scholarly journals Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Hai Fang ◽  
Huiyuan Shi ◽  
Yue Wang ◽  
Yujun Qi ◽  
Weiqing Liu
Keyword(s):  
Fem Simulation ◽  
Sandwich Panels ◽  
Transformation Method ◽  
Steel Plates ◽  
Bending Test ◽  
Composite Sandwich ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Ultimate Failure

This study presented a new form of composite sandwich panels, with steel plates as facesheets and bonded glass fiber-reinforced polymer (GFRP) pultruded hollow square tubes as core. In this novel panel, GFRP and steel were optimally combined to obtain high bending stiffness, strength, and good ductility. Four-point bending test was implemented to analyze the distribution of the stress, strain, mid-span deflection, and the ultimate failure mode. A section transformation method was used to evaluate the stress and the mid-span deflection of the sandwich panels. The theoretical values, experimental results, and FEM simulation values are compared and appeared to be in good agreement. The influence of thickness of steel facesheet on mid-span deflection and stress was simulated. The results showed that the mid-span deflection and stress decreased and the decent speed was getting smaller as the thickness of steel facesheet increases. A most effective thickness of steel facesheet was advised.

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.

Experimental Testing of Fiber Reinforced Polymer-Concrete Composite Beam

2010 ◽  
Vol 168-170 ◽  
pp. 549-552
Author(s):  
Yan Lei Wang ◽  
Qing Duo Hao ◽  
Jin Ping Ou
Keyword(s):  
Composite Beam ◽  
Experimental Testing ◽  
Coarse Sand ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Polymer Concrete ◽  
Fiber Reinforced ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Box Beam

A new form of fiber reinforced polymer (FRP)-concrete composite beam is proposed in this study. The proposed composite beam consists of a GFRP box beam combined with a thin layer of concrete in the compression zone. The interaction between the GFRP beam and the concrete was obtained by bonding coarse-sand on the top flange of the GFRP beam. One GFRP box beam and one GFRP-concrete composite beam were investigated in four-point bending test. Load-deflection response, mid-span longitudinal strain distributions and interface slip between GFRP beam and the concrete for the proposed composite beam were studied. Following conclusions are drawn from this study: (1) the stiffness and strength of the composite beam has been significantly increased, and the cost-to-stiffness ratio of the composite beam has been drastically reduced comparing with GFRP-only box beam; (2) a good composite action has been achieved between the GFRP beam and the concrete; (3) crushing of concrete in compression defines flexural collapse of the proposed composite beam..

scholarly journals Experimental Study on Bending Performance of Composite Sandwich Panel with New Mixed Core

2019 ◽  
Vol 275 ◽  
pp. 02018
Author(s):  
Jing Zhang ◽  
Xiamin Hu ◽  
Wan Hong ◽  
Bing Zhang ◽  
Chengli Zhang
Keyword(s):  
Experimental Investigation ◽  
Polyurethane Foam ◽  
Failure Mode ◽  
Shear Failure ◽  
Sandwich Panels ◽  
Tensile Failure ◽  
Bending Test ◽  
Bending Performance ◽  
Composite Sandwich Panels ◽  
Composite Sandwich

This paper presents an experimental investigation of bending performance of composite sandwich panels with new mixed core, sandwich panels were tested by four-point bending test. Parametric study was conducted to investigate the influence of different core materials on the failure mode, ultimate bearing capacity, stiffness and ductility of composite sandwich panels. The results of the experimental investigation showed that the mixed core can change the failure mode of sandwich panels. The failure mode of wooden panels is characterized by tensile failure of bottom wood, and the failure mode of composite sandwich panels with wood core is that the surface layer and core are stripped and the webs are damaged by shear, while the failure mode of composite sandwich panels with wood and polyurethane foam mixed core is the shear failure of the web. Composite sandwich panels with GFRP-wood-polyurethane foam core have better bending performance and can effectively reduce the weight of panels.

scholarly journals Strengthening Reinforced Concrete Beams with CFRP and GFRP

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Mehmet Mustafa Önal
Keyword(s):  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Strength Increase ◽  
Fiber Reinforced ◽  
Flexural Stress ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Reinforced Beams

Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP) or glass fiber reinforced polymer (GFRP). The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150×250×2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the open air for 21 days. Four-point bending tests were made on the beam test specimens and the data were collected. Data were evaluated in terms of load displacement, bearing strength, ductility, and energy consumption. In the CFRP and GFRP reinforced beams, compared to controls, 38% and 42%, respectively, strength increase was observed. In all beams, failure-flexural stress occurred in the center as expected. Most cracking was observed in the flexural region 4. A comparison of CFRP and GFRP materials reveals that GFRP enforced parts absorb more energy. Both materials yielded successful results. Thicker epoxy application in both CFRP and GFRP beams was considered to be effective in preventing break-ups.

scholarly journals Screw head plugs increase the fatigue strength of stainless steel, but not of titanium, locking plates

