Comparison of Natural Frequencies of Composite Cylindrical Shells: A Squared Lattice With Its Equivalent Seamless One

2010 ◽  
Author(s):  
M. H. Kargarnovin ◽  
J. E. Jam ◽  
A. H. Hashemian
Keyword(s):  
Composite Materials ◽  
Natural Frequency ◽  
Hollow Cylinder ◽  
Natural Frequencies ◽  
Outer Radius ◽  
Composite Cylinder ◽  
High Extent ◽  
Specific Strength ◽  
High Specific Strength ◽  
Strength And Stiffness

Modern Latticed composite materials whose high specific strength and stiffness are utilized in spacecraft and rocket structures to a sufficiently high extent are now widely used in primary airframe structures. In this work a comparison between squared latticed composite cylinder shells and the equivalent hollow cylinder with same weight, outer radius, length and material is done. An analytical equation is derived for natural frequency of square latticed composite shells. The first fifth modes are taken to be compared. The analytical and FEM results are shown and compared to each other. Also, as discussed, the squared lattice cylinder shell reaches to their natural frequencies easily than the equivalent hollow cylinder shell.

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.

Effect of Core Thickness and Intermediate Layers on Mechanical Properties of Polypropylene Honeycomb Multi-Layer Sandwich Structures

2014 ◽  
Vol 59 (1) ◽  
pp. 11-16 ◽  
Author(s):  
J. Arbaoui ◽  
Y. Schmitt ◽  
J.-L. Pierrot ◽  
F.-X. Royer
Keyword(s):  
Mechanical Properties ◽  
Sandwich Structures ◽  
Bending Test ◽  
Honeycomb Core ◽  
Lightweight Construction ◽  
Specific Strength ◽  
High Specific Strength ◽  
Intermediate Layers ◽  
Core Thickness ◽  
Strength And Stiffness

Abstract Sandwich structures are widely used in lightweight construction especially in aerospace industries because of their high specific strength and stiffness. This paper investigates the effect of core thickness and intermediate layers on the mechanical properties of a polypropylene honeycomb core/composite facing multilayer sandwich structure under three points bending. We developed a theoretical model which makes it possible to calculate the shear properties in multi-cores. The results obtained by this model are agreed with our experimental results, and the results obtained with bending test showed that the mechanical properties of the composite multilayer structures increase with core thickness and intermediate layers.

A Comparative Investigation on Foamability and Structure of Al Foams Added with Precipitator and Cenosphere Fly Ash Particles

2013 ◽  
Vol 652-654 ◽  
pp. 89-92
Author(s):  
Attanadol Prapajaraswong ◽  
Seksak Asavavisithchai
Keyword(s):  
Fly Ash ◽  
Comparative Investigation ◽  
Engineering Material ◽  
Foam Structure ◽  
Specific Strength ◽  
High Specific Strength ◽  
Large Expansion ◽  
Al Foam ◽  
Strength And Stiffness ◽  
Al Foams

Al foam is an advanced engineering material with many outstanding properties, such as very low density, high specific strength and stiffness, and large energy absorption. In the present study, pure Al foams were mixed with either cenosphere or precipitator fly ash particles of various contents. Fly ash particles are used in Al foams as reinforcement and stabilising materials which enable the foams with large expansion. It is found that Al foams with precipitator fly ash particles of various contents exhibited larger expansions than the foams with cenosphere fly ash particles. The quantitative analysis also revealed that more stable foam structure was obtained in Al foams with precipitator fly ash addition.

