scholarly journals Characteristics of CFRP/PU foam and GFRP/PU sandwich beams having initial debond between facesheet and core

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Gurpinder Singh Dhaliwal
Keyword(s):  
Polyurethane Foam ◽  
Sandwich Beam ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Face Sheet ◽  
Sandwich Beams ◽  
Fiber Reinforced ◽  
The Core ◽  
Reinforced Polymer ◽  
Pu Foam

AbstractIn the present investigation, we present, the flexural characteristics of carbon fiber reinforced polymer/polyurethane foam and glass fiber reinforced polymer/polyurethane foam sandwich beams having partial debonding between facesheet and core that acts interfacial degradation and hinders the load transfer between facesheets and core. An initial pre-crack between core and face sheet is created by placing a Teflon sheet at the interface on one end of the beams during the manufacturing of sandwich beams. A comparative analysis is carried out to study the effect of using CFRP and Eglass prepregs as face sheet material on such sandwich beams. The flexural behavior of GFRP/PU sandwich beams having initial debond is characterized and analyzed under both three- and four-point loadings. Lastly, the effect of varying the support span length on the flexural response of CFRP/PU sandwich beam having initial debond is also investigated. It was found that the degraded sandwich beams having woven CFRP facesheets have slightly higher stiffness and peak load level as compared to the sandwich beam having cross ply GFRP facesheets. GFRP/PU foam sandwich beam showed higher ductile behavior prior to progressive failure of the sandwich beam. It was observed that the crack tip of the implanted interfacial debond acts as a medium to trigger the interfacial damage followed by the shear failure of the core due to the progression of the initial crack into the core.

Experimental and analytical behaviour of sandwich composites with glass fiber-reinforced polymer facings and layered fiber mat cores

2020 ◽  
Vol 54 (30) ◽  
pp. 4875-4887
Author(s):  
Lauren MacDonnell ◽  
Pedram Sadeghian
Keyword(s):  
Glass Fiber ◽  
Analytical Model ◽  
Sandwich Beam ◽  
Fiber Reinforced Polymer ◽  
Sandwich Beams ◽  
Sandwich Composites ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

This paper presents the results of experimental and analytical studies on the behaviour of sandwich beams fabricated with layered cores and glass fiber-reinforced polymer (GFRP) composite facings. The GFRP facings were fabricated using a unidirectional fiberglass fabric and epoxy resin, and the cores were fabricated using a thin non-woven continuous-strand polyester fiber mat with a thickness of 4.1 mm. A total of 30 sandwich beams with the width of 50 mm were prepared tested with five varying core configurations including cores made with one, two, or three layers of the fiber mat core and with or without the inclusion of intermediate GFRP layers. The specimens were tested up to failure under four-point bending at two different spans to characterize flexural and shear properties of the specimens. Two types of failure were observed, namely crushing of the compression facesheet and core shear. The load-deflection, load-strain, and moment-curvature behaviour were analyzed and using the results the flexural stiffness, shear stiffness, and core shear modulus were calculated. An analytical model was also developed to predict load-deflection behaviour and failure loading of sandwich specimens with varying core layouts. After verification, the analytical model was used for a parametric study of cases not considered in the experimental study, including additional GFRP and fiber mat core layers. It was shown that additional fiber mat core layers and the inclusion of intermediate GFRP layers can increase the strength and overall stiffness of a sandwich beam, while additional GFRP layers can only increase the overall stiffness of the system. The analytical model can be used to optimize the configuration of layered sandwich composites for cost effective rehabilitation techniques of culverts, pipelines, and other curved-shape structures where a thin, flexible core is needed to accommodate the curvature of the existing structure.

scholarly journals Flexural Behavior of Sandwich Composite Made of JFRP Honeycomb as Core and GFRP as Skin

2020 ◽  
Vol 01 (04) ◽  
pp. 111-115
Author(s):  
Md. Rakibul Islam ◽  
Md Arifuzzaman ◽  
Asif Karim Neon ◽  
Md. Shahe Duzzaman ◽  
Md. Rafiul Islam
Keyword(s):  
Energy Absorption ◽  
Polymer Composite ◽  
Sandwich Structures ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Face Sheet ◽  
Sandwich Composite ◽  
Fiber Reinforced ◽  
Steel Mold ◽  
Reinforced Polymer

The increasing demand of lightweight, strong and sustainable materials in aerospace, automobile and marine sectors is leading towards the development of new materials and structures. The sandwich composite is one of them which is well-known for their high strength to weight ratio and the fiber based sandwich structures with cellular core show comparatively good mechanical, acoustic, thermal and energy absorption properties than metallic cellular structure. The purpose of this work is to fabricate a sandwich structure with jute fiber reinforced polymer composite (JFRP) as core and glass fiber reinforced polymer composite (GFRP) as face sheet and to investigate bending properties of the fabricated structures for varying face sheet thicknesses. Skin and core honeycomb strips of the sandwich composites were manufactured using hand layup method and steel mold was used to obtain honeycomb shape. Flexural test results show that face sheet thickness has significant effect on the flexural behavior such as peak load, flexural strength and energy absorption. The failure mechanism during bending tests were also identified which would serve as a basis for future improvement of manufactured composites. The delamination at the interface between the core and the face sheet was the first catastrophic failure during bending. The presented sandwich structures are able to carry a significant amount of load even after failure.