2018 ◽  
Vol 7 (12) ◽  
pp. 629-635 ◽  
Author(s):  
L-W. Hung ◽  
C-K. Chao ◽  
J-R. Huang ◽  
J. Lin
Keyword(s):  
Stainless Steel ◽  
Fatigue Strength ◽  
Steel Plates ◽  
Bending Test ◽  
Type I ◽  
Locking Plates ◽  
Type Ii ◽  
Screw Head ◽  
Type Iii ◽  
Four Point Bending

ObjectivesScrew plugs have been reported to increase the fatigue strength of stainless steel locking plates. The objective of this study was to examine and compare this effect between stainless steel and titanium locking plates.MethodsCustom-designed locking plates with identical structures were fabricated from stainless steel and a titanium alloy. Three types of plates were compared: type I unplugged plates; type II plugged plates with a 4 Nm torque; and type III plugged plates with a 12 Nm torque. The stiffness, yield strength, and fatigue strength of the plates were investigated through a four-point bending test. Failure analyses were performed subsequently.ResultsFor stainless steel, type II and type III plates had significantly higher fatigue strength than type I plates. For titanium, there were no significant differences between the fatigue strengths of the three types of plates. Failure analyses showed local plastic deformations at the threads of screw plugs in type II and type III stainless steel plates but not in titanium plates.ConclusionThe screw plugs could increase the fatigue strength of stainless steel plates but not of titanium plates. Therefore, leaving screw holes open around fracture sites is recommended in titanium plates. Cite this article: L-W. Hung, C-K. Chao, J-R. Huang, J. Lin. Screw head plugs increase the fatigue strength of stainless steel, but not of titanium, locking plates. Bone Joint Res 2018;7:629–635. DOI: 10.1302/2046-3758.712.BJR-2018-0083.R1.

Flexural performance of composite grid panels with deep ribs

2020 ◽  
Vol 39 (11-12) ◽  
pp. 443-458
Author(s):  
Jiye Chen ◽  
Hai Fang ◽  
Feng Gao ◽  
Weiqing Liu
Keyword(s):  
Glass Fiber ◽  
Bending Stiffness ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Flexural Performance ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Composite Grid

This paper reports on the flexural performance of an innovative composite grid panel composed of glass fiber-reinforced polymer face skins and deep glass fiber-reinforced polymer ribs with a trapezoidal cross-section. Three-point and four-point bending experiments were performed to demonstrate the feasibility of the composite grid panels under concentrated loads. Compared with the composite grid panels without skins, maximum increases in the ultimate load, and initial bending stiffness of the composite grid panels of approximately 68.2% and 306.7%, respectively, were achieved with the existence of both upper and lower skins. Furthermore, an analytical analysis was carried out to predict the initial bending stiffness and mid-span deflection of the composite grid panels. A comparison of the analytical and experimental results showed that the analytical model accurately predicted the flexural performance of the composite grid panels subjected to three-point and four-point bending. Failure mechanism maps were constructed to predict the mechanical response and failure modes of the composite grid panels. Moreover, the validated model was used in a parametric analytical study to further estimate the effects of various parameters on the flexural performance of the composite grid panels. The results demonstrated that the initial bending stiffness can be significantly improved by increasing the trapezoidal section ratio, face skin thickness, and grid height.

scholarly journals Flexural Performance of a Hybrid Bridge Deck with Pultruded Fibre Reinforced Polymer Composite Sandwich Panels

2018 ◽  
Vol 13 (3) ◽  
pp. 165-191 ◽  
Author(s):  
Lei Wu ◽  
Yujun Qi ◽  
Weiqing Liu
Keyword(s):  
Working Conditions ◽  
Bridge Deck ◽  
Composite Sandwich ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Hybrid Bridge ◽  
Service Load ◽  
Fibre Reinforced Polymer ◽  
Wheel Loading ◽  
Eccentric Wheel

Hybrid bridge decks with the pultruded fibre reinforced polymer have advantageous properties but easily crack because of their unsatisfactory transverse strength and shear strength. This study proposed a type of bridge deck composed of innovative pultruded fibre reinforced polymer composite sandwich panels. Using four-point bending tests, concentric wheelloading tests and eccentric wheel-loading tests combined with first-order shear deformation theory, this study investigated the failure mode, flexural capacity, deformation and ductility of hybrid bridge decks under different working conditions. Under four-point bending and concentric wheel loading, the primary failure modes for this hybrid bridge deck were shear failures along the fibre direction and buckling failure of the upper panel. Under eccentric wheel loading, the primary failure mode was a torsional failure due to the eccentric load. The bearing capacities of the hybrid bridge deck under the three working conditions were 3.8, 3.5 and 3.2 times the service load of a Class I vehicle load, respectively. Besides, the hybrid bridge deck remained in the linear elastic stress state at 2.6 times the service load, indicating that this hybrid bridge deck withstands relatively large vehicle overload without visible damage. The ductility values of this hybrid bridge deck under the three working conditions were 1.79, 2.09 and 2.00, respectively, which are higher than the values for an ordinary pultruded bridge deck. Therefore, the proposed design has the relatively good energy-dissipating capacity, which improves the emergency capacity of the bridge deck.

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