In this study, a novel multiscale model based on the finite-volume direct averaging micromechanics (FVDAM) theory and molecular dynamics (MD) was developed to predict the interfacial cyclic debonding behaviour of composites. At the microscale, a solid interface with accumulated damage was incorporated using FVDAM, which enabled the simulation of both localised and homogenised interfacial damage responses under cyclic loading; a significant reduction in strength was observed after 10 loading cycles, implying the interfacial damage accumulation. At the atomic-scale, an interface model was built and subjected to cyclic loadings using MD simulation; the stress peak after 5 cycles was approximately half of the initial value, which provides damage parameters for upper-scale calculations and reveals the fundamental mechanism of interfacial cyclic debonding. The experimental data of unidirectional SCS-6/Ti-15-3 composites under cyclic loading were adopted to verify the proposed model. Furthermore, the influence of thermal residual stress and fibre orientation was investigated, which offers valuable insights for composite design and manufacturing.
Composites Part A: Applied Science and Manufacturing
Reactive Extrusion Additive Manufacturing of a Short Carbon Fiber Thermosetting Composite via Active Mixing
Pratik Koirala, Robert Pavlovic, Athena Aber, Michael J. Fogg, Cole Mensch, Carolyn C. Seepersad, Mehran Tehrani
doi:10.1016/j.compositesa.2023.107989
通过活性混合实现短碳纤维热固性复合材料的反应挤出增材制造
Reactive extrusion additive manufacturing (REAM) is a recently developed process that utilizes reactive thermoset resin-hardener systems that are mixed inside a shearing element, deposited layer by layer to form a structure, and cured in-situ without external energy. An externally powered active mixing element was developed and used to demonstrate REAM with a highly viscous resin that was filled with 10 wt.% chopped carbon fibers. This was achieved by adding fumed silica and increasing the temperature of the fiber-resin mixture to enable effective in-situ mixing while maintaining shape retention upon deposition. Tensile properties of fiber-reinforced and reference REAM parts were measured and explained using their fiber alignment and length distribution. Finally, a mechanics model was utilized to determine the optimal short fiber content for strength and stiffness, considering the degradation of fiber length at higher volume fractions due to the mixing.
Converting bio-waste rice into ultralight hierarchical porous carbon to pack polyethylene glycol for multifunctional applications:Experiment and molecular dynamics simulations
Pei Li, Daili Feng, Yanhui Feng, Xinxin Zhang
doi:10.1016/j.compositesa.2023.107979
将生物废料稻米转化为超轻分层多孔碳，以封装聚乙二醇，实现多功能应用：实验与分子动力学模拟
A structural-functional integrated shape-stabilized composite phase change material (PCM) was synthesized by converting biowaste rice into ultralight (0.08 g/cm3) hierarchical porous carbon (CNR) to pack polyethylene glycol (PEG) PCM. The thermal property and corresponding mechanism were analyzed. The results show that the composite PCM exhibits excellent thermal storage efficiency (93.3%), considerable solar photothermal conversion efficiency and superior thermal stability. The interfacial thermal resistance (ITR) of PEG/CNR is 73% lower than graphene foam-based composite PCM thus a fast transient temperature response. Particularly, the package of PEG endowed composite PCM with elastic characteristic thereby an enhanced compressive strength. Furthermore, covering PEG/CNR results in a delay of approximately 1.3 times in reaching the peak temperature on the surface of electronic components, and a delay of 5 times in cooling time. This study presents solid guidelines for societal development that is sustainable and makes some recommendations for construction of composite PCMs combining multifunctional applications.