Influence of Pulsed Current on the Tensile Behaviors of the 5XXX Aluminum Alloy

2014 ◽  
Vol 709 ◽  
pp. 399-402
Author(s):  
Jung Han Song ◽  
Seo Gou Choi
Keyword(s):  
Flow Stress ◽  
Room Temperature ◽  
Test System ◽  
Al Alloys ◽  
Electric Resistivity ◽  
Al Alloy ◽  
Challenging Problem ◽  
Specific Strength ◽  
High Specific Strength ◽  
Strength And Stiffness

Aluminum (Al) alloys have great potential as ideal structural materials because of their high specific strength and stiffness. However, Al alloys exhibit poor ductility at room temperature. Enhancing the formability is a very important and challenging problem to both automotive and manufacturing engineers. In this study, the electro-plastic effects, which is first discovered in 1960s, of 5xxx Al alloy sheets are investigated to improve the formability. To begin with, a test system is built up to carry out the tensile test with heavy electric current flowing through the specimen. The evolutions of the flow stress and the electric resistivity are obtained using this test system. The significant decrease in the flow stress caused by the heavy flowing through current is observed.

scholarly journals Design and Experimental Investigation of Composite Automotive Drive Shaft

2021 ◽  
Vol 9 (10) ◽  
pp. 1088-1094
Author(s):  
Akshay Dudam
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Materials ◽  
Natural Frequency ◽  
Power Transmission ◽  
Drive Shaft ◽  
Torsional Buckling ◽  
Element Analysis ◽  
High Rotational Speed ◽  
Specific Strength

Abstract: Replacing composite bodies by the conventional metallic bodies have many advantages because of high specific strength and high specific stiffness of the composite materials. As compared to the conventional drive shafts, Composite drive shafts have the potential of lighter and longer life with high rotational speed. Nowadays drive shafts are used in two pieces. However, the main advantage of the current design is that only one piece of composite drive shaft is possible that fulfils all the drive shaft requirements. The torsional strength, torsional buckling and bending natural frequency are the main basic requirements considered here. This work is all about the replacing the conventional two-piece steel drive shaft with a one-piece carbon/epoxy. Design of composite drive shaft Classical Lamination Theory is used for the design of composite drive shaft. Finite element analysis (FEA) was used to design composite drive shafts incorporating carbon within an epoxy matrix. From experimental results, it was found that the developed one-piece automotive composite drive shaft had 64% mass reduction, 74% increase in torque capability compared with a conventional two-piece steel drive shaft. It also had 6380 rpm of natural frequency which was higher than the design specification of 3050 rpm. Index Terms: Bending frequency, Composite Materials, Drive shaft, Finite Element Analysis (FEA), Power transmission, Torsion, Torsional buckling.

The Second Century Papers: Looking Ahead in Aeronautics—6

1968 ◽  
Vol 72 (691) ◽  
pp. 557-566
Author(s):  
W. G. Molyneux
Keyword(s):  
Structural Analysis ◽  
Computer Technology ◽  
Second Century ◽  
Structural Form ◽  
Structural Geometry ◽  
Skin Structure ◽  
Specific Strength ◽  
High Specific Strength ◽  
Strength And Stiffness ◽  
Definition Of

Summary Developments in computer technology will result in a capacity for structural analysis and definition of structural geometry in intimate detail, and this capacity will be used to the full for design and fabrication in the relatively brittle materials of high specific strength and stiffness that will become commonplace. However, only evolutionary developments in basic structural form are anticipated for the future, with stressed-skin structure remaining dominant. The structure will be windowless. Mass-produced personal aircraft will be required for leisure purposes, and glass is likely to be a favoured structural material for these.

Application of Composites to Deepwater Top Tensioned Riser Systems

2002 ◽  
Author(s):  
Pascinthe Saad ◽  
Mamdouh M. Salama ◽  
Ove Jahnsen
Keyword(s):  
Composite Materials ◽  
Positive Impact ◽  
Substantial Reduction ◽  
Structural Damping ◽  
Field Development ◽  
Specific Strength ◽  
Structural Impact ◽  
Exploration And Production ◽  
Hydrostatic Stresses ◽  
Strength And Stiffness

