Properties Of Laminates Research Articles

Experimental investigation on low-velocity impact and compression after impact behaviors of GFRP laminates with steel mesh reinforced

Abstract This article aims to evaluate the effects of mesh size change on the mechanical properties of GFRP laminates, via low-velocity impact and compression-after-impact (CAI) test, and the failure mechanism was analyzed. Through vacuum-assisted resin infusion, wire meshes with different mesh numbers and wire diameters were incorporated into GFRP. Based on response history and failure morphology, the results show that the addition of wire mesh can disperse the incident energy from the impact center to the outer region, thereby improving the impact resistance of GFRP. It is worth noting that increasing the number of mesh could improve the stiffness of the panels and enhance their ability in CAI events compared with increasing the diameter of wires, their failure evolution was presented from the perspective of digital image correlation (DIC). For example, the maximum displacement of 0.50–40 J decreased by 10.6% from 2.5 to 2.26 mm compared with 20–60 J.

An induction curing technique for CFRP laminate via magnetic particle‐induced in situ heating

AbstractCuring high‐performance carbon fiber reinforced polymer (CFRP) structures with economical and energy‐efficient off‐oven techniques is important for the widespread application of the composite. In this work, we reported a magnetic particle‐induced in situ heating method to controllably cure CFRP laminates with stacking sequences of [0]8, [0/90]4s and [0/45/90/−45]2s. Results showed that all the laminates can undergo a consistent, layup‐independent two‐staged heating protocol via regulating the magnetic field intensity. Under the same curing protocol, the three stacking‐sequenced CFRP laminates can be cured more completely under induction heating than oven heating, in addition to a moderately improved tensile and flexural properties. However, the porosity of the laminates slightly increased under induction heating. The proposed new curing method provides a new avenue to the fabrication of advanced CFRP composite structures without oven or autoclave.Highlights A particle‐induced in situ heating method to controllably cure carbon fiber reinforced polymer (CFRP) laminates was proposed. This method was capable to cure CFRP laminates with different stacking sequences. Mechanical property of laminates was moderately improved under this method.

The Effect of Adhesive Quantity on Adhesion Quality and Mechanical Characteristics of Woven Kevlar Fabric-Reinforced Laminated Structures

This study investigated the adhesion and mechanical properties of woven fabric-reinforced laminates (FRLs) made with four distinct Kevlar fabrics of varying areal densities (36 g/m2, 60 g/m2, 140 g/m2, and 170 g/m2) under different fabric-to-adhesive weight ratios (1:0.5, 1:1, and 1:1.5) in both the warp and weft directions. A novel aspect of this research lies in our systematic study of the effect of adhesive quantity on FRLs, a topic that has received limited attention despite its critical role in laminate performance. Additionally, the application of a newly developed yarn pullout test alongside the standard T-peel test provides unique insights into the interfacial behavior of laminates. The results show that in lower areal density fabrics (36 g/m2 and 60 g/m2), adhesive quantity minimally affects the pullout and T-peel forces or tear strength, indicating that structural integrity can be maintained with reduced adhesive application. In contrast, higher areal density fabrics (140 g/m2 and 170 g/m2) benefit from an increased adhesive ratio, with a transition from 1:0.5 to 1:1 significantly enhancing the pullout resistance, while further increases to 1:1.5 yielded diminishing returns. Tensile strength remained consistent across all samples, highlighting that it is largely dictated by the inherent properties of the fibers and fabric structure rather than the adhesive. This study concludes that a 1:1 fiber-to-adhesive ratio offers an optimal balance of adhesion quality and mechanical performance for FRLs. By addressing the understudied impact of adhesive quantity on FRLs and introducing the yarn pullout test, this research provides novel and practical guidelines for optimizing FRLs in applications demanding high structural integrity and adaptability under challenging conditions.

