Varying Fiber Orientations Research Articles

Modeling fiber orientation and strand shape morphology in three-dimensional material extrusion additive manufacturing

The fiber orientation in composite materials is highly dependent on the manufacturing process and plays a crucial role in determining the mechanical, thermal, and electrical properties of the fabricated parts. Several simulation frameworks have been developed to predict the fiber orientation in the printed strands for Material EXtrusion Additive Manufacturing (MEX-AM) process, but studies have been limited to planar and 2D model reductions. Consequently, it is currently impossible to predict the full spatial variation of fiber orientations in a three-dimensional printed strand, and thus the effects of printing conditions remain not well understood. This work seeks to address this issue by introducing the first three-dimensional model capable of simulating the MEX-AM process with fiber-reinforcements. A fully coupled model is developed in this work, which is based on the finite-volume method and solved in the open-source multiphase software OpenFOAM. Using this framework, we explored the effects of different printing conditions on fiber orientation and strand shape morphology, and we compared our results to experimental observations when possible. We found that the extrusion and nozzle velocities significantly affected the fiber orientation while altering the gap distance between the nozzle exit and substrate had a limited impact. Moreover, increasing anisotropy using longer fibers and higher volume fractions had little influence on the fiber orientation, but their impact on the rheology altered the strand shape considerably. Prediction of fiber orientation for different printing conditions within strands will open the possibility of manufacturing products that has locally engineered properties and tailored anisotropic behavior.

Fiber Orientation Quantification for Large Area Additively Manufactured Parts Using SEM Imaging.

Polymer-based additively manufactured parts are increasing in popularity for industrial applications due to their ease of manufacturing and design form freedom, but their structural and thermal performances are often limited to those of the base polymer system. These limitations can be mitigated by the addition of carbon fiber reinforcements to the polymer matrix, which enhances both the structural performance and the dimensional stability during cooling. The local fiber orientation within the processed beads directly impacts the mechanical and thermal performances, and correlating the orientation to processing parameter variations would lead to better part quality. This study presents a novel approach for analyzing the spatially varying fiber orientation through the use of scanning electron microscopy (SEM). This paper presents the sample preparation procedure including SEM image acquisition and analysis methods to quantify the internal fiber orientation of additively manufactured carbon fiber-reinforced composites. Large area additively manufactured beads with 13% by weight large aspect ratio carbon fiber-reinforced acrylonitrile butadiene styrene (ABS) pellets are the feedstock used in this study. Fiber orientation is quantified using the method of ellipses (MoE), and the spatial change in fiber orientation across the deposited bead cross-section is studied as a function of process parameters including extrusion speed, raster height, and extrusion temperature zones. The results in the present paper show the results from the novel use of SEM to obtain the local fiber orientation, and results show the variation in alignment within the individual processed bead as well as an overall aligned orientation state along the direction of deposition.

A FEM Free Vibration Analysis of Variable Stiffness Composite Plates through Hierarchical Modeling

Variable Angle Tow (VAT) laminates offer a promising alternative to classical straight-fiber composites in terms of design and performance. However, analyzing these structures can be more complex due to the introduction of new design variables. Carrera’s unified formulation (CUF) has been successful in previous works for buckling, vibrational, and stress analysis of VAT plates. Typically, one-dimensional (1D) and two-dimensional (2D) CUF models are used, with a linear law describing the fiber orientation variation in the main plane of the structure. The objective of this article is to expand the CUF 2D plate finite elements family to perform free vibration analysis of composite laminated plate structures with curvilinear fibers. The primary contribution is the application of Reissner’s mixed variational theorem (RMVT) to a CUF finite element model. The principle of virtual displacements (PVD) and RMVT are both used as variational statements for the study of monolayer and multilayer VAT plate dynamic behavior. The proposed approach is compared to Abaqus three-dimensional (3D) reference solutions, classical theories and literature results to investigate the effectiveness of the developed models. The results demonstrate that mixed theories provide the best approximation of the reference solution in all cases.

Optimization of 3D printing and in vitro characterization of alginate/gelatin lattice and angular scaffolds for potential cardiac tissue engineering.

