scholarly journals An Equivalent Homogenization Theoretical Method for Composite Sandwich Cylinders Subjected to Pure Bending

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2225
Author(s):  
Yang Liu ◽  
Fuwei Gu ◽  
Mingxuan Li ◽  
Xiaofeng Lu ◽  
Xiaolei Zhu
Keyword(s):  
Bending Strength ◽  
Strength Criterion ◽  
Theoretical Method ◽  
Homogenization Method ◽  
Bending Stiffness ◽  
Parameter Method ◽  
Skin Thickness ◽  
Pure Bending ◽  
Orthotropic Layer ◽  
Composite Sandwich

An equivalent theoretical homogenization method was proposed for composite sandwich cylinders subjected to pure bending. Firstly, based on a homogeneous orthotropic layer hypothesis, the trapezoidal corrugated sandwich core was found to be equivalent in a homogenization orthotropic layer with the nine equivalent mechanical properties. Then, Lekhnitskii’s theory, based on a unified connection parameter method, was introduced and applied in the equivalent composite sandwich cylinder. The method developed by Lekhnitskii is suitable for arbitrary combinations of winding layers with different winding angles and materials. Additionally, the bending stiffness of the equivalent sandwich cylinder could be calculated. By developing user subroutine of UMAT, the numerical calculation results were in a good agreement with the results of the proposed method. Further, according to the Hill–Tsai strength criterion and the maximum strain criterion, parametric study was done for specified bending stiffness and specified bending strength. The results show that the influence of core parameters on the specified bending stiffness and strength are lower than that of the skin parameters. Additionally, larger skin thickness and smaller winding angles could improve the specified bending stiffness and specified bending strength of the composite corrugated sandwich cylinders.

The Dynamic Characteristics of Rigid Frame Single-Rib Arch Bridge

2013 ◽  
Vol 368-370 ◽  
pp. 1426-1430
Author(s):  
Li Xiong Gu ◽  
Rong Hui Wang
Keyword(s):  
Dynamic Characteristics ◽  
Bending Strength ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Lateral Stiffness ◽  
Arch Bridge ◽  
Vertical Stiffness ◽  
Rigid Frame

In this paper, by establishing the finite element model to study the dynamic characteristics of rigid frame single-rib arch bridge. By respectively changing structural parameters of the span ratios, and the compressive stiffness of arch, and the bending stiffness of arch, and the bending stiffness of bridge girder, and the layout of boom to find out the regularity of the structure on lateral stiffness, and vertical stiffness, and torsional stiffness as well as dynamic properties, it come out the results of that lateral stiffness of the structure is weaker, and increasing the span ratios and the compressive strength of arch are conducive to the improvement of the overall stiffness, and improving the bending strength of arch and layout of boom are less effect on the overall stiffness and mode shape.

Composite Sandwich with Aluminum Foam Core and Adhesive Bonded Carbon Fiber Reinforced Thermoplastic Cover Layer

2017 ◽  
Vol 744 ◽  
pp. 277-281 ◽  
Author(s):  
Alexander Hackert ◽  
Claudia Drebenstedt ◽  
Tristan Timmel ◽  
Tomasz Osiecki ◽  
Lothar Kroll
Keyword(s):  
Mechanical Properties ◽  
Aluminum Foam ◽  
New Technologies ◽  
Bending Stiffness ◽  
Metal Composite ◽  
Fiber Reinforced ◽  
Metal Composites ◽  
Reinforced Plastics ◽  
Composite Sandwich ◽  
Fiber Reinforced Plastics

The combination of metals and fiber reinforced plastics is also known as hybrid metal composites. They offer the fusion of the good static mechanical properties of the fiber reinforced plastics and the good dynamic mechanical properties of the metal. For that reason, parts made of hybrid metal composites are predestined for the use as load relevant parts. The purpose of this study was to develop new technologies for semi finished hybrid metal composite materials. Thermoplastic Fiber-Reinforced Composites (TP-FRC) were arranged with new, isotropic, closed pore Aluminum Foam (AF) structures to an Extrinsically Combined Composite Sandwich (ECCS) by adhesive bonding. They form the basis for novel weight-optimized as well as cost-effective applications. The entire manufacturing process for the continuous semi-finished product was examined and verified according DIN EN 2563. This was done with regard to subsequent characterization by the specific bending modulus and specific bending stiffness. The examinations show a high bending stiffness and high strength structures combined with excellent damping properties at high damage tolerances. These are the most requested in automotive applications.

scholarly journals Experimental Study on Sandwich Bridge Decks with GFRP Face Sheets and a Foam-Web Core Loaded under Two-Way Bending

