Composites Part C Open Access最新文献

Hybrid composites armors made of closed-cell aluminum foam are developed for intended use in ballistic protective plates. The manufacturing process involved impregnation of shear thickening containing different micro and nano-fillers into aluminum foam panels which are subsequently bonded two AA 5086-H32 aluminum sheets that surrounded the targets, by using compression molding techniques. The effects of the addition of different nano-fillers as colloidal silica, gamma alumina, silica carbide, and Kevlar micro-fibers to the aluminum foam plates on the ballistic response of the hybrid composites armors were investigated. Scanning electron micrographs were used to investigate the interfacial interaction between specimen layers, and the influence of the nanoparticles impregnated within closed aluminum foam cells before and after high-velocity impacts. The ballistic impact resistance of the produced hybrid composite cell aluminum foam laminates was tested according to NATO standards using a semiautomatic 9 mm Beretta Cx4 Storm Rifle Luger. The results indicated that the performance of the hybrid composite armors made of aluminum foam were enhanced by the deposition of micro and nano-fillers into the surface of the closed-cell aluminum foam.Therefore, the ballistic impact resistance and energy absorption of the specimens were improved. The highest impact energy absorption capacity was achieved by the deposition of Kevlar micro-fibers, but the resulting plates have the highest target weight and thickness. Silica carbide powder followed by gamma alumina, and colloidal silica powder in that order, enhanced the impact energy absorption capability with the least target weight and thickness average. These findings indicate that introduction of micro and nano-fillers coating on closed-cell aluminum foam, improved a range from 4.9 to 30.9 J in comparison with untreated samples, therefore, it could be a promising method for strengthening interfacial bonding between layers of the aluminum foam composites.

Body armor is an indispensable material in the military and defense. The development of body armor nowadays has shifted to lower-cost material with comparable ballistic properties. This research studied the potential of sansevieria trifasciata (ST) fiber as a reinforcement in soft body armor composite. The ST fiber was treated with various NaOH concentrations to achieve the highest tensile strength. The result showed that the highest ST fiber strength was achieved at 1.2GPa by treating the fiber with 1 wt% NaOH solution. The rebound resilience properties of the natural rubber (NR) matrix were optimized by varying the accelerator and carbon black content and were tested according to ISO 4662. The optimum energy absorption of the NR matrix was obtained using 0.4 part per hundred rubber (phr) accelerator and 30 phr carbon black. The ballistic performance of ST/NR composites was evaluated through a simulation using LS-DYNA software. The ballistic simulation revealed that the minimum thickness of ST/NR composite was 15mm to stop a bullet with a velocity of 436m/s. The results of this study indicated that ST/NR green composite was a promising candidate for a soft body armor application.

In order to realize the engineering application of automated fiber placement for composite laminates, a method of the variable angle fiber placement was proposed to design the tube structures of variable stiffness composites based on the quadratic Bezier curve. The axial crushing responses were simulated to investigate the energy absorption characteristics of composite tubes. The results showed that the method of the variable angle fiber placement contributed to the improvement of the energy absorption effects. The maximum crushing force efficiency of the variable stiffness composite thin-walled tubes designed by the method was 49.04% which was 106.48% higher than the constant stiffness composite tube. The results could be helpful for the process of automated fiber placement and the design of the energy absorption for composite thin-walled structures.

Nylon/polyamide (PA6) is a major cause of ocean plastic pollution because of its extended use in commercial fishing activities. Recovery of this nylon from oceans and its use in manufacturing new materials or composites is urgently required to promote sustainability and circularity. In this work, unlike higher-density mineral fillers, lignin from the forestry industry was converted into biocarbon, which was used as a lightweight filler to manufacture recycled-ocean nylon (RN)-based composites. Biocarbon is a highly stable, competitive, and sustainable filler for high-performance engineering plastics such as nylon. Lignin was pyrolyzed at 600 °C followed by further treatment at 1200 °C (with and without cobalt (II) nitrate catalyst) to induce graphitization in the produced biocarbon. Among the three types of biocarbon samples, such as pyrolyzed at 600 °C, 1200 °C and 1200 °C catalyzed lignin biocarbon, the catalyzed biocarbon showed the maximum electrical conductivity. Catalyzed lignin biocarbon pyrolyzed at 1200 °C showed an increase of 85% in electrical conductivity compared to commercial mineral graphite. The biocomposites consisting of 600 °C biocarbon were manufactured by injection molding at different filler contents up to 40 wt.%. The biocomposites consisting of 40% of pyrolyzed lignin at 600 °C showed increased flexural strength, flexural modulus, and heat deflection temperature by 41, 76 and 76%, respectively, compared to neat RN. Improved properties of the prepared biocarbons and biocomposites showed the potential of RN-based composites in the automotive industries.

Contact formation and autohesion with respect to their role as the major mechanisms governing the tack between thermoset prepregs in automated fiber placement were explored. Therefore, a novel 90° peel test with strictly separated and individually controllable compaction and debonding phases was employed for experimental tack characterization in a rheometer. Variation of compaction pressure, dwell time and temperature enabled the experimental isolation of contact formation and autohesion influences. The experimentally determined tack, ply-ply contact area and resin viscoelastic characteristics were used to parametrize simplified semi-empirical bond strength sub-models that have originally been developed for thermoplastic composite manufacturing techniques. The model prediction was validated successfully within the experimentally reproducible parameter range. Eventually, manufacturing scenarios for thermoset automated fiber placement (AFP) respecting different lay-up velocities (up to 1 m s⁻¹), compaction pressures (up to 10 N mm⁻²) and both lay-up and mold temperatures (20–60 °C) were assessed in terms of estimated prepreg tack. The implication of both mechanisms, contact formation and autohesion, in the evolution of prepreg tackiness was found to be able to replicate the bell-shaped tack curves proposed by the adhesion-cohesion balance.