As offshore exploration and production activities head to deeper water, extensive efforts have been focused on mitigating the potential challenges associated with deep- and ultra deep-water riser systems. Such challenges include overcoming the hydrostatic stresses associated with the increased length of water column as well as the increase in overall riser system weight. The implementation of composites in offshore applications is perceived as a promising path forward with composite materials offering many advantages including high specific strength and stiffness, lighter weight, enhanced corrosion resistance, high thermal insulation, improved structural damping and favorable fatigue performance characteristics. This paper focuses on evaluating the potential of composite materials for applications to deepwater top tensioned riser systems from the standpoint of possible impact on overall system cost and reliability. Many deepwater development concepts utilize top tensioned production riser systems, mainly, for conveying production fluids from the wellhead to the surface processing facilities in a dry tree based field development solution. Top tensioned risers can be configured as dual or single barrier systems and can either be hydraulically or hydro-pneumatically supported as on a typical TLP system or pneumatically supported through positively buoyant air cans as on a Spar riser system. Many advantages can be derived from the use of composites on buoyancy can systems. Such advantages include a reduced system weight, higher net lift, smaller diameter cans, improved efficiency and a positive impact on required inspection frequency. Main advantages of using composites for an entire TLP riser system include a significant reduction in both tension requirement and tensioner weight resulting in substantial reduction in total deck loads. An overall assessment of the economic and structural impact of using composites as an alternative to steel will be presented for riser systems and riser system components of both deepwater development concepts.

A New Periodic Cellular Metal With Kagome Trusses and Its Performance

Aerospace ◽  
2006 ◽  
Author(s):  
Yong-Hyun Lee ◽  
Ji-Eun Choi ◽  
Ki-Ju Kang
Keyword(s):  
Raw Materials ◽  
Future Market ◽  
New Materials ◽  
Specific Strength ◽  
Cellular Metal ◽  
High Specific Strength ◽  
New Type ◽  
Strength And Stiffness ◽  
Metal Wires ◽  
Very High

Periodic cellular metals (PCM), especially truss PCM's seem promising as new materials in 21 century. Various works have been performed for the mechanical and thermal performance. However, only a number of papers have been published regarding fabrication techniques of PCM, even though the techniques should determine whether PCM's is survived in the future market, or not. In this work a new type of PCM with Kagome trusses is presented. Continuous metal wires as the raw materials are assembled in six directions with least deflection, which gives very high specific strength and stiffness. The mechanical behavior under compression and bending of hand-made specimens is presented. Also, the benefits and features are discussed.

scholarly journals Methodologies for the optimal design of fibre-reinforced composite structures

2003 ◽  
Author(s):  
◽  
Ryan Elliot Smith
Keyword(s):  
Composite Structures ◽  
Specific Strength ◽  
Advantages And Disadvantages ◽  
Reinforced Composite ◽  
High Specific Strength ◽  
Reinforced Plastic ◽  
Stiffness Properties ◽  
Engineering Materials ◽  
Strength And Stiffness ◽  
Marine Engineering

Composites have become important engineering materials, especially in the fields of automotive, aerospace and marine engineering. This is due to the high specific strength and stiffness properties they offer. At present, fibre-reinforced plastic (FRP) laminates are some of the most common types of composite used. They are produced in various forms with different structural properties. As with all engineering materials, there is the existence of both advantages and disadvantages. One of the main disadvantages is the expense involved in producing both the material and the finished product. The design time is also costly as the material has to be designed concurrently with the structure.

Influence of Misch Metal Addition and Deformation Processes on Microstructure and Mechanical Properties in AZ61 Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 1707-1712 ◽  
Author(s):  
Suk Bong Kang ◽  
Hyoung Wook Kim ◽  
Sang Su Jeong ◽  
Jae Woon Kim
Keyword(s):  
Magnesium Alloys ◽  
Metallic Materials ◽  
Specific Strength ◽  
High Specific Strength ◽  
Misch Metal ◽  
Deformation Processes ◽  
Structural Parts ◽  
Strength And Stiffness ◽  
Metal Addition ◽  
Hexagonal Closed Packed

Magnesium alloys have been known as the best lightweight metallic materials for various applications of electronic equipments and automobile parts due to high specific strength and stiffness. The needs for wrought magnesium alloys have been increased for the application to structural parts in the form of sheets and bars. However, magnesium has a hexagonal closed-packed (HCP) crystal structure with a limited number of operative slip systems at room temperature, and its formability is restricted to mild deformation. The improvement of the formability of magnesium sheets for real applications is important. In order to increase formability of magnesium sheets at elevated temperature, one promising way is a grain refinement.

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