Background: Engineering cardiac tissue that mimics the hierarchical structure of cardiac tissue remains challenging, raising the need for developing novel methods capable of creating structures with high complexity. Three-dimensional (3D)-printing techniques are among promising methods for engineering complex tissue constructs with high precision. By means of 3D printing, this study aims to develop cardiac constructs with a novel angular structure mimicking cardiac architecture from alginate (Alg) and gelatin (Gel) composite. The 3D-printing conditions were optimized and the structures were characterized in vitro, with human umbilical vein endothelial cells (HUVECs) and cardiomyocytes (H9c2 cells), for potential cardiac tissue engineering. Methods: We synthesized the composites of Alg and Gel with varying concentrations and examined their cytotoxicity with both H9c2 cells and HUVECs, as well as their printability for creating 3D structures of varying fibre orientations (angular design). The 3D-printed structures were characterized in terms of morphology by both scanning electron microscopy (SEM) and synchrotron radiation propagation-based imaging computed tomography (SR-PBI-CT), and elastic modulus, swelling percentage, and mass loss percentage as well. The cell viability studies were conducted via measuring the metabolic activity of the live cells with MTT assay and visualizing the cells with live/dead assay kit. Results: Among the examined composite groups of Alg and Gel, two combinations with ratios of 2 to 1 and 3 to 1 (termed as Alg2Gel1 and Alg3Gel1) showed the highest cell survival; they accordingly were used to fabricate two different structures: a novel angular and a conventional lattice structure. Scaffolds made of Alg3Gel1 showed higher elastic modulus, lower swelling percentage, less mass loss, and higher cell survival compared to that of Alg2Gel1. Although the viability of H9c2 cells and HUVECs on all scaffolds composed of Alg3Gel1 was above 99%, the group of the constructs with the angular design maintained significantly more viable cells compared to other investigated groups. Conclusion: The group of angular 3D-ptinted constructs has illustrated promising properties for cardiac tissue engineering by providing high cell viability for both endothelial and cardiac cells, high mechanical strength as well as appropriate swelling, and degradation properties during 21days of incubation. Statement of Significance: 3D-printing is an emerging method to create complex constructs with high precision in a large scale. In this study, we have demonstrated that 3D-printing can be used to create compatible constructs from the composite of Alg and Gel with endothelial cells and cardiac cells. Also, we have demonstrated that these constructs are able to enhance the viability of cardiac and endothelial cells via creating a 3D structure mimicking the alignment and orientation of the fibers in the native heart.

The Influence of Fiber Orientation and Treatment Variation of Natural Fiber Reinforced Composites on Tensile Strength and Toughness

Composites using natural fibers are being widely developed and researched, this is because natural fibers are easy to find and abundant. In this study, the natural fibers used were bamboo fiber and banana stems. Banana fiber has good mechanical properties and is easy to find, while bamboo fiber is easy to find and has a low density. In this study, the aim was to determine the effect of fiber orientation and treatment on the tensile strength and toughness of natural fiber reinforced composites using a polyester matrix. The variation of the fiber orientation used is 30o and 90o, and the fiber treatment used is alkali and bleaching treatment. Based on the research results, the 90o angle with fiber bleaching treatment has the highest tensile strength value, which is equal to 37.33 MPa with a modulus of elasticity of 5 GPa. As for toughness through impact testing, the highest value is 2.74 x 10-2 J/mm2 at an angle of 90o with bleaching treatment.

Axon fiber orientation as the source of T1 relaxation anisotropy in white matter: A study on corpus callosum in vivo and ex vivo.

Recent studies indicate that T1 in white matter (WM) is influenced by fiber orientation in B0 . The purpose of the study was to investigate the interrelationships between axon fiber orientation in corpus callosum (CC) and T1 relaxation time in humans in vivo as well as in rat brain ex vivo. Volunteers were scanned for relaxometric and diffusion MRI at 3 T and 7 T. Angular T1 plots from WM were computed using fractional anisotropy and fiber-to-field-angle maps. T1 and fiber-to-field angle were measured in five sections of CC to estimate the effects of inherently varying fiber orientations on T1 within the same tracts in vivo. Ex vivo rat-brain preparation encompassing posterior CC was rotated in B0 and T1 , and diffusion MRI images acquired at 9.4 T. T1 angular plots were determined at several rotation angles in B0 . Angular T1 plots from global WM provided reference for estimated fiber orientation-linked T1 changes within CC. In anterior midbody of CC in vivo, where small axons are dominantly present, a shift in axon orientation is accompanied by a change in T1 , matching that estimated from WM T1 data. In CC, where large and giant axons are numerous, the measured T1 change is about 2-fold greater than the estimated one. Ex vivo rotation of the same midsagittal CC region of interest produced angular T1 plots at 9.4 T, matching those observed at 7 T in vivo. These data causally link axon fiber orientation in B0 to the T1 relaxation anisotropy in WM.