Tensile Properties of Scarf-Repaired Composite Laminates with Bonding Defects

Tensile Properties of Scarf-Repaired Composite Laminates with Bonding Defects

Influence of plate vibration on delamination formation in composites under multiple impacts

Dynamic vibration is believed to be a basic property of the impacted composite laminates; however, its effect on delamination formation requires further investigation. This study proposes a numerical model in collaborating with ABAQUS, which was calibrated using experimental results, to investigate the effect of plate vibration on delamination formation in composite laminates subjected to two consecutive identical ice or steel projectile impacts with a fixed loading distance. The only variable parameter for the different simulations was the time interval between the two impacts. The loading condition considered in this study is an extreme case where the composite laminate was still vibrating after the first impact when the second impact occurred. The results showed that the delaminations that formed later were significantly affected by the time intervals of the two identical successive ice or steel projectiles. As the vibrated impact points travel from the minimum peak to the adjacent maximum peak during the first vibration period, the newly formed delamination areas monotonically increase with time and vice versa. The change in the maximum contact forces of two identical impacts induced by dynamic vibration is suggested to be a major reason for the discrepancy between the newly formed delamination and previous ones.

Predicting transverse thermal conductivity of flax-fiber using micromechanical model based inverse framework

The paper presents an inverse approach using a micromechanical model for predicting the transverse thermal conductivity of flax fiber, addressing the lack of standard testing protocols for characterizing natural fibers. The model predicts the transverse thermal conductivity of the fiber from experimentally measured properties of the flax-epoxy lamina. The inverse approach was validated using data corresponding to carbon-epoxy composite reported in the literature, with an error of less than 5 %. The transverse thermal conductivity of the flax fiber was estimated to be 0.87 W/m K, which is comparable to other natural fibers. The flax fiber properties were used to evaluate the thermal conductivity of the flax-epoxy lamina for a range of volume fractions, and a simplified non-linear regression equation was proposed. The methodology is further extended to predict the elastic properties of the woven fabric laminate using a multiscale homogenization approach. The proposed framework offers a reliable method for predicting the thermal properties of flax-epoxy composites, which forms the basis for thermo-mechanical analysis and design of automotive and aerospace components.

Mechanical Behavior of Thin Ceramic Laminates on Central Incisors.

Restorative dentistry often uses ceramic laminate veneers for aesthetic anterior teeth restorations due to their natural appearance and minimal invasiveness. However, the understanding of their clinical performance and how ceramic microstructure and processing affect longevity is limited. Objective: This study aimed to address this gap by determining the mechanical behavior, fracture load, and failure modes of CAD-CAM processed laminate veneers made of either lithium-disilicate-based glass ceramic (IPS e.max CAD) or feldspathic porcelain (Vita Mark II). It also aimed to develop a mechanical cycling methodology capable of determining the lifetime and failure modes of thin ceramic laminate veneers. Materials and Methods: Eighteen human maxillary central incisors were used to create the specimens. Minimal enamel preparation was required to ensure the proper adaptation of the thin ceramic laminates. Ceramic laminates made from lithium disilicate and feldspathic porcelain (Vita Mark II) were produced via CAD-CAM, with the final thicknesses less than 0.5 mm, then cemented with resin cement. Results: The mean fracture load for the glass ceramic was 431.8 ± 217.9 N, while for the porcelain, it was 454.4 ± 72.1 N. Failure modes differed considerably: porcelain showed more chipping, while lithium disilicate was associated with tooth structure failure. Conclusion: The material used did not significantly affect the fracture load of thin ceramic laminates in static tests. However, failure modes differed considerably. It was not possible to determine a set of mechanical cycling parameters that could establish the fatigue properties of thin ceramic laminates, as the maximum number of cycles reached was 536,818.

A two‐scale numerical analysis of intra‐yarn hybrid natural/synthetic woven composites

