Composites Part C Open Access最新文献

This work explores the feasibility of adopting an LSI produced C/SiC composite to build an aeronautical Auxiliary Power Unit system muffler. The study first covers the experimental material characterization through tensile and compressive tests. The material properties are characterized also after exposing the samples to an oxidizing atmosphere, that is typical for the proposed application. The material response is characterized by significant non-linearities and a pseudo plastic response, which were numerically modeled using a Drucker-Prager model. The detailed design of the muffler is described and verified, for different loading conditions, using a Finite Element model. Finally, a full-scale prototype is produced and assembled, thus proving the technological feasibility of the design. The manufacturing phase required to study and understand the phenomena that were leading to defects in the proposed closed axial symmetric shape, and to implement suitable technological solutions in order to get an acceptable prototype.

This work explores a type of composite called thermoplastic polymer-fiber-reinforced polymers (PFRPs), often referred to as self-reinforced composites (SRCs). A representative PFRP was exemplified using unidirectional (UD) ultra-high-molecular-weight polyethylene (UHMWPE) fibers embedded in a high-density polyethylene (HDPE) matrix. The effects of compression molding temperature and pressure on the mechanical and morphological behaviors of the filament-wound PFRPs with various fiber volume fractions ($V_f$) were experimentally investigated.

The results elucidate the evolution of morphologies and tensile properties of the PFRPs due to thermal melting, fiber misalignment from pressure, and $V_f$-induced structural variance, which has not been comprehensively reported yet. The highest specific tensile strength and modulus of the PFRP laminae reach 600 MPa/(g/cm³) and 31 GPa/(g/cm³), respectively. These properties are comparable to glass-/aramid-fiber-reinforced polymers (GFRPs, GFRTPs, AFRPs, and AFRTPs), with PFRPs exhibiting better ductility (specific strain at peak load $\approx$ 4%/(g/cm³)) than other common polymer composites.

The motivation for this work was the high recyclability of PFRPs, which can be recycled by melting both the fibers and the matrix, and then reshaped them for re-manufacturing composites to maximize the efficiency in material reuse. This process simplifies the implementation of closed-loop recycling, re-manufacturing, and reuse to support sustainability in composites. This work aims to contribute to advancing thermoplastic PFRPs for their potential applications in various industries.

Natural fibre composites (NFCs) are not durable in the long run because of the susceptibility of natural fibres to environmental conditions and specifically moisture. Hybridizing NFC laminates externally, with synthetic fibre reinforcements, may improve durability, due to their inherent environmental resistance. This work aims to investigate the effects of glass hybridization, on flax fibre composites, studied via accelerated ageing. In specific, the durability of hybrid flax/glass fibre reinforced polymer composites, with two recyclable polymer matrices was investigated. Unidirectional (UD) flax and UD glass fibre reinforcements were employed to fabricate laminates, with two fully-recyclable off-the-shelf resin systems, as matrix: (i) a bio-based epoxy resin and (ii) an acrylic liquid thermoplastic (Elium®). In addition, a standard petroleum-based epoxy polymer matrix was for reference purposes. Weathering and hygrothermal ageing were used to test the durability of coupons, exposed to UV radiation/condensation/water spray environment (weathering ageing), and full-immersion in distilled water at 23, 40, and 60°C (hygrothermal ageing). In all cases, ageing was performed for a total duration of 56 days. The performance of the unaged and aged composite coupons was assessed and compared in terms of flexural and viscoelastic performance as well as SEM (Scanning Electron Microscopy) analysis. It was revealed that the addition of glass fibres with flax fibres in the hybrid composites improves the performance and better resistance against ageing environments than their neat flax fibre composites.

The aim of this study is to explore the use of sustainable basalt fiber (BF) as compared to glass fiber and talc in injection molded engineering polyamide 6,6 (PA 6,6) plastic composite. Basalt fibers having lengths of 3 mm and 12 mm were added to PA 6,6 at 23 and 30 wt.% to fabricate the composites. The addition of basalt fiber restricts the mobility of the polymer chain in the composites, leading to its increased viscosity. Rheological results showed that the out-of-phase response to the applied stress indicated that the 3 mm basalt fiber composite could dissipate more energy, and the elastic behaviour of the composite under deformation increased with increasing basalt fiber wt.%. The fiber length had a larger effect on the mechanical properties of the composites as compared to the fiber load. The 12 mm basalt fiber composites at 23 wt.% and 30 wt.% produced higher tensile strength and modulus than the 3 mm basalt fiber composites while the 3 mm basalt fiber composite at 30 wt.% resulted in a 25 % increase in flexural strength. The experimental and the theoretical modulus predicted by the rule of mixtures showed an interaction between the matrix and the basalt fiber. Morphological analysis shows more agglomeration in composites with 3 mm fiber than the 12 mm. Glass fiber-reinforced PA 6,6 showed slightly higher performance than basalt fiber-reinforced PA 6,6. However, the basalt fiber-reinforced composites demonstrated better performance in tensile strength, flexural modulus, flexural strength, and heat deflection temperature than talc-reinforced composites.