Optimization design of variable stiffness composite cylinders based on non-uniform rational B-spline curve/surface

Compared with a constant stiffness (CS) composite structure of traditional straight fiber path, a variable stiffness (VS) composite structure of curvilinear fiber path has a broader design space. Taking the performance of a CS cylinder as the baseline, two curved fiber formats of VS cylinders are investigated. One is that the fiber angle varies in circumferential direction (i.e., circumferential stiffness variation, VS-C), the other is that the fiber angle varies in both circumferential and axial directions (i.e., circumferential and axial stiffness variation,VS-CA). Non-uniform rational B-spline curve/surface is used to define the continuously varying fiber orientation angle, making the VS design come true. This paper focuses on the maximum buckling capacity of VS composite cylinders under two kinds of loading cases (pure bending moment at both ends, concentrated force at the middle of the axis), and the optimal fiber angles of VS-C and VS-CA cylinders are obtained. In order to improve the computational efficiency, the adaptive Kriging surrogate model is integrated with genetic algorithm to solve the above optimization problems. The results show that the anti-buckling performance of VS-CA structure is always better or close to VS-C structure under different loading conditions, and all are better than that of CS structure.

ガラス短繊維強化PPS樹脂の繊維配向分布を考慮したマイクロメカニックスに基づくX線応力評価

The stress in polyphenylene sulfide (PPS) resin reinforced by glass fibers of 26 mass% was measured by the diffraction method using synchrotron with energy of 18 keV. The stress in the matrix was determined by the sin2ψ method with iso-inclination optics of transmitted X-ray diffractions. Tensile coupon specimens were cut from the skin-layer of injection molded plates in three directions, parallel, perpendicular and 45°, to the molding direction. The matrix stresses in the loading and transverse directions of specimens were measured under several uniaxial applied stresses. They changed proportionally to the applied stress. The proportional constants of the matrix stresses to the applied stress were determined, and named the stress-partitioning coefficients. The elastic constant and the matrix stress of the composite were calculated theoretically using micromechanics for two cases of fiber orientation: unidirectional (UD) and varied orientation distribution (VD). Fiber orientation tensor was determined from microscopic measurement of the cross-sectional shape distribution of fibers. Compared with the calculation based on UD fiber orientation, the analytical values based on micromechanics considering the variation in fiber orientation are closer to experimental values of elastic constants and stress-partitioning coefficients.

Surrogate model assisted design optimization of composite bone plates to achieve selective stress shielding

ABSTRACT Optimal composite bone plate is designed for Periprosthetic Femoral Fracture (PFF) fixation using genetic algorithm (GA) by hybrid and varying fiber orientation. The bone plate should allow higher displacement in axial direction and minimum movement in shear direction. Composite material is considered for the bone plate, the most important constraint in this design problem is that the axial movement and shear movement are limited to 2 and 0.5 mm, respectively. The simulated data from the finite element analysis (FEA) are used for creating the artificial neural network (ANN) surrogate models for the bone displacements in both the directions, which act as the objective functions for the GA-driven optimization in the multi-objective fashion. FEA is used to validate the solutions derived through the design optimization process. The FE simulations have shown only 10% deviation in the simulation output when compared to the achieved optimum solutions.

Stress analysis of adhesive-bonded tubular-coupler joints with optimum-stiffness-composite adherend under axial tension, pressure, and thermal loading

With descriptions of fiber orientation variation, variable-stiffness composites (VSCs) have opened many new opportunities for structural designs because they offer tailorable material properties to increase the performance of composite structures. Using the concept of VSCs, this study aimed to determine the optimum adhesive-bonded tubular coupler joints subjected to tension, pressure, thermal load, and/or combinations thereof. The joint consists of three axisymmetric cylindrical adherends. The two inner adherends are made of a linear elastic isotropic material, whereas the outer adherend is composed of a symmetric balanced laminate. As the most complicated cases among others, owing to various stress components induced in the adherends and adhesive, the joints under these dominant in-plane normal force loadings are modeled to efficiently minimize stress concentrations in the thin adhesive layer. The unified theory of adhesive-bonded tubular joints was modified one step further to compute the optimum fiber angle variation using the constraint of linear distribution of the axial resultant forces in the adherends. From the methodological viewpoint, the results unveiled that the interfacial shear stress concentration in the adhesive layer was considerably diminished or even vanishes under all loading scenarios. The possibility of multiple optimum composite joints can be achieved, which otherwise are not straightforward to determine when using other analytical tubular joint models and optimization methods. Parametric studies of geometrical variables were also performed to provide a design guideline for optimum coupler joints with efficient mitigation of peak adhesive interfacial stresses.