AbstractThis paper investigates how combining natural and synthetic fibers within yarns, altering the degree of hybridisation, and varying weave architectures affect the homogenized elastic properties and stress distributions in 2D woven composite laminae using a two‐scale homogenization scheme. The novelty lies in integrating a micro‐scale representative volume element model with a meso‐scale repeating unit cell model to capture intra‐yarn natural/synthetic fiber hybridisation. The study focuses on 2/2 twill and 5‐harness satin woven laminae with flax/E‐glass, hemp/E‐glass and basalt/E‐glass hybrid yarns, all with a total fiber volume fraction of 0.6. Fiber distributions are created through a random sequential expansion algorithm for hybrid RVEs, while periodic meso‐structures are used to define weave architectures for RUCs. Results show that yarn‐level fiber hybridisation significantly influences matrix stress distributions, with variations of up to 22%. In contrast, weave architecture has a minimal effect, with variations in homogenized properties below 2%. Varying fiber types, degrees of hybridisation and weave architectures allow for the tailoring of yarn and lamina properties and altering the stress distributions at micro‐ and meso‐scales and potentially influencing damage mechanisms. The modeling approach for analyzing the mechanical behavior of intra‐yarn hybrid natural/synthetic woven laminae could potentially be used to tailor their tolerance to damage.Highlights Two‐scale homogenization integrates RVE and RUC for 2D woven hybrid composites. Analyzed flax/E‐glass, hemp/E‐glass, basalt/E‐glass in twill and satin weaves. Intra‐yarn hybridisation significantly affects properties and stress fields. Hybridizing fibers offers tailored properties and may improve damage tolerance.

Influence of stacking sequence on the mechanical properties of banana-glass fiber hybrid laminates for automotive shells

The development of composite materials using natural fibers has garnered significant global research interest. Banana fibers, due to their abundant availability and rapid growth cycle, present a promising option for composite material development. When combined with synthetic fibers to form hybrid composites, the resulting material may exhibit significantly improved properties, which is desirable for automotive body manufacturing. The hybrid properties of such composites, however, remain largely unexplored and require thorough evaluation. This study investigates the mechanical performance of hybrid laminated composites fabricated from banana and woven glass fibers bonded with epoxy resin. The composites were produced using non-crimp banana (B) fiber and woven glass (WG) fiber fabrics through the hand lay-up process with four distinct stacking sequences: [WG/B-0⁰/B-0⁰/WG], [WG/B-0⁰/B-45⁰/WG], [WG/B-0⁰/B-60⁰/WG], and [WG/B-0⁰/B-90⁰/WG]. Comprehensive mechanical testing, including tensile, flexural, impact, and hardness tests, along with environmental testing (water diffusion) was conducted in accordance with ASTM standards. Results indicated that the [WG/B-0⁰/B-0⁰/WG] configuration exhibited the highest tensile strength, while the [WG/B-0⁰/B-60⁰/WG] configuration achieved superior flexural strength. The [WG/B-0⁰/B-45⁰/WG] configuration demonstrated the highest impact strength and energy absorption. Rockwell hardness testing revealed that the average hardness numbers for all orientations were approximately 79, which is considered moderate for composite materials. Water absorption tests showed maximum water saturation in [WG/B-0⁰/B-90⁰/WG] of ∼5.5 %, where the other laminates had water saturation between 4.5 and 4.9 %. The microscopic analysis of the [WG/B-0⁰/B-45⁰/WG] laminate suggests fiber-matrix debonding and fiber pull-out as the major cause of failure under tensile and flexural loading. These findings suggest that the hybrid laminated composites, particularly the [WG/B-0⁰/B-0⁰/WG] and [WG/B-0⁰/B-45⁰/WG] configurations, exhibit mechanical properties suitable for automotive body applications.

Effect of Cutting Methods on Magnetic Properties of Non-Oriented Silicon Steel Lamination

Effect of Cutting Methods on Magnetic Properties of Non-Oriented Silicon Steel Lamination

Mechanical properties and damage mechanism of SMAHC laminates

Abstract The combination of smart materials and composite materials to achieve lightweight and intelligent structures has been an important research direction in recent years. In this paper, a three-dimensional woven hybrid shape memory alloy (SMA actuator) is modularly implanted into a composite laminate to prepare a SMA hybrid composite (SMAHC) laminate. The orthogonal test was designed with the three variables of SMA actuator modular implantation position, SMA pre-strain and SMA number. According to the orthogonal test results and finite element results, the influence of the three variables on the stiffness before heating, the stiffness change rate after heating and the strength of SMAHC laminates was studied. According to the test index, the influence of the three variables on the results was further evaluated. The results show that the implantation position has the greatest influence on the mechanical properties of SMAHC laminates, followed by SMA pre-strain, and the number of SMA has the least influence. The location and form of damage of SMAHC laminates are further summarized, and the bending damage mechanism of SMAHC laminates is analyzed.