Interfacial engineering of hybrid MXene-Ni-CF tri-core-shell composites for electromagnetic interference shielding and E-heating applications
Yi Hu, Guoyu Yang, Junzhen Chen, Yujun Li, Ming Dong, Han Zhang, Emiliano Bilotti, Jianjun Jiang, Dimitrios G. Papageorgiou
doi:10.1016/j.compositesa.2023.107990
用于电磁干扰屏蔽和电加热应用的混合 MXene-Ni-CF 三核壳复合材料的界面工程设计
In response to the the needs for multifunctional carbon fiber reinforced polymer (CFRP) composites, we present a novel, tri-core-shell CFRP consisting of MXene, nickel (Ni), and CF synthesized throughlayer-by-layer assembly. The hybridcomposites demonstrate remarkable electrical conductivity and electromagnetic interference (EMI) shielding, alongside efficient electrical (E-) heating properties. Additionally, the MXene-Ni-CF/EP hybrid composite displayed improved flexural strength and ILSS compared to Ni-CF/EP composite. Outstanding enhancements were observed in both the through-thickness and in-plane electrical conductivities, with a 116-fold and 14-fold improvement, respectively, attributed to the complex MXene-Ni-CF conductive paths. The hierarchical compositessignificantly outperformed the state of the art and demonstrated a superior EMI shielding efficiency of 72.4 dB by virtue of the dielectric and magnetic loss mechanisms. Thelow-voltage-driven E-heating capacity could be utilized for de-icing applications due to the thermally conductive networks. The producedcomposites offer a highly promising solution to tackle challenges associated with lightning strikes and icy weather conditions, while also aligning with the goal of cost-effective industrial production.
Economic and environmental challenges are driving development towards more efficient and lighter materials. Polyethylene (PE) and polyamide (PA6) are among the most used polymers and their assembly in multilayer make them efficient protective materials. The aim of this work is to design new multilayer composite films based on polyethylene and polyamide with high barrier properties. A coextrusion process with layer multiplier elements (LME) made it possible to carry out 100 μm-thick multilayer films containing 5 up to 1025 layers. Loaded PE/PA6 multilayer films were made by incorporating Cloisite particles (organo-modified montmorillonite – C30B) at 5 wt% into the PA6 layers. For comparison PA6 films with and without fillers were also made by using the same coextrusion process. The structural and thermal properties of all multilayer films were correlated with the water and gas barrier properties. A good dispersion of exfoliated C30B in the PA6 phase was observed even for the thinnest confined layers of PA6 in PE/PA6 multilayers (∼90 nm). We showed the complexity of the multinanolayer structures involving interphases as well as the complexity of the transfer mechanisms. The serial model used for predicting permeability highlighted some significant improvements of the gas barrier properties of confined PA6 layers. The barrier effect on all the multilayer films was, however, limited due to the “on-edge” orientation of the crystalline phases and structural defects induced during the coextrusion process. Despite this, the confinement of nanofillers in PA6 multilayers and in PA6 layers of PE/PA6 multilayers allowed to increase the barrier properties of multilayers.
Cartilage tissue plays an important role in our life activities. The poor self-repair capacity makes cartilage tissue engineering an urgent clinical demand. Among them, the development of tissue engineering scaffolds with both biomimetic features and microenvironment signal sensing abilities could significantly promote the development of cartilage tissue engineering. While most of the reported cartilage scaffolds have no intelligent sensing features. Herein, a ternary composite 3D printing scaffold with both strain sensing ability and desired mechanical property was developed, by using regenerated silk fibroin (RSF) and polyacrylamide (PAM) as main matrixes, and oxidized bacterial cellulose nanofibers (OBC) as filler. Then, the mechanical property, strain sensing ability and corresponding ectopic chondrogenic activity of the RSF/PAM/OBC 3D printing scaffold were comprehensively investigated and verified through in vitro and in vivo studies. Results showed that the RSF/PAM/OBC (OBC-6.3 wt%) scaffold owns effective strain sensing property and desired ectopic chondrogenesis capabilities in the subcutaneous microenvironment. It could be used for reliable monitoring the joint movements, related motion amplitudes, and also promoting the cartilage specifical genes expression. These features not only confirmed the great potential of these smart scaffolds for applications in tissue reconstruction and mechanical stimulus monitoring of the corresponding tissue microenvironment, but also proved the possibility of employing various 3D printing scaffolds as flexible bioelectronics.
