Papers by Keyword: Fiber Orientation

Abstract: Hybrid composite laminates that combine Kevlar and glass fibers offer tailored performance, but the interaction between their progressive failure and vibrational behavior remains insufficiently understood. This study employs finite element analysis in ANSYS APDL to evaluate Kevlar/epoxy, glass/epoxy, and Kevlar–glass hybrid laminates with cross-ply and angle-ply stacking sequences, using layered shell elements and the Maximum Stress criterion. The study validates the model against published experimental data and applies it to assess first-ply failure (FPF), last-ply failure (LPF), and natural frequencies. Results show that Kevlar laminates provide the highest strength and natural frequencies, while glass laminates exhibit the lowest, with hybrids consistently demonstrating intermediate performance. Although hybrids record lower FPF than either constituent, their LPF exceeds that of GFRP, reflecting beneficial stress redistribution during damage progression. Natural frequencies decrease systematically with increasing fiber angle, with Mode 2 showing greater sensitivity to orientation. Among the hybrids, H4 provided the most balanced overall performance, pairing competitive LPF with stable modal behavior. This study establishes a clear correlation between failure progression and dynamic response, highlighting the governing role of fiber content and stacking sequence in determining the structural integrity and vibration resistance of hybrid laminates.

Abstract: Composites are materials designed to achieve superior mechanical or physical properties, and understanding both their failure and dynamic behavior is essential. Despite numerous past studies on understanding this behavior of composite materials, information on the interrelationship between these two aspects remains limited. The study aims to conduct a process innovation and provide detailed understanding of the effect of fiber orientation on the Graphite epoxy and E-glass epoxy composite laminates failure behavior and natural frequency and the relationship between the failure and dynamic behavior of these two materials. To achieve this, a process innovation of the simulation of failure analysis and vibration analysis of these composite laminates under uniaxial tensile loading was conducted on 8-ply composite laminates under a lamination scheme of (-θ/45/-45/θ/-θ/45/-45/θ), where θ from 0° to 90°. Finite element models for simulation were developed and validated to ensure the reliability and validity of findings in this study are trustworthy and useful. The results show that both failures loads, and natural frequencies are not much affected by the fiber orientation under this lamination scheme. These two behaviors are also identified to be closely related under specific modes of natural frequency. The detailed effects of failure and natural frequency under fiber orientation and its relation are successfully acknowledged. The findings are expected to support the optimization of laminate design and enhance the structural performance of composite materials in engineering applications and contribute to more informed material selection.

Abstract: In virtual process chains for discontinuous fiber-reinforced polymers, clustering of fiber orientation tensors reduces the number of macroscopic material cards required for downstream structural and warpage simulations. However, it remains unclear whether including the additional information provided by the fourth-order fiber orientation tensor improves clustering quality. This study investigates the influence of second-order vs. fourth-order informed clustering on clustering outcomes and the resulting orientation-averaged mechanical properties. Using parameterizations based on harmonic decomposition, rotation-invariant clustering is performed in both the second-order and fourth-order parameter spaces. Results from injection molding simulation data indicate that the level of tensorial information has limited effect when the fourth-order tensor is computed via a closure approximation, as the deviatoric parameters are nonlinearly dependent on the second-order parameters. In contrast, the choice of clustering algorithm -- KMeans vs. Birch -- has a more pronounced influence on cluster shapes and allocations. Furthermore, we demonstrate that clustering affects orientation-averaged stiffness properties, with deviations most pronounced near cluster boundaries and rarely occurring tensor shapes.

Abstract: Direct compounding of long fiber thermoplastic (LFT-D) materials in compression molding are two complex processes in series linked by the plastificate. Continuous compounding and sequential compression create a time-dependent property progression along the extrusion direction of the plastificate. Under variation of secondary parameters, extruder die temperature, and die height of the LFT-D line, samples of plastificates, flow fronts and plates are manufactured and characterized. The plastificate density progression along the extrusion direction is primarily influenced by the temperature of the die. Lofting of the plastificate is higher at high temperatures while the density difference along the extrusion direction is lower. This density difference is known to influence fiber orientations and mechanical properties. The flow front of the material filling the mold is skewed because of the density difference. We show that the skewness is mainly influenced by the die height and is lower at high die heights. The fiber content distribution in the plate is discussed and found to be influenced by the length of the plastificate which is in turn determined by the secondary parameters. These secondary parameters of the LFT-D line can play a role in process optimization once the primary parameters are selected. This work provides clues and observations of principles for such optimizations.

Abstract: This study addresses the reinforcement of corroded API 5L X42 pipelines using Glass Fiber Reinforced Polymer (GFRP) composite wraps, focusing on optimizing fiber orientation to enhance burst pressure performance. Pipeline corrosion poses significant risks to structural integrity and safety in the oil and gas industry. Experimental burst pressure testing, and Finite Element Method (FEM) were conducted to evaluate unidirectional (0/0/0), bidirectional (0/90/0) and multi-axial (0/45/-45) GFRP wraps. The FEM model, validated against experimental data, showed minimal error with 1.16%. Major findings show that the bidirectional had a maximum stress (501.29 MPa) and burst pressure (44.72 MPa) higher than the unidirectional and multi-axial. Better stress distribution given by the bidirectional structure helped to lower stress concentrations. These results show that pipeline repair techniques can be much improved by orienting fibers correctly. This study found that it helpful in field application of composite repair techniques for corroded subsea pipes.

