ◽  
Aluminum Metal Matrix Composites

Researchers have turned to search for new materials that will meet all the aerospace industry requirements. When it is almost impossible to achieve this with a single material, composite materials have been studied, and there have been great developments in this field. Many elements are used in aircraft construction, but aluminum is the most preferred due to its low density, good castability, high strength, corrosion resistance, and good fatigue strength. However, its strength and stiffness limit its usability. To solve this problem, aluminum is combined with various elements. Aluminum metal matrix composites are an example of this. Aluminum metal matrix composites are preferred in aircraft applications due to their high specific modulus and good mechanical and thermal properties. This review provides information on the use of aluminum metal matrix composite materials in the aerospace industry.

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