Flexural behavior of fire damaged self-compacting concrete beams strengthened with fiber reinforced polymer (FRP) wrapping

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mervin Ealiyas Mathews ◽  
Anand N ◽  
Diana Andrushia A ◽  
Tattukolla Kiran ◽  
Khalifa Al-Jabri
Keyword(s):  
Elevated Temperature ◽  
Carbon Fiber ◽  
Ultimate Load ◽  
Research Work ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Fiber Reinforced ◽  
Self Compacting Concrete ◽  
Content Type ◽  
Reinforced Polymer

PurposeBuilding elements that are damaged by fire are often strengthened by fiber wrapping techniques. Self-compacting concrete (SCC) is an advanced building material that is widely used in construction due to its ability to flow and pass through congested reinforcement and fill the required areas easily without compaction. The aim of the research work is to examine the flexural behavior of SCC subjected to elevated temperature. This research work examines the effect of natural air cooling (AC) and water cooling (WC) on flexural behavior of M20, M30, M40 and M50 grade fire-affected retro-fitted SCC. The results of the investigation will enable the designers to choose the appropriate repair technique for improving the service life of structures.Design/methodology/approachIn this study, an attempt has been made to evaluate the flexural behavior of fire exposed reinforced SCC beams retrofitted with laminates of carbon fiber reinforced polymer (CFRP), basalt fiber reinforced polymer (BFRP) and glass fiber reinforced polymer (GFRP). Beam specimens were cast with M20, M30, M40 and M50 grades of SCC and heated to 925ºC using an electrical furnace for 60 min duration following ISO 834 standard fire curve. The heated SCC beams were cooled by either natural air or water spraying.FindingsThe reduction in the ultimate load carrying capacity of heated beams was about 42% and 55% for M50 grade specimens that were cooled by air and water, respectively, in comparison with the reference specimens. The increase in the ultimate load was 54%, 38% and 27% for the specimens retrofitted with CFRP, BFRP and GFRP, respectively, compared with the fire-affected specimens cooled by natural air. Water-cooled specimens had shown higher level of damage than the air-cooled specimens. The specimens wrapped with carbon fiber could able to improve the flexural strength than basalt and glass fiber wrapping.Originality/valueSCC, being a high performance concrete, is essential to evaluate the performance under fire conditions. This research work provides the flexural behavior and physical characteristics of SCC subjected to elevated temperature as per ISO rate of heating. In addition attempt has been made to enhance the flexural strength of fire-exposed SCC with wrapping using different fibers. The experimental data will enable the engineers to choose the appropriate material for retrofitting.

scholarly journals Conceptual Design of Composite Sandwich Structure Submarine Radome

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1966 ◽  
Author(s):  
Waqas ◽  
Shi ◽  
Imran ◽  
Khan ◽  
Tong ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Materials ◽  
Conceptual Design ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
The Core ◽  
Reinforced Polymer ◽  
Sandwich Core

Radomes are usually constructed from sandwich structures made of materials which usually have a low dielectric constant so that they do not interfere with electromagnetic waves. Performance of the antenna is increased by the appropriate assortment of materials enabling it to survive under marine applications, and it depends on composite strength-to-weight ratio, stiffness, and resistance to corrosion. The design of a sandwich core submarine radome greatly depends on the material system, number of layers, orientation angles, and thickness of the core material. In this paper, a conceptual design study for a sandwich core submarine radome is carried out with the help of finite element analysis (FEA) using two unidirectional composite materials—glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP)—as a skin material and six different core materials. Conceptual designs are obtained based on constraints on the composite materials’ failure, buckling, and strength. The thickness of the core is reduced under constraints on material and buckling strength. Finite element analysis software ANSYS WORKBENCH is used to carry out all the simulations.

Eddy Current Array Inspection of Damaged CFRP Sandwich Panels

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
P. R. Underhill ◽  
T. Rellinger ◽  
T. W. Krause ◽  
D. Wowk
Keyword(s):  
Carbon Fiber ◽  
Eddy Current ◽  
Sandwich Panels ◽  
Fiber Reinforced Polymer ◽  
Face Sheet ◽  
Carbon Fiber Reinforced Polymer ◽  
The Core ◽  
Reinforced Polymer ◽  
Different Types ◽  
Phase Map

Abstract The use of eddy current (EC) arrays to detect damage in sandwich panels, such as disbonding of the carbon fiber reinforced polymer (CFRP) face-sheet to the core, is investigated. It is shown that the array is very sensitive to slight core crush and can readily find small dents and disbonds. At the same time, the eddy current array can look much deeper into the honeycomb to detect defects such as tears. The phase map of the EC signal can be used in some cases to distinguish between different types of damage. EC arrays offer the ability to rapidly scan large areas of CFRP panels.

Flexural Behavior of Reinforced-Concrete (RC) Beams Strengthened with Hemp Fiber-Reinforced Polymer (FRP) Composites

2016 ◽  
Vol 860 ◽  
pp. 156-159
Author(s):  
Seyha Yinh ◽  
Qudeer Hussain ◽  
Winyu Rattanapitikon ◽  
Amorn Pimanmas
Keyword(s):  
Reinforced Concrete ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Hemp Fiber ◽  
Flexural Strengthening ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
Fiber Thickness

This experimental study has been conducted on the efficiency of epoxy-bonded hemp fiber reinforced polymer (FRP) composites in flexural strengthening of reinforced concrete (RC) beams. A total of five RC beams were cast and tested up to failure. The test parameters included fiber thickness and strengthening configuration. The experimental results show the capability of hemp FRP composites to increase the loading capacity in flexure of RC beams compared with the un-strengthened beam. The enhancement of ultimate load becomes more significant as the fiber thickness is increased. The effectiveness of strengthened beams in U-wrapped scheme is found greater than strengthened beams in bottom-only scheme. Based on results, it indicates that hemp FRP has a potential to considerably increase the strength and stiffness of the original RC beam.

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