Experimental Analysis of Transseptal Puncture to Investigate the Mechanical Properties of Fossa Ovalis

Background/Objective: Optimization of needle characteristics for trans-septal puncture is of paramount importance to reduce the extent of tissue deformation. This was achieved by studying the mechanical behavior of fossa ovalis (FO) in lamb hearts. The fossa ovalis tissue samples obtained after dissection were subjected to experimental indentation and tensile tests to determine tissue deformation. Methods: Lamb hearts (n = 20) were dissected to obtain fossa ovalis tissue samples. These were subjected to indentation and tensile tests to determine the puncture and rupture forces respectively. Indentation tests were performed using two different indenters: A steel indenter with a hemispherical tip and a Brockenbrough (BRK) needle (bevel tip). Tensile tests were formed using Zwick Roell (Z005) tensile machine at 100 N load cell. ImageJ analysis was also performed to determine the diameter and shape of FO. Results: Indentation results demonstrated that the hemispherical indenter requires a greater punch force compared to the puncture force with the BRK needle. The mean punch force of the hemispherical indenter (15.57 N) was nearly 3 times greater than the puncture force of the BRK needle (5.47 N). Variations between the two indenters provide an insight into the importance of device geometry on trans-septal procedures. The tensile test results illustrated a typical failure pattern with a toe region, linear region, and failure region. The mean rupture force determined was 10.51 N. ImageJ analysis confirmed an oval shape of FO and the diameters measured were in the range 9.0–15.3 mm. Conclusions: The mechanical aspects of fossa ovalis in lamb hearts were successfully studied through a series of experimental indentation and tensile tests. This study serves as a guide to dissecting the challenging FO sample. The procedures for indentation and tensile tests are detailed with common experimental challenges encountered addressed. The correlation of the parameters involved in these experimental tests to the collagen fiber orientation in tissues is also discussed, providing an insight into the deformation of tissues and variations in fiber orientation before and after trans-septal procedures.

Pengaruh Fraksi Volume dan Orientasi Serat Pada Komposit Hibrid Berpenguat Serat Gambas serta Eceng Gondok Terhadap Kekuatan Bending

Wood is increasingly difficult to obtain due to the use of excess wood. Many efforts were made to replace wood, one of which was composite material. This study aims to determine the most optimal bending strength with the influence of variations in volume fractions and fiber orientation in hybrid composites with luffa fibers and hyacinth fibers. In making composites using the hand lay-up method with alaklization treatment on gambas and hyacinth fibers using 5% NaOH which is varied with the volume fraction used in this study with the ratio of resin: hyacinth: gambas is (60%:20% :20%),(70%:15%:15%), as well as (80% :10%:10%) and the orientation of the fibers with the arrangement of the luffa / hyacinth / luffa layer is (0°/ 45 °/ 90°), (0˚/45˚/0˚), (90˚/0˚/90˚). Bending testing was performed with ASTM D790 standard and hypothesis testing using the two-way ANOVA method. From the results of bending testing, the most optimal strength value was found, which was 43.33 N / mm2, where the value was not higher than the bending strength value in the multiplex, which was 17.53 N / mm2. Meanwhile, the results of hypothesis testing are that there is an influence on the volume fraction factor, the direction of fiber orientation and the interaction with bending forces.

Simplified FE model and experimental study on the tensile properties of the glass fiber reinforced polyester polymer

This research aims to understand the simplified finite element (FE) model behavior for estimating the glass fiber reinforced polyester polymer (GFRP) structural response and studying its tensile properties. The simplified FE model has been developed using an equivalent single-ply transversely isotropic material model to estimate the multi-layer GFRP laminates tensile behavior. The linear elastic and a trilinear plasticity material formulation were adopted. The experimental study is conducted to determine the tensile properties of the equivalent single-ply model of the multi-layer laminates with the variation of layers number, stacking sequence, and fiber orientation. The tensile test specimen used E-glass fiber reinforcement and polyester resin (Yukalac 157 BQTN-EX) as the matrix. The hand layup method was used for the lamination procedure. The experimental results show that the nonlinearity might occur due to the imperfection and poor quality of the composite laminate. Therefore, the comparison of numerical simulation and the experimental results is conducted to understand the stress-strain behavior of the simplified FE model. Both models presented different characteristics and showed good agreement with the experimental results. The linear model can be adopted while the nonlinearity is not significantly identified. Furthermore, the plastic strain as a compensated constant should be defined thoroughly to conduct an accurate estimation using the trilinear plasticity model. However, neither model is suitable for predicting the composite laminate’s initial failure point.