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Ruili Huo ◽  
Weiqing Liu ◽  
Li Wan ◽  
Yuan Fang ◽  
Lu Wang
Keyword(s):  
Experimental Study ◽  
Energy Dissipation ◽  
Bending Strength ◽  
Bridge Decks ◽  
Sheet Thickness ◽  
Highway Bridges ◽  
Bending Stiffness ◽  
Face Sheet ◽  
Displacement Ductility ◽  
Ultimate Bending Strength

In recent years, the sandwich bridge decks with GFRP face sheets and light weight material core have been widely used in the world due to their advantages of low cost, high strength to weight ratios, and corrosion resisting. However, as the bridge decks, most of them are used in foot bridges rather than highway bridges because the ultimate bending strength and initial bending stiffness are relatively low. To address this issue and expand the scope of use, a simple and innovative sandwich bridge deck with GFRP face sheets and a foam-web core, manufactured by vacuum assisted resin infusion process, is developed. An experimental study was carried out to validate the effectiveness of this panel for increasing the ultimate bending strength and initial bending stiffness under two-way bending. The effects of face sheet thickness, foam density, web thickness, and web spacing on displacement ductility and energy dissipation were also investigated. Test results showed that, compared to the normal foam-core sandwich decks, an average approximately 657.1% increase in the ultimate bending strength can be achieved. Furthermore, the bending stiffness, displacement ductility, and energy dissipation can be enhanced by increasing web thickness, web height, and face sheet thickness or decreasing web spacing.

On the Mechanics of Grey Cast Iron Under Pure Bending

1986 ◽  
Vol 108 (2) ◽  
pp. 141-146 ◽  
Author(s):  
G. S. A. Shawki ◽  
S. A. R. Naga
Keyword(s):  
Cast Iron ◽  
Bending Strength ◽  
Neutral Axis ◽  
Grey Cast Iron ◽  
Stress And Strain ◽  
Pure Bending ◽  
Rectangular Section ◽  
Bending Strain ◽  
Grey Cast ◽  
Lamellar Graphite

This paper presents the results of experiments conducted on lamellar graphite grey cast iron of rectangular section subjected to pure bending. Strain measurements confirm the traditional speculation that plane sections remain plane under strain. Owing to the nonlinear relationship between stress and strain, however, the neutral axis of a loaded specimen is shown to shift away from the centroidal axis. This shift is evidently amplified with increased loading. A computer program is herein specially devised for calculating the shift in neutral axis through satisfaction of the conditions of equilibrium together with checking for possible crack initiation at the extension side. While the simple flexural formula holds very nearly true for the compression side, it fails, however, to predict stresses on the extension side, the situation being further aggravated by higher bending moments. The apparent high bending strength of grey cast iron is fully accounted for.

Thickness Effect of Polyurethane Foam Core on the Flexural Behaviour of Composite Sandwich Materials

2015 ◽  
Vol 758 ◽  
pp. 1-6
Author(s):  
Pramaditya Ardiyanto ◽  
Putu Suwarta ◽  
Sutikno ◽  
Indra Sidharta ◽  
Wahyu Wijanarko
Keyword(s):  
Failure Mechanism ◽  
Polyurethane Foam ◽  
Bending Strength ◽  
Thickness Effect ◽  
Positive Trend ◽  
Foam Core ◽  
High Modulus ◽  
Composite Sandwich ◽  
Material Stiffness ◽  
Core Thickness

This study explored the feasibility of flexural performance of composite sandwich material composed of various low density polyurethane foam core thickness sandwiched between GFRP skins. The mechanical behaviour of this material was assessed by carrying out a flexural testing. Each spesimen had a nominal dimensions of 110 mm x 30 mm x (c + 4 mm). These spesimens with various core thickness (c) of 2 mm. 5 mm. and 8 mm were then tested in three point bending according to ASTM C 393-00. This study revealed that. by incorporating the thickest core ( 8 mm ) . the bending strength decreases by 42.3 % compared to 5 mm core and it further decreases by 72.6 % compared to 2 mm core. The material stiffness showed positive trend for the thickest core (8 mm). it increases by 53.1 % and 78.1 % compared to 5 mm core and 2 mm core respectively. Low shear modulus of polyurethane foam core contributed to the low bending strength of composite sandwich material with 8 mm core. This was further confirmed by failure analysis under optical microscope which revealed that core shear failure was the dominant failure mechanism for 8 mm core. Meanwhile the dominant failure mechanism for 2 mm core and 5 mm core was microbuckling which confirm the high modulus of GFRP skin. The material stiffness was affected by the high modulus of GFRP skin and the core thickness.

