Characterization of mechanical and dynamic properties of natural fiber reinforced laminated composite multiple-core sandwich plates

Abstract

The present article deals with the study of material, mechanical and dynamic characteristics of natural fiber reinforced composite sandwich plates with multiple-core layers. The multiple-core sandwich structure contains the jute fibers reinforced polymer composites as face layers and the natural rubber and cork as core layer. The material characterization such as X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM) was carried out to investigate the crystallinity, thermal stability, and morphology of untreated and treated jute fiber materials. The tensile and flexural properties of natural composite material was examined using ASTM D3039 and ASTM D7264 standards. The governing equations for the natural fibers reinforced composite sandwich plates are developed using a finite element method. The performance of the developed model is validated by comparing the results available in the published literature. The numerical results indicate that the multiple-core natural composite sandwich plate greatly influences the structural stiffness compared with a single-core natural composite sandwich plate. Furthermore, the influence of core layer configuration, end condition, aspect ratio and ply sequence on the dynamic properties of the multiple-core natural composite sandwich plate are presented.

Introduction

Recent research has demonstrated that lignocellulosic natural fibers such as jute, kenaf, bamboo, and cocos sheath can serve as a promising and sustainable alternative to petroleum-based synthetic fibers. The benefits of using cellulose-based fibers are low density, non-abrasive, high specific mechanical strength, renewable, biodegradable, and cost-effective. Sreekumar et al. [1] investigated the thermal degradation behavior of untreated and 5% NaOH treated sisal fiber and its composites by thermogravimetry method. The study showed that alkali treatment increased the thermal stability and decreased the water intake of treated composites. Further, the SEM and FT-IR analysis revealed that surface treatment altered the morphology and structure of the sisal fibers. Sgriccia et al. [2] investigated the moisture absorption in fiber composites by characterizing the untreated and silane treated hemp and kenaf fibers. The chemical composition of the fiber surfaces was determined using FT-IR. The FT-IR peaks indicated that the saline treatment removed hemicellulose and lignin from the fiber surfaces. Raghavendra et al. [3] carried out to the thermogravimetric analysis to investigate thermal properties of jute fiber incorporated into epoxy matrix. The investigation reveals that incorporating lignocellulose jute fiber into polymer matrix increased the deterioration temperature of the jute/epoxy composite material. Zhang et al. [4] studied the influence of surface treatment on the morphology and thermo-mechanical properties of sodium hydroxide treated bamboo fibers. From the results of FTIR analysis, it is found that the alkalization causes a gradual removal of binding materials from the fiber surfaces. Furthermore, TGA results show that treated samples have better thermal stability than untreated fibers. Fauzi et al. [5] used TGA and differential scanning calorimetric (DSC) analysis to investigate the thermal behaviour of treated and untreated pineapple leaf fibre, kenaf fibre, and mengkuang fibre reinforced epoxy composites. The results showed that treated fibers have a higher degradation temperature than untreated fibers. Devireddy et al. [6] examined the physical and thermal properties of the hybrid composites containing unidirectional banana/jute fiber in epoxy matrix. The authors discovered that the hybrid composites developed have good thermal insulating properties. Jesuarockiam et al. [7] studied the effects of hybridization of various wt% (0.25, 0.5, 0.75) of graphene nano platelets on the thermal stability of kevlar/cocos nucifera sheath/epoxy composites. The authors concluded from the obtained results of thermogravimetic analysis that the hybrid composites could be stable at high temperatures due to the incorporation of graphene platelets, since it acts as a thermal barrier and delayed the degradation. Radzi et al. [8] investigated the thermal properties of roselle/sugar palm reinforced polyurethane hybrid composites using TGA, and the results showed that the hybrid composites with higher sugar palm fiber content had higher thermal stability.