Frontal Polymerization in Short-Fiber-Reinforced Thermoset Composites

Frontal polymerization (FP) has recently been introduced as a faster, more energy-efficient manufacturing process for high-performance thermoset composites. This numerical study focuses on the FP-based manufacturing of short-fiber-reinforced polymeric matrix composites. The investigation involves a combination of multiphysics finite element analyses and analytical predictions. The developed model is also applied to a short-fiber composite with spatially varying fiber orientation obtained from a sample produced by vacuum injection method. The results show how the steady-state front velocity and inclination angle depend on the fiber orientation angle and volume fraction. Analytical expressions are derived to capture that dependence and show excellent agreement with the numerical steady-state results. Simulations of FP in short-fiber composites based on experimental distributions of the fiber orientation indicate the feasibility of FP in samples prepared by injection molding.

Estimation of dynamic characteristics of a wind turbine blade

Wind energy is considered a clean source of energy that can be used efficiently to produce electricity without any harmful emissions. A wind turbine is an electro-mechanical system that converts the wind's kinetic energy into electricity. A typical wind turbine consists of three components, viz. the rotor (which includes the turbine blades), generator and the supporting structure. The turbine blades are a critical component of any wind turbine. They comprise of numerous airfoil sections with varying chord lengths and twist angles, that are combined together to form a three-dimensional blade surface. When generating electrical power through rotating motion, they are subjected to different loads, such as wind, gravitational, and centrifugal loads. The sheer size of the turbine blade necessitates the use of light and strong materials, and composites are well suited for this. The selection and manufacturing of suitable composite material is critical to blade design as it directly affects the efficiency and power of wind power plants. With blades that are continuously exposed to large wind loads, it is essential to determine the natural frequencies of vibrations at which they occur and understand the consequences. Large amplitude vibrations can induce dynamic stresses and accelerate the fatigue of the blade material leading to blade breakage. Thus, it is of significant importance to analyse the dynamic behaviour of these structures. This study aims to investigate the effect of varying fiber orientation and volume fraction on natural frequencies and vibration modes of the turbine blade.

Structural integrity evaluation of cyclic loading Glass Fibre Reinforced Polymer composite by acoustic emission and heat transfer

GFRP composites experience structural changes like matrix cracking, debonding, delamination, and fibre failure on static and dynamic loading. In this work, composites with varying fibre orientation interaction angle and volume fractions are prepared and exposed to cyclic load. The cyclic load (R = 0) is a constant amplitude flexural load imposed on the cantilever beam specimen with varying frequencies (2.6, 4.6, 8.6 Hz) and cycles (up to 44 × 103). The structural integrity of the specimens on loading is examined in terms of Flexural, modulus, Acoustic Emission (AE) and heat transfer changes. The drop in flexural modulus is minimum in higher Vf = 32% laminate (A1 = 7.01%, B1 = 1.86%) than the lower Vf = 25% (A2 = 19.86%, B2 = 8.6%). The observed AE peak frequency for the induced damages is in the range of 50–100, 110–230, 245–380 kHz. The drop-in fibre volume fraction has a significant role in laminate with lower fibre interaction (Type A) to offer minimum variation (5.25%) in AE activity count which is the opposite in laminates with higher fibre interaction angle (31.75%). The step heat thermography exhibits minimum temperature difference (∆T) for moderate loading frequency and in a few cases, ∆T drops well below the virgin, insisting on in situ thermography to study the dynamic changes in composites. A fibre dominant behaviour can be observed with minimum variation in AE activity in a lower fibre interaction angle. Thus, the fibre orientation angle and fibre volume fraction have a significant role in the retention of the structural integrity of composites in dynamic loading.