scholarly journals Static and thermal behaviour of ship structure sandwich panels

2019 ◽  
pp. 463-463
Author(s):  
Nicușor Baroiu ◽  
Elena Beznea ◽  
Gelu Coman ◽  
Ionel Chirică
Keyword(s):  
Composite Laminates ◽  
Thermal Loading ◽  
Bending Strength ◽  
Sandwich Panels ◽  
Bending Test ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Ship Structure ◽  
Composite Sandwich ◽  
Glass Fiber Reinforced

The mechanical properties of certain flexible core materials of ship structure sandwich panels, having skins made of metallic or composite laminates may be significantly influenced by the temperature variations that may occur during the operational loading. At the same time, the improving knowledge of the behaviour of these panels in terms of bending strength and other stress / strain related aspects in various harsh conditions increases their superiority in terms of weight-to-strength ratio, high stiffness, easy to manufacture, acoustic and thermal insulation. In the paper, the behaviour of the ship structural rectangular sandwich panels to the mechanical and thermal loading are presented. The sandwiches have a special core of 20 mm and skins made out of different materials (glass fiber reinforced polyester, steel and aluminium) with a thickness of 3 mm. Analysis consists of the behaviour of the composite sandwich panels in the bending test at constant speed by the three-point method, for three distances between different supports, by measuring the maximum displacement and force applied to the specimens under various thermal fields. The sandwich structures are also thermally analysed, determining their thermal conductivity by the heat flow measurement method. The experimental results are compared with the results obtained by finite element analysis in numerical simulation of all modelling cases.

scholarly journals An Innovative Elastoplastic Analysis for Soft Surrounding Rock considering Supporting Opportunity Based on Drucker-Prager Strength Criterion

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Rui Wang ◽  
Xu-dong Liu ◽  
Jian-biao Bai ◽  
Shuai Yan ◽  
Jun Xu
Keyword(s):  
Strength Criterion ◽  
Homogenization Method ◽  
Surrounding Rock ◽  
Theoretical Research ◽  
Underground Engineering ◽  
Support Design ◽  
Interval Distance ◽  
Space Effect ◽  
The Stability ◽  
Supporting Condition

In order to study the mechanism of excavation and supporting process of equivalent circular roadway, the model of soft roadway was established firstly. The elastoplastic solutions in excavation process were deduced based on Drucker-Prager strength criterion. Then, the elastoplastic solution under supporting condition was obtained based on homogenization method under the condition of rockbolts and liner supporting. Lastly, an example was analyzed to study the effect of different factors such as “space effect,” supporting opportunity, stresses, surrounding displacement, and the radius of plastic zone. Based on theoretical research case, the change rules of considering the “space effect” and the supporting opportunity when calculating the subarea of the roadway were discussed, the control of interval distance of rockbolts on the displacement of surrounding rock mainly reflecting in the plastic residual zone and the “space effect” in excavation, and the supporting time to control the displacement of surrounding rock not being ignored are revealed. The results can provide an important theoretical basis for the stability evaluation and quantitative support design of roadway surrounding rock. Therefore, the “space effect” and the supporting time to control the displacement and stresses of surrounding rock can not being ignored in underground engineering.

Selected properties of particleboard made of raspberry Rubus idaeus L. lignocellulosic particles

2019 ◽  
Vol 105 ◽  
pp. 113-124
Author(s):  
ANITA WRONKA ◽  
GRZEGORZ KOWALUK
Keyword(s):  
Physical Properties ◽  
Bending Strength ◽  
Fractional Composition ◽  
Strength Criterion ◽  
Rubus Idaeus ◽  
Raw Material ◽  
Laboratory Conditions ◽  
Mechanical And Physical Properties ◽  
European Standards

Selected properties of particleboard made of raspberry Rubus idaeus L. lignocellulosic particles. The aim of the research was to confirm the possibility of using lignocellulosic particles of raspberry Rubus idaeus L. stalks as an alternative raw material in particleboard technology. Within the scope of work, it was to produce particleboards from raspberry lignocellulosic particles in laboratory conditions, and to investigate selected mechanical and physical properties of the produced boards. In addition to the aforementioned tests, the characterization of the lignocellulosic raw material used in the tests (density, bark share, fractional composition) was carried out. The tests have shown that it is possible to produce the furniture particleboards with use the lignocellulosic particles of raspberry Rubus idaeus L. To meet the requirements of the European standards for furniture panels, such particleboards must contain less than 50% of raspberry particles with density 650 kg/m3 (due to the bending strength criterion).

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