Energy release rate for steady-state fiber debonding in structural battery composites
Kai Guo, N. Sridhar, Choon Chiang Foo, Bharathi Madurai Srinivasan
doi:10.1016/j.compscitech.2023.110416
电池结构复合材料稳态纤维脱粘的能量释放率
Structural battery composites are multifunctional materials intended to provide energy storage capacity while maintaining their strength and load bearing capacity under significant mechanical loads. In this study, we investigate the mechanics of carbon fiber debonding, a critical failure mechanism in structural battery composites. The carbon fibers are intended to serve both as an electrochemically active material and to bear mechanical load in the composite system. We derive an analytical solution to the energy release rate for steady-state fiber debonding for different electrochemical and mechanical loading cases with the aid of the classical solution for the Eshelby inclusion problem. The analytical solutions are validated with finite element simulations. We find a higher energy release rate and thus a greater driving force for fiber debonding is caused either by a lower lithium concentration in the fiber and/or by greater transverse mechanical loads such as biaxial tension or shear applied at the far field in the matrix. We find that the model is predictive even for transversely isotropic fibers despite the assumption that the fiber is elastically isotropic in the model. This work can provide guidance for the design of mechanically robust structural batteries.
A three-dimensional failure criterion model considering the effects of fiber misalignment on longitudinal tensile failure
Naiyu Liu, Puhui Chen
doi:10.1016/j.compscitech.2023.110424
考虑纤维错位对纵向拉伸失效影响的三维失效准则模型
This paper proposes a three-dimensional failure criterion model for unidirectional fiber-reinforced composites. In contrast to previous models that only accounted for the effect of fiber misalignment in the presence of longitudinal compressive stress, the proposed failure criterion model comprehensively considers the effect of localized misaligned regions on the failure under any stress state. Another key contribution of this study is the introduction of the effective misalignment angle. Considering effective misalignment angles, the proposed failure criterion model can reasonably reveal the effect of localized misaligned regions on the failure behavior under different stress states. The agreement between the predicted results and the experimental data proves that the proposed model has good applicability. Furthermore, the influence of initial misalignment angles on failure is analyzed under varying stress conditions. The results indicate that even under longitudinal tensile stress, the initial misalignment angle still plays an important role in the failure behavior of materials.
Modelling the damage evolution in unidirectional all-carbon hybrid laminates
Amaury Ollic, Fariborz Sheibanian, Babak Fazlali, Yentl Swolfs, Stepan V. Lomov, Valter Carvelli
doi:10.1016/j.compscitech.2023.110420
单向全碳混合层压板损伤演变建模
Hybrid reinforcements for composites have been extensively studied and adopted to overcome the lack of ductility via pseudo-ductility. Thin-ply all-carbon interlayer hybrid laminates have attracted attention for their peculiar pseudo-ductile tensile response. At the same time, conventional thick plies have been barely considered. This work developed a finite element model to simulate the complex tensile damage scenario of unidirectional thin- and thick-ply all-carbon interlayer hybrid laminates. The damage modes intended in the numerical model were fragmentation in the low-elongation (LE) plies, and delamination of LE and high-elongation (HE) ply interfaces. Thin- and thick-ply hybrid laminates were modelled and compared to available experiments. The numerical model was also adopted to simulate different layups to predict the effect of LE thickness fraction on the pseudo-ductile tensile behaviour and the evolution of damage modes. As suggested in the literature, the results allowed us to depict the damage mode map of the considered hybrid laminates. The map distinguishes the all-carbon hybrid laminate configurations with pseudo-ductile and brittle tensile responses.
为了通过假韧性克服延展性不足的问题，人们对复合材料的混合增强材料进行了广泛的研究和采用。薄层全碳夹层混合层压板因其奇特的假延展拉伸响应而备受关注。与此同时，传统的厚层板几乎没有被考虑。本研究开发了一种有限元模型，用于模拟单向薄层和厚层全碳夹层混合层压板的复杂拉伸损伤情况。数值模型中的损伤模式为低伸长率（LE）层的碎裂以及 LE 和高伸长率（HE）层界面的分层。对薄层和厚层混合层压板进行了建模，并与现有实验进行了比较。数值模型还用于模拟不同的层叠结构，以预测 LE 厚度对伪韧性拉伸行为和损伤模式演变的影响。正如文献中建议的那样，研究结果使我们能够描绘出所考虑的混合层压板的损伤模式图。该图区分了具有假韧性和脆性拉伸响应的全碳混合层压板配置。