Abstract: This study examines the feasibility of utilizing the press forming method on multi-layer, multi-orientation continuous CFRP preform produced by the additive manufacturing (AM) technique. The 5-layer preforms with fiber orientations of 45° and -45° impregnated in Nylon-6 resin layers were made by a 3D printer, and press-formed in varying temperatures and pressures. Optimal forming outcomes were determined by qualitative evaluations of the surface finish, fiber impregnation, resin flow, and quantitative observations on shape variations by comparison with the mold dimensions. Experimental results showed that the molding temperature of 220°C and pressure between 0.5MPa - 1MPa could produce preforms with optimal surface conditions. There was almost no void of bubble defects, no excess resin flow, and a smooth transition was established between the carbon fiber and the matrix resin layers while allowing the full mechanical strength properties to be realized. The formed preform evaluations confirmed that the press molding method is feasible on multi-layer, multi-orientation continuous CFRP with optimal surface conditions.

Abstract: A hybrid composite is a combination of two or more reinforced in a matrix. Hybrid composite will give better properties as compared to individual fiber-reinforced polymer composites. This research aims to study the effect of different fiber layer orientations on the properties of hybrid kenaf/fiberglass polyester matrix composite. Two types of the composite were produced which are Sample 1, the fiber layer orientation is fiberglass, kenaf fiber, kenaf fiber and fiberglass (FG-K-K-FG), and Sample 2, the fiber layer orientation is fiberglass, kenaf fiber, fiberglass, and kenaf fiber (FG-K-FG-K). The composite is manufactured using the hand lay-up technique and hot pressed. 50 g of unsaturated polyester resin and 12 g of hardener, Methyl Ethyl Ketone Peroxide (MEKP) were mixed and applied on top of every layer of fiber before being compressed at 100°C for 10 minutes. The properties of the hybrid composite were determined by completing five types of tests which are tensile test, impact test, water absorption test, thermogravimetric analysis (TGA), and scanning electron microscope (SEM). The results showed that Sample 2 (FG-K-FG-K) has higher tensile strength compared to Sample 1 (FG-K-K-FG) with the value of 30.97 MPa and 0.23 MPa respectively. For the water absorption test, Sample 1 (FG-K-K-FG) with a value of 239.21% has the highest water absorption properties compared to Sample 2 (FG-K-FG-K) with a value of 180.22%. Samples 1 and 2 have no obvious differences in terms of their thermal stability characteristics for the TGA test. For SEM, it is observed that both samples showed an attachment of adhesive between fiber layers and matrix. The overall conclusion is Sample 2 (FG-K-FG-K) has high mechanical properties but needs improvement for low water absorption.

Abstract: The paper reported the study on the tensile strength of polymer composite reinforced with abaca fiber and polyester matrix. The effect of fiber weight content and fiber orientation on the tensile strength of the abaca composite were investigated in the study. The abaca composite panel was fabricated using press method with 3 levels of the fiber weight content (20%, 30% and 40%) and 3 levels of fiber orientation (0⁰, 45⁰ and 90⁰). The tensile specimen was prepared according to ASTM D3039 standard. The tensile test was conducted using MTS Landmark servo hydraulic testing machine with a tensile speed of 2 mm/min. The result of the experiment showed that both of fiber weight content and fiber orientation gave significant effect on the tensile strength of the abaca composite. The highest tensile strength was 61.9 MPa, produced by the abaca composite panel with fiber weight content 30% and fiber orientation 0⁰. According to the standard, the tensile strength has fulfilled the requirements as a non-structural material.

Abstract: A material (polymer + glass fibers) is characterized by its inhomogeneity and anisotropy. This material is subjected an injection molding simulation at first (generally unnewton type of fluid). Then the material is cooled and common structural analysis (static, dynamic and thermal) is performed. The cooled material has dissimilar mechanical properties for each of discrete element. Thus the mechanical properties (after simulation of load) will completely have different values when influence of injection molding is included.

Abstract: The objective of this work is to study the fiber orientation effect on frictional material properties and tribology performance. Effects of orientation on hardness, maximum load capacity under bending, the friction coefficient and surface wear of the composites were investigated. In this research, 3D printing technique was used to create workpieces in order to control fiber arrangement which is random, 0, 45, and 90 degrees. The results suggested that the fiber direction insignificantly affects material hardness with all specimen showing similar value of average hardness of approx. 90 HRC. However, the fiber orientation had a strong influence on material bending strength. The specimen with forced fiber orientation showed lower bending resistance compared to that with random fiber orientation. This may be caused by the non-uniform distribution of fiber which could promote fracture initiation site in some area with low fiber density. The coefficient of friction of the composite material was found to strongly related to it wear behavior, i.e. higher wear rate results in higher value of friction coefficient. The wear resistance was found to be controlled by both the fiber direction and fiber interface. With fiber oriented at 90 degree to sliding direction, higher coefficient was observed. However, as surface wear took place, the effect of wear debris results in an increase in friction coefficient. For 3D printed specimen, wear was increased with fiber interface density resulting in higher wear rate of specimen with 0-degree fiber orientation compared to those with 45-and 90-degree orientation during. Hence, the specimen with 0 degree fiber direction showed similar value of coefficient of friction to those with random and 90 degree fiber orientation.