The research focus has shifted towards lightweight structures with high energy absorption capabilities due to advancements in automotive safety technology. This study specifically investigates the impact of cross-sectional area on the energy absorption characteristics of hemispherical composite shells. The experimental phase involves characterizing a glass fiber epoxy composite, followed by the manufacture of hemispherical composite shell specimens with varying cross-sectional areas. These specimens undergo quasi-static axial compressive loading, and the energy absorption parameters are analyzed. The results indicate a significant influence of the composite cross-sectional area on the crushing behavior of hemispherical shells, with a observed decrease in specific energy absorption as the cross-sectional area increases. Additionally, a 3D Finite Element (FE) model is created using ABAQUS FE code to numerically simulate the crushing process. The model’s predictions are compared and validated against experimentally measured values, demonstrating a satisfactory correlation.

In this study, an analytical and numerical analysis of a hybrid sandwich structure with a lattice core produced by additive manufacturing with composite facesheets is carried out. This paper aims to analytically calculate the mechanical behavior of the hybrid sandwich structure under three-point bending and to verify the results by the finite element method. The analytical method used in this article for the analysis of the composite sandwich structure is the First-Order Shear Deformation Theory (FSDT). The numerical analysis of the hybrid sandwich structure was performed in ANSYS. In the analyses, homogenized models of lattice structures, which had been previously validated, were employed to reduce the number of elements and thereby save time during the solution process. As a result of the study, an extensive investigation into the deformation, shear, and normal stress values of sandwich structures with lattice cores of varying aspect ratios has been carried out. The findings suggest a potential for optimization in lightweight structures, which could lead to innovative advancements in design and manufacturing processes within the aerospace and automotive sectors.

Bacterial wound infections are prevalent in daily life. However, conventional tissue adhesives lack antimicrobial properties. In this study, a redox method was employed to prepare a nano-silver solution with tannic acid as a dispersant. Subsequently, the nano-silver solution was combined with the precursor solution of the hydroxyethyl methacrylate/vinylpyrrolidone (HEMA/NVP) hydrogel. Finally, it was put under ultraviolet light to produce the hydrogel. The hydrogel exhibits remarkable extendibility (1223 %), an elastic modulus compatible with human skin tissue (3.7 ± 0.5 kPa), the strong adhesion to porcine skin tissue (24.67 ± 1.15 kPa) markedly exceeds that achieved by clinically utilized fibrin glue, low swelling ratio (75 ± 1.55 %), and demonstrates good in vitro antimicrobial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, it displays excellent biocompatibility with fibroblast cells (NIH/3T3) with cell viability above 80 %, favorable blood compatibility with goat blood, and moderate coagulation ability. It provides more possibilities for clinical wound repair.

Carbon fibre reinforced polymer (CFRP) laminates are used in various studies as Li-ion polymer (LiPo) battery packaging. However, their suitability as a packaging material is not well understood. The present study investigates the liquid absorption (water and lithium bis(trifluoromethanesulfonic)imide (LiTFSI) electrolyte immersion tests) and barrier layer properties (water vapour transmission rate (WVTR) and oxygen transmission rate (OTR) tests) of a 200 gsm woven CFRP laminate to assess its suitability as a battery packaging material. This is the first study to show that prolonged immersion in battery electrolyte does not change the mechanical properties of a woven CFRP laminate. Hence, the CFRP laminate may be suitable for structural battery components, such as current collectors and electrodes. However, CFRP should not be used as battery packaging, as OTR and WVTR values of the CFRP laminate were found to be five and one order of magnitudes higher than typical battery pouch materials (i.e. aluminium foil), respectively.

In this study, undulations and their influence on the longitudinal compressive strength of a unidirectional glass fiber reinforced polymer (GFRP) composite are investigated theoretically and experimentally. The objective of this research is to explore the failure mechanisms in FRP and to characterize the mechanical properties of FRP as a function of fiber orientation. For this purpose, a multiscale material model is developed that considers a stochastic fiber orientation distribution (FOD) and models matrix fracture-initiated failure. The relationship between compressive strength and undulation is investigated experimentally on standardized specimens made of unidirectional GFRP. The fiber orientations are measured using X-ray computed tomography and ImageJ image analysis, resulting in a binormal distribution of fiber orientations in the series of samples tested. To examine the failure process in detail, the compression tests are simulated using finite element analysis (FEA). Both the FEA results and the measured compressive strengths confirm the model assumption of matrix fracture-initiated failure under longitudinal compressive loading. The presented analytical model realistically represents the correlation of compressive strength with the FOD.

An experimental method was developed to examine the dynamic compression properties of structured polyurethane composites used as press belts within a shoe press of a paper machine. The objective was to investigate the influences of the geometrical surface structure and the matrix material composition on the compression properties. Two polyurethane formulations were tested under varying specimen conditions. The results show that the dynamic compression modulus increases with the applied load rate and that temperature and water saturation reduce the influence of dynamic effects on the compression modulus. Furthermore, it was observed that modifications of the matrix material have a more significant impact on the dynamic compression modulus than adaptions in the geometrical structure. This is addressed to the relatively small variations in possible surface designs. Finally, a rate-sensitivity index is introduced to quantify the tested specimens’ rate-sensitive behaviour.