Analyses and control of interphase structures and adhesion properties of epoxy resin/epoxy resin for development of CFRP adhesion systems

In the adhesion of carbon fiber reinforced plastics (CFRP), the boundary regions were composed of only epoxy resins of CFRP matrix and adhesives, and their similar epoxy structures pose significant difficulty in studying the adhesion mechanism. Herein, we focused on structure and properties of laminates of epoxy resin substrates and adhesives with different curing conditions of substrates. We prepared laminates using deuterated epoxy adhesives or fluorinated epoxy adhesives, and their boundary regions were identified through confocal Raman scattering measurements. The regions were distributed into “penetration” and “interphase”. In particular, the penetration phase is a key of the adhesion properties. The penetration behaviors strongly depended on the crosslinking densities of the adherends, suggesting that the penetration regions would be directly impacted by the curing conditions of the substrates and molecular size of epoxy adhesive precursors. Our findings provide insights into novel designs of the reliable adhesion-based manufacturing systems of CFRP.

Ultraviolet cross‐linked ultra‐high molecular weight polyethylene fiber laminate: Preparation and mechanism analysis for its excellent mechanical properties

AbstractThe development of high‐performance ultra‐high molecular weight polyethylene (UHMWPE) fiber laminate is of great significance in the field of bulletproof materials. However, due to the poor heat resistance of UHMWPE fibers, it is challenging to achieve exceptional mechanical properties in laminates prepared via hot‐pressing. In this study, we employ a self‐made ultraviolet (UV) cross‐linked fully drawn yarn of UHMWPE (UVFDY), which exhibits excellent heat resistance, to prepare a UVFDY/unsaturated polyester resin (UPR) laminate through hot‐pressing. The laminate possesses outstanding mechanical properties, which includes high Barcol hardness (~40 HBa), high tensile strength (~800 MPa), and high storage modulus (~13.7 GPa at 25°C), surpassing those of most conventional UHMWPE fiber laminates. Its remarkable mechanical properties are primarily attributed to the highly cross‐linked networks of cured UPR and the stable structures (gel content ~89%, crystallinity ~81.5%, orientation ~93%, and smoother fiber surface) of UVFDY during hot‐pressing. This work not only provides valuable insights into the preparation of high‐performance UHMWPE fiber laminates but also promotes applications for the self‐made UV cross‐linked UHMWPE fiber.Highlights Novel laminate possesses high Barcol hardness. The tensile strength and storage modulus of novel laminate are excellent. UV irradiated fiber with high structural stability during hot‐pressing.

Finite element analysis on the compression and crush responses of laminates with unidirectionally arrayed chopped strand in 0° plies

AbstractThe outstanding mechanical performance and flowability of unidirectionally arrayed chopped strands laminates (UACS) give them an advantage in the manufacture of engineering structures with complex geometries. In this research, the mechanical response of UACS laminates with bi‐angled slits and staggered slits under quasi‐static compression and progressive crushing loads is numerically analyzed for the first time. The aim is to clarify the damage mechanism of UACS laminates under compressive and crushing load. Simulation results reveal that the compressive strength of [90/0]4s UACS laminates with bi‐angled slits is 635.9 MPa, with an error of 4.2% compared to experimental data. For the stacking sequence of [0/90]4s, the strength is measured as 581.96 MPa with a 5% error. Proposed finite element model could accurately describe the mechanical properties of UACS laminates. Additionally, the progressive crushing response is in good agreement with the experimental data, the error in energy absorption for [90/0]4s UACS laminates with bi‐angled slits is noted at 7% compared to experimental values. It has been demonstrated that bi‐angled slits significantly contribute in restraining the propagation of delamination and improving the amount of energy absorption of UACS laminates.Highlights The mechanical response of UACS laminates under compressive and progressive crushing load was numerically analyzed. The compressive damage propagation of UACS laminates with different slit patterns in 0° layer was demonstrated. The effect of different slit patterns on inhibiting delamination propagation and increasing energy absorption of UACS laminates under progressive crushing load was numerically analyzed.