Carbon fiber reinforced polymer composites (CFRPC) are commonly used in various applications like sports, aviation, transportation, and the building sector. In particular, CFRPC preparations (intermediate products) are employed in CFRPC manufacturing, with much waste being generated through fabrications procedures and after its life cycle. Recovering of the carbon fiber from the waste of the CFRPC is a serious challenge for the renewable energy division. This paper describes an advances in the different recycling techniques of the recycled carbon fiber from the carbon fiber polymer composites and re-manufacturing of the recovered carbon fiber from the recycling technique into three-dimensional printed composite products. Physical and mechanical properties of the recovered carbon fiber printed using the different polymers matrix materials have been discussed. The aim of this paper also includes present problems and developments in the disposal and reuse of fiber-reinforced composites. Overall, the research presented in this paper gives valuable insights into the recycling techniques of carbon fiber and remanufacturing of the recovered carbon fiber for society's long-term development. After a thorough review of the available literature, study gaps are identified in order to determine future paths in this work.

Epoxy R-Glass Fiber-Reinforced Polymer (GFRP) composite plates were hydrothermally aged at 60 °C for 23, 75, and 133 days. The water content reached 0.97 wt%, 1.45 wt% and 1.63 wt%, respectively. The studied GFRP matrix was inert to hydrolysis or chain scission, allowing for investigation of irreversible changes in the fiber-matrix interphase due to hydrothermal aging upon re-drying. During each period, a subset of the specimens was removed from the water bath and dried in a chamber. The weight loss upon drying was explained with epoxy leaching (impurities), sizing-rich interphase hydrolysis, glass fiber surface hydrolysis, accumulated degradation products escaping, and water changing state from bound to free. The influence of hydrothermal aging on the fiber-matrix interfacial properties was investigated. Lower interfacial strength of hydrothermally aged (wet) samples was attributed to plasticization of the epoxy, plasticization and degradation of the sizing-rich interphase (including formation of hydrolytic flaws), and hydrolytic degradation of the glass fiber surface. The kinetics of epoxy-compatible epoxysilane W2020 sizing-rich interphase hydrolysis provided an estimate of ca. 1.49%, 4.80%, and 8.49% of the total composite interphase degraded after 23, 75, and 133 days, respectively. At these conditions, the interface lost 39%, 48%, and 51% of its strength. Upon re-drying the specimens, a significant part of the interfacial strength was regained. Furthermore, an upward trend was observed, being 13%, 10% and 3% strength, respectively; thus, indicating a possibility of partial recovery of properties.

Sustainable hybrid fillers including biocarbon (BioC) and recycled carbon fibers (rCF) are used to reinforce the polyphenylene sulfide (PPS). The PPS biocomposites were compared with the conventional talc filled counterparts. The PPS/BioC/rCF biocomposites have comparable specific mechanical properties and thermal stability to the PPS/talc/rCF composites. However, the former has higher content of sustainable fillers, which provides better energy saving and emission reduction properties. The biocomposites filled with BioC/rCF showed a similar degradation process as talc/rCF counterparts during the heat aging process. This study can help open high-end application options (e.g. Electric Vehicle (EV) parts) of PPS composites reinforced by sustainable carbon fillers.

In this paper, electrodeposition was successfully used to prepare a kind of polyester fiber flexible broadband shielding material based on PET fabric. The Ni-Fe alloy coating prepared by electrodeposition can completely and evenly cover the substrate. The maximum saturation magnetic moment was 93.16 emu/g. The sample with the highest permeability was prepared through the process exploration experiment. The permeability increases first and then decreases with the increase of Fe content in the coating. The phase with the highest permeability in the coating is Ni₃Fe. The simulation results show that the shielding effect of Ni-Fe/Cu layer was better than that of Cu/Ni-Fe layers. The optimal shielding effectiveness can reach 28.4db in 10 kHz magnetic field and 80 dB in 100k∼10 MHz magnetic field. In the electromagnetic field of 30M∼18 GHz, the shielding effectiveness is greater than 85 dB, up to 110 dB. The tensile strength of the shielding fabric is 91.63 MPa, the displacement is small, and the material has no obvious elasticity. During the stretching process, the coating breaks first, and then the PET fabric breaks.

Adhesive bonding is extensively used by commanding industries such as automotive and aircraft sectors. Nevertheless, due to the intricate mechanical behaviour of adhesively bonded joints, especially when crack propagation occurs at the adhesive layer, improvement of new numerical techniques to simulate this bonding approach is currently under development. In this work, a recent crack propagation algorithm based on a meshless technique is implemented to analyse mode II fracture propagation in adhesively bonded joints. After the problem domain is discretized with an independent set of field nodes, a background numerical integration mesh is constructed. The crack tip advancement is then simulated by iteratively rearranging the field nodes and integration cells at the crack tip. Radial point interpolation (RPI) functions are constructed using the concept of influence domains, allowing to obtain sparse and stable global matrices. To assess the suitability of the proposed method, End-notched flexure (ENF) specimens were manufactured and tested. The numerical simulation justly reproduces the experimental data provided and, thus, the numerical model can be applied to mode-II shear loadings and industrial applications for design purposes.