Suthenthiraveerappa et al. [9] determined the tensile, bending, and shear properties of jute and aloe fiber reinforced tapered composite laminates. Further, the elastic constants of the non-uniform composites structures were estimated using the combination of laminate analogy and Halpin–Tsai approach. Singh et al. [10] investigated the effect of alkali treatment with five different concentrations (1%, 3%, 5%, 7%, and 9%) of NaOH solution on the tensile, flexural, and impact characteristics of jute fiber reinforced epoxy composites. It was reported that the composite with 5% NaOH treated jute fibers had higher tensile and flexural strength, whereas the composite with 7% NaOH treated fibers possess maximum impact strength. Lakreb et al. [11] developed the multilayer sandwich panels with aleppo pine wood veneer as inner and surface plies and cork agglomerate as core to investigate the hardness, dimensional stability and discovered that increasing the number of inner layers resulted in a significant enhancement in dimensional firmness, hardness and shear strength of the panels. Loganathan et al. [12] investigated the tensile, flexural, impact, and vibration properties of banana fiber sandwich composites with wire mesh. It was discovered that combining steel wire mesh with banana fibers improved the mechanical and damping properties. Krishnasamy et al. [13] studied the mechanical (tensile, flexural, hardness), vibration, and wear resistance characteristics of composite plates reinforced with aloevera, flax, hemp, wire mesh, and BaSO4 filler in an epoxy matrix and discovered that incorporating steel wire mesh and BaSO4 filler to the plant fibers resulted in an improvement in overall composite laminate properties. Prabhakaran et al. [14] investigated the thermal properties (thermal conductivity, thermal expansion, flammability, and thermal stability) of sandwich composites incorporating flax and agglomerated cork densities of 240, 280, and 340 kg/m³. It is found that the composite with flax and 240 kg/m³ density agglomerated cork core had the lowest thermal conductivity, and the composite with 340 kg/m³ core density offered a minimum propagation rate. Margabandu et al. [15] examined the effects of fabric hybridization and stacking arrangements on the tensile and vibration characteristics of jute-carbon hybrid composites and found that the composites incorporated with jute fabric layers offer a high damping ratio compared to the other composite material.

A typical sandwich structure consists of a lightweight viscoelastic core layer surrounded by two stiff face sheets on top and bottom. The selection of the core layer is critical for effective vibration control. The core layer must be chosen so that it has enough stiffness and damping properties to effectively control vibrations and noises. Sokolinsky et al. [16] investigated the free vibration analysis of sandwich beams with soft polymer foam core using numerical and experimental methods. They concluded that the higher-order shear deformation theory (HSDT) accurately predicts the vibration responses of softcore sandwich beams compared with classical theory and two-dimensional finite element analysis. Banerjee et al. [17] investigated the vibration responses of the beam made of viscoelastic material by using the dynamic stiffness model based on Timoshenko beam theory. Arvin et al. [18] did free and forced vibrations of the composite sandwich beam. It was observed that the loss factors were increased and the natural frequencies decreased with increasing the fiber angles of face sheets and core thickness of the beam. Kumar et al. [19] performed the free vibration test in hybrid sisal-banana polyester composites. They found that the mechanical strength and damping properties are affected by the length and weight percentage of the fibers. Akoussan et al. [20] investigated the damping properties of orthotropic sandwich plates with the viscoelastic core using first-order zig-zag theory. The effect of face layers ply sequence on the natural frequencies and loss factors of the sandwich plates was presented. Daoud et al. [21] analyzed the dynamic properties of composites with unidirectional flax fiber and interleaved viscoelastic layer using experimental and numerical methods. The results showed that with increases in the natural frequency, the damping factors of flax fiber composites are decreased.

Zhai et al. [22] analyzed the dynamic responses of the composite sandwich plate with double-viscoelastic core layers. They concluded that the sandwich plate with double-cores exhibit higher damping than the single-core sandwich plate. Also, the dynamic properties with the effect of various parameters were analyzed. Pandian et al. [23] performed the modal analysis to explore the natural frequency and damping factor of laminates prepared with jute-linen fabrics and different weight fractions of (1, 2 and 3 wt%) silica fumes. The authors discovered that the incorporation of silica fumes beyond 2 wt% reduced the natural frequency of the composites. Waddar et al. [24] examined the effect of cenosphere loading and its surface treatment on buckling and dynamic behaviour of composite beam reinforced with syntactic foam core and sisal fabrics in the epoxy matrix under compressive load. The authors found that the surface-treated cenosphere improved the sandwich beams inherent frequencies and buckling load. Gupta et al. [25] investigated the vibrational properties of cantilever composite sandwich panels made with an aluminium alloy for the surface layers and a natural rubber sheet for the core. They found that the analytical results are in good coherence with the experimental approach. Li et al. [26] developed the mathematical model for the pyramidal lattice truss cores for multilayer sandwich beams and compared with experiments. Selvaraj et al. [27] studied the free vibrations of double viscoelastic core sandwich beam using the ANSYS model and experimental measurements. The results show that the double core sandwich beam enhances the structural stiffness compared with the single-core sandwich beam.

According to the literature review, multiple-core sandwich structures may have a superior structural strength than single-core sandwich structures. Because of its significance, a study of the dynamic properties of the multiple-core sandwich structure was required. However, only a few numerical studies on the dynamic characteristics of multiple core sandwich beams and plates have been published. Furthermore, the dynamic properties of various configurations of natural composite multiple core sandwich structures have not been addressed. This research work investigates the dynamic properties of natural fiber reinforced composite sandwich plates with multiple natural cores. HSDT is used to derive the governing equations for the natural composite sandwich plate. The performance of the developed model is validated by comparing the results available in the published literature. Also, the effects of core configuration, end conditions, aspect ratios, and ply sequence on the dynamic properties of natural fiber reinforced composite multiple core sandwich plates are presented.