Prediction of mechanical property of open-hole composite laminates using generalized regression neural network method

Prediction of mechanical property of open-hole composite laminates using generalized regression neural network method

Atomic force microscopy-based nanoindentation technique for characterizing the transverse and shear moduli of flax fibers

Experimentally evaluating the elastic properties of flax fibers is challenging due to their complex hierarchical structure, and a standard test procedure for measuring their transverse and shear moduli is currently not reported in the literature. Hence, this study presents an atomic force microscopy (AFM) based nanoindentation technique to evaluate the transverse and shear moduli of flax fiber. A high-precision focused ion beam (FIB)-milling process was used to fabricate a flat surface for indentation along the longitudinal fiber cross-section of the fiber and transverse fiber cross-section by polishing the unidirectional (UD) lamina in order to evaluate the indentation modulus. Further, Swanson's numerical contour approach was adopted to evaluate the elastic properties of the fiber from the measured indentation modulus. The accuracy of the experimentally obtained fiber properties is verified by using it in a micromechanics model for predicting the elastic properties of the UD lamina and comparing it with experimental results reported in the literature.

Experimental and multi-scale modeling research on the dynamic tensile properties of open-hole CFRP laminates subjected to strain rates of low to medium

Experimental and multi-scale modeling research on the dynamic tensile properties of open-hole CFRP laminates subjected to strain rates of low to medium

Mechanical characteristics of kenaf-glass fiber reinforced hybrid composites by varying the stacking sequences

Fiber composite materials are preferred for their lightweight, low-cost, and commercial uses. As part of this study, laminate materials consisting of two different fiber materials as their reinforcement materials are produced using the hand layup method. This study investigates the mechanical properties of hybrid composite laminates fabricated using kenaf and glass fibers. Six stacking arrangements of the fibers are examined, alongside two reference laminates with individual reinforcements. Epoxy resins HY951 and LY556 serve as matrix materials. ASTM standards guide the mechanical testing of the composites. Results indicate varied tensile strengths based on stacking sequence, with laminate L2 (KKGKK) featuring a single glass fiber core at 75 MPa, and increasing strengths in laminates with additional glass layers: L1 (GKKKG) at 123 MPa, L5 (KGKGK) at 110 MPa, L3 (GKGKG) at 150 MPa, L6 (KGGGK) at 118 MPa, and L4 (GGKGG) at 159 MPa, the highest among all. It was observed that adding one layer of glass fiber with kenaf fiber boosts strength and modulus by 9.52% and 12.19% respectively, compared to pure kenaf fiber composites. Morphological analysis via Scanning Electron Microscopy (SEM) confirms failure due to initial crack propagation in the matrix and fibers. This study offers insights into hybrid composite laminate behavior, pertinent for various industrial applications.

Prediction of temperature and structural properties of fibre-reinforced polymer laminates under simulated fire exposure using artificial neural networks

Load-bearing fibre reinforced polymer laminates soften and decompose when exposed to high temperature fire which may cause significant deformation and weakening, ultimately leading to failure. A combined experimental and modelling study is presented to predict the fire structural survivability of laminates using artificial neural networks based on machine learning. Multiple experimental fire-under-tension load tests are performed under identical conditions to determine the average values and scatter to the surface temperatures, deformation rates and rupture times for an E-glass/vinyl ester laminate. A data-driven modelling strategy based on artificial neural networks is presented that can predict the temperatures and fire structural properties for the laminate when subject to combined fire exposure and tension loading. It is shown that the model gives excellent agreement to the measured surface temperatures, deformations, and time-to-failure of the laminate when exposed to one-sided heating at a constant heat flux. It is envisioned that the ANN based model could be used to assess the fire structural survivability of load-bearing composite structures exposed to fire.

Shape memory sandwich structure with reprogrammable shape and mechanical properties

Sandwich structures are usually used in aerospace and automotive engineering fields. By selecting different core materials and panels, a large number of design strategies are proposed to obtain various types of sandwich structures for various applications. Here, we developed a kind of shape memory sandwich structure using shape memory foam and laminates. The sandwich structure can not only program its shape utilizing SME but also can adjust its mechanical properties by controlling its temperature or shape. The mechanical and thermal–mechanical properties of shape memory laminates, foam and sandwich structure were characterized, respectively. The energy absorption property and bending resistance of the shape memory sandwich structure after being programmed were studied by compression test and drop weight impact test. Shape programmable and mechanical properties adjustable suggest potential applications of this sandwich structure in an adjustable shock-absorbing interface and space deployable structure.