scholarly journals Experimental and modeling investigations of the behaviors of syntactic foam sandwich panels with lattice webs under crushing loads

2021 ◽  
Vol 60 (1) ◽  
pp. 450-465
Author(s):  
Zhilin Chen ◽  
Yu Zhang ◽  
Jun Wang ◽  
Hota GangaRao ◽  
Ruifeng Liang ◽  
...  

Abstract The composite sandwich structures with foam core and fiber-reinforced polymer skin are prone to damage under local impact. The mechanical behavior of sandwich panels (glass fiber-reinforced polymer [GFRP] skin reinforced with lattice webs and syntactic foams core) is studied under crushing load. The crushing behavior, failure modes, and energy absorption are correlated with the number of GFRP layers in facesheets and webs, fiber volume fractions of facesheets in both longitudinal and transverse directions, and density and thickness of syntactic foam. The test results revealed that increasing the number of FRP layers of lattice webs was an effective way to enhance the energy absorption of sandwich panels without remarkable increase in the peak load. Moreover, a three-dimensional finite-element (FE) model was developed to simulate the mechanical behavior of the syntactic foam sandwich panels, and the numerical results were compared with the experimental results. Then, the verified FE model was applied to conduct extensive parametric studies. Finally, based on experimental and numerical results, the optimal design of syntactic foam sandwich structures as energy absorption members was obtained. This study provides theoretical basis and design reference of a novel syntactic foam sandwich structure for applications in bridge decks, ship decks, carriages, airframes, wall panels, anticollision guard rails and bumpers, and railway sleepers.

2020 ◽  
Vol 01 (04) ◽  
pp. 111-115
Author(s):  
Md. Rakibul Islam ◽  
Md Arifuzzaman ◽  
Asif Karim Neon ◽  
Md. Shahe Duzzaman ◽  
Md. Rafiul Islam

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.


Author(s):  
A. A. Mutalib ◽  
Norhisham Bakhary

Kajian terhadap keupayaan struktur dalam menahan beban letupan menggunakan Fiber Reinforced Polymer (FRP) adalah sangat terhad. Dalam kajian ini, satu analisis terhadap keupayaan FRP bagi menahan beban letupan dilakukan. Tujuan analisis ini adalah untuk memperolehi hubungan antara kekuatan FRP, bilangan lapisan ketebalan FRP dan susunatur FRP bagi menahan kekuatan sesuatu beban letupan. Kajian ini dilakukan mengunakan model tiang diperkukuh dengan FRP yang dibina menggunakan perisian LS–DYNA. Ia melibatkan beberapa siri simulasi untuk meramalkan tindakbalas letupan dan kerosakkan pada tiang sekiranya sesuatu beban letupan dikenakan. Melalui simulasi ini, kekuatan FRP, bilangan lapisan ketebalan FRP dan susunatur FRP dapat ditentukan. melalui keputusan–keputusan yang diperolehi, pressure–impulse diagram (P–I) bagi tiang yang diperkukuhkan dengan FRP dapat dibentuk. Kata kunci: Pengukuhan; beban letupan; FRP; P–I diagrams There are only limited studies that directly correlate the increase in structural capacities in resisting the blast loads with the fiber reinforced polymer (FRP) strengthenin. In this paper, numerical analyses of dynamic response and damage of reinforced concrete (RC) columns strengthened with FRP to blast loads are carried out using the commercial software LS–DYNA. A series of simulations are performed to predict the blast response and damage of columns with different FRP type. The simulations also involved parametric studies by varying the FRP thickness, configuration, different column dimension, concrete strength, and longitudinal and transverse reinforcement ratio. The numerical results are used to develop pressure–impulse (P–I) diagrams of FRP strengthened RC columns. Based on the numerical results, the empirical formulae are derived to calculate the pressure and impulse asymptotes of the P–I diagrams of RC columns strengthened with FRP. Key words: Strengthening; blast loads; FRP; P–I diagrams


Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2532
Author(s):  
Rahima Shabeen Sirajudeen ◽  
Rajesh Sekar

Glass fiber reinforced polymers (GFRP), with their advantage of corrosion resistance, have potential to be used as structural members in civil engineering constructions. Pultruded GFRP angle section trusses could be used instead of steel sections in remote areas and in areas prone to corrosion. The objective of this paper is to study the strength of GFRP angle sections under concentric axial load. Glass fiber reinforced polymer (GFRP) made of E-glass and Isophthalic polyester resin and manufactured by pultrusion process was used for the experimental study. Two GFRP angle sections of size 50 × 50 × 6 mm and 50 × 50 × 4 mm and lengths 500 mm, 750 mm, and 1000 mm were chosen for the study. Further, finite experimental element analysis of the GFRP angle sections was done using ANSYS software and validated with the experimental results. The validated FE model was used for parametric studies varying the slenderness ratio and flange width to thickness ratio (b/t) ratio. It was observed that length of the specimen and thickness influenced the buckling load and buckling mode. An increase in b/t ratio from 8.3 to 12.5 decreases the load carrying capacity by almost 60% at a slenderness ratio of 50.


Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 222
Author(s):  
Liangliang Wei ◽  
Ji-Hua Zhu ◽  
Zhijun Dong ◽  
Jun Liu ◽  
Wei Liu ◽  
...  

Carbon fiber reinforced polymer (CFRP) has been used as a dual-functional material in a hybrid intervention system (ICCP-SS) which integrates the impressed current cathodic protection (ICCP) and structural strengthening (SS). The mechanical behavior of CFRP as an anode has been investigated in some solution environments. However, the anodic and mechanical behavior of CFRP bonded to concrete is unclear. This paper focuses on the anodic and mechanical performance of CFRP bonded to the chloride-contaminated concrete by conducting an electrochemical (EC) test. The method of bonding the CFRP to the concrete and the shape of the steel embedded in the concrete were considered. The current densities of 20 mA/m2 and 100 mA/m2 were applied during 120-day and 310-day EC tests. The electrode potentials and driving voltages were recorded, and the bond interfaces of the CFRP were inspected after EC test. The residual tensile strength and failure modes of the CFRP were analyzed after tensile tests. Finally, the long-term performance of CFRP as a dual-functional material in ICCP-SS system was discussed. Results show that the externally bonding CFRP in ICCP-SS system can not only protect the steel in chloride-contaminated concrete effectively but also maintain 70% of the original tensile strength of CFRP at a charge density of 744 A·h/m2. The expected service period of CFRP as a dual-functional material bonded to the chloride-contaminated concrete was determined to be more than 42.5 years.


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