Composite Overwrapped Pressure Vessel Design Optimization Using Numerical Method

Composite Overwrapped Pressure Vessels (COPVs) are widely used in fields including aeronautics and by companies such as SpaceX to hold high pressure fluids. They are favored for these applications because they are far lighter than all-metal vessels, although they demand special design, manufacturing, and testing requirements. In this study, finite element modeling was used to conducted stress and damage assessments on a composite overwrapped pressure vessel that has a 4 mm thick aluminum core cylinder. To develop the optimum COPV, the lamina sequences, thickness, and fiber winding angle were considered. The relationship between these variables and the composite-overwrapped structure’s maximum burst pressure bearing capacity was assessed. The ABAQUS composite modeler was used to design and generate 14 models of COPVs from carbon fiber/epoxy plies with a consistent thickness of 6.5 mm and various fiber angle orientations. The effects of the ply stacking order were analyzed by the finite element analysis approach for all designed models, which had 13 layers of uniform thickness but a varying fiber orientation. A ply stacking sequence of [55°, −55°] PP winding pattern had an optimum COPV design profile, with a burst pressure bearing capacity of 24 MPa. The stress–strain distribution along the geometry of the COPV was also obtained using the finite element method, and it was found that the distribution is uniform over the surface of the COPV and that its peak values are found towards the polar boss section of the COPV. Extreme stress gradients were noticed when the boss nears its geometrical transition to the dome phase. This factor is evident from the change in the ply thickness caused by the overlapped fiber orientation. The results obtained from this study are useful for the design and application of composite overwrapped pressure vessels.

The influence of composite bone plates in Vancouver femur B1 fracture fixation after post-operative, and healed bone stages: A finite element study

Conventional stainless steel or titanium plates are used for bone fracture fixation to provide support at fracture location. Plates with high elastic modulus reduce the transfer of compressive load at the fracture location (due to stress shielding), causing failure. The objective of the study is to find for composite bone plates with different types of fibers and varied fiber orientations for post-operative (PO) and healed bone (HB) conditions which can reduce the stress shielding. Femur fracture fixation was constructed with 12 holes narrow type with metal and composite bone plates. The fracture gap was constructed with soft bone region for post-operative (PO) condition and harder bone for healed bone (HB). Composite bone plates with different configurations (fiber directions) and types (thickness and width) were analyzed to study the stress distribution and movement in the fracture location. The models were analyzed and the stresses in plate and callus, movement and strain in axial and shear direction in both metal and composite bone plates were studied. The metal and composite plates (carbon fiber/epoxy, fiberglass/epoxy, and flax/epoxy) used for most common Vancouver type B1 fracture to observe the biomechanical behavior of different models in PO and HB condition. The FE simulation on different configurations and types of composite plates provide in-depth idea about choosing the suitable composite bone plate. There are variations in behavior for varying types and configurations, but the performance of most of the plates are either better or similar to that of metal plate, except the plates with higher width.

Off-Axis and On-Axis Performance of Novel Acrylic Thermoplastic (Elium®) 3D Fibre-Reinforced Composites under Flexure Load.

The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that the on-axis specimens show linear response and brittle failure; in contrast, the off-axis specimens depicted highly nonlinear response and ductile failure. The thermoplastic on-axis specimen exhibited almost similar flexure strength; in comparison, the off-axis specimens show ~17% lower flexure strength compared to thermoset 3D-FRC. Thermoplastic 3D-FRC shows ~40% higher energy absorption, ~23% lower flexure modulus and ~27% higher flexure strains as compared to its thermoset counterpart.

Effects of Moisture Absorption and Thickness Swelling Behaviors on Mechanical Performances of Carica Papaya Fiber Reinforced Polymeric Composites

ABSTRACT In this study, composite materials were made from Carica papaya fibers (CPFs), as a reinforcing element in polypropylene (PP), polyester (P) and epoxy (E) matrices, using compression molding technique. Experiments were conducted to evaluate the input parameters with their output responses, specifically density and thickness. Various CPF reinforced PP, P, and E composite specimens with varied fiber orientations of 0°, 45°, and 90° as well as percentages of fiber contents of 10, 20, and 30 wt.% were prepared, according to the ASTM D 570 standard. From the results obtained, it was observed that CPF/E composites with fewer fraction of CPF and orientation of 90° exhibited less water absorption throughout the whole duration of immersion. Water saturated CPF/E composite specimen, designated as E8, with orientation of 0° and fiber content of 20 wt.% showed the highest tensile, flexural strengths, and Shore D Hardness of 119, 115 MPa, and 85, respectively. Also, CPF/E composite specimen (E7) with 90° and 10 wt.% recorded the lowest tensile strength of 32 MPa, and CPF/E composite (E3) with 90° and 30 wt.% showed the lowest flexural strength of 41 MPa. Hence, it was evident that optimum CPF reinforced polymeric composite can be used for some outdoor engineering applications.