Fiber Reinforced Polymer Composite Sandwich Research Articles

Development and evaluation of load-bearing fiber reinforced polymer composite panel systems with tongue and groove joints

This paper focuses on recent advances made in design, development, manufacturing, evaluation and modeling of load bearing fiber reinforced polymer (FRP) composite sandwich panel systems including tongue and groove joints. Several processes have been researched in collaboration with industry partners for production of composite panels, including: 1) pultrusion, 2) high temperature resin spread and infusion, 3) vacuum assisted resin transfer molding (VARTM), and 4) compression molding. The advantages and disadvantages of each process are discussed with emphasis on the high temperature resin infusion process. Composite laminates are characterized in terms of strength and stiffness under tension, bending, and shear in relation to longitudinal and transverse fiber orientations. Thermo-mechanical property variations of the FRP composite sandwich panels including joint responses are presented in terms of: 1) production processes, 2) carbon versus E-glass fiber, 3) vinyl ester versus epoxy, and 4) panel and joint design and efficiency including classical lamination theory. The sandwich panels are evaluated at component and full scales under static four point bending loads and further analyzed using classical finite element models for their mechanical responses.

Localized damage response of carbon fiber reinforced polymer composite sandwich panel after thermal exposure

An experimental study was conducted to investigate the effect of thermal exposure on indentation behavior of carbon fiber reinforced polymer composite sandwich panel (CFRPCSP) with pyramidal truss cores. Composite sandwich panels were fabricated by the hot press molding method. Subsequently, composite sandwich panels were exposed to different temperatures for 6 h. After thermal exposure, quasi-static indentation tests were carried out at room temperature. Then, the effect of thermal exposure on the failure mechanism, indentation load and energy absorption were analyzed and discussed. The results showed that the indentation load and energy absorption decreased as exposure temperature increased, which was caused by the degradation of the matrix properties and fiber-matrix interface properties at high temperature. In addition to the decrease of the indentation load and energy absorption, the failure modes also changed with exposure temperature. It is expected that this study can provide useful information for the design and application of composite sandwich panel with pyramidal truss cores at high temperature.

The effect of temperature on the bending properties and failure mechanism of composite truss core sandwich structures

The effects of temperature on the bending properties and failure mechanism of carbon fiber reinforced polymer composite sandwich structure with pyramidal truss cores were investigated and presented in this paper. The three-point bending tests of composite sandwich structures were performed at seven different temperatures, and the scanning electron microscope was used to examine the fiber-matrix interface properties in order to understand the deformation and failure mechanism. Then the effects of temperature on deformation modes, failure mechanism and bending failure load were studied and analyzed. The results showed that the temperature has visible impact on the deformation modes, failure mechanism, and bending failure load. The bending failure load decreased as temperature increased, which was caused by the degradation of the matrix properties and fiber-matrix interface properties at high temperature. The analytical formulae were also presented to predict the bending stiffness and failure load of composite sandwich structures at different temperatures.

Mechanical behavior of carbon fiber reinforced polymer composite sandwich panels with 2-D lattice truss cores

Composite sandwich structures with lattice truss cores are attracting more and more attention due to their superior specific strength/stiffness and multi-functional applications. In the present study, the carbon fiber reinforced polymer (CFRP) composite sandwich panels with 2-D lattice truss core are manufactured based on the hot-pressing method using unidirectional carbon/epoxy prepregs. The facesheets are interconnected with lattice truss members by means of that both ends of the lattice truss members are embedded into the facesheets, without the bonding procedure commonly adopted by sandwich panels. The mechanical properties of the 2-D lattice truss sandwich panels are investigated under out-of-plane compression, shear and three-point bending tests. Delamination of the facesheets is observed in shear and bending tests while node failure mode does not occur. The tests demonstrate that delamination of the facesheet is the primary failure mode of this sandwich structure other than the debonding between the facesheets and core for conventional sandwiches.

Direct load transmission in hybrid FRP and lightweight concrete sandwich bridge deck

Direct load transmission experiments on hybrid short-span beam specimens for a novel bridge deck were performed. The sandwich construction consists of three layers: a fiber-reinforced polymer composite (FRP) sheet with T-upstands for the bottom skin, lightweight concrete (LC) for the core and a thin layer of ultra high performance reinforced concrete as a top skin. Specimens with adhesively bonded FRP–LC interfaces showed significantly higher ultimate loads than corresponding unbonded specimens with composite action due to pure mechanical interlocking. The degree of composite action between FRP and LC in the unbonded interfaces depended on the LC compressive strength. A correlation of the specimen ultimate loads and the LC splitting tensile strengths was found. Combining the LC splitting tensile strength and the LC characteristic length led to a good correlation with the specimen cracking loads.

Flexural behavior of a hybrid FRP and lightweight concrete sandwich bridge deck

This paper presents a new concept for a lightweight hybrid-FRP bridge deck. The sandwich construction consists of three layers: a fiber-reinforced polymer composite (FRP) sheet with T-upstands for the tensile skin, lightweight concrete (LC) for the core and a thin layer of ultra high performance reinforced concrete (UHPFRC) as a compression skin. Mechanical tests on eight hybrid beams were performed with two types of LC and two types of FRP/LC interface: unbonded (only mechanical interlocking of LC between T-upstands) and bonded with an epoxy adhesive. The ultimate loads of the beams increased by 104% on average due to bonding. However, the beam failure mode changed from ductile to brittle. The beams using a LC of 44% higher density exhibited an 81% increase in the ultimate load. The manufacturing of the beams proved to be economic in that epoxy and concrete layers were rapidly and easily applied wet-in-wet without intermediate curing times. The experimental results showed positive results regarding the feasibility of the suggested hybrid bridge deck.