今日更新：Composite Structures 6 篇，Composites Part A: Applied Science and Manufacturing 2 篇，Composites Part B: Engineering 1 篇，Composites Science and Technology 1 篇
Composite Structures
Envelope enrichment method for homogenization of non-periodic structures
Florian Vazeille, Louis Laberge Lebel
doi:10.1016/j.compstruct.2023.117819
非周期性结构均质化的包络富集法
The homogenization of composite materials is critical for accurately predicting their mechanical performance, particularly when complex reinforcement arrangements are involved. Microstructural characteristics exert a substantial influence on the composite’s properties during practical applications. A widely adopted approach for analyzing composites is the numerical simulation of a Representative Volume Element (RVE). Although this method is well-established for periodic RVEs, it encounters difficulties when applied to non-periodic meshes, which complicates the imposition of classical boundary conditions on nodes exhibiting varying properties. To address this challenge, we propose a novel methodology that involves modeling an envelope surrounding the RVE, to which periodic boundary conditions are applied. By defining the envelope as a homogeneous material, stress transmission to the RVE is facilitated. The stiffness tensor of the envelope is updated iteratively through a homogenization process, ultimately converging to the effective properties of the RVE. The method is validated on a non-periodic arrangement of spherical inclusions embedded within a matrix. Convergence is observed in the different cases studied within ten iterations and the results are found within the Voigt and Reuss bound.
Design-oriented Stress-strain Model for RC Columns with Dual FRP- Steel Confinement Mechanism
Javad Shayanfar, Joaquim A. O. Barros, Mohammadali Rezazadeh
doi:10.1016/j.compstruct.2023.117821
采用玻璃钢-钢双重约束机制的 RC 柱应力-应变模型的设计导向性
Many research studies have been conducted to evaluate confinement-induced enhancements on the mechanical properties of FRP (fiber-reinforced polymers)-confined plain concrete elements subjected to axial compressive loading, leading to the development of extensive predictive models. Nevertheless, experimental stress-strain results for FRP-confined RC columns (FCRC) have demonstrated some behavioural features that cannot be simulated accurately through this kind of model, developed exclusively for FRP-confined concrete columns (FCC). In this paper, a new design-oriented stress-strain model is proposed for the prediction of load-carrying capacity versus axial strain relationship of FCRC. For this purpose, a new parabolic stress-strain expression is developed for calculating the first branch of FCRC’s response up to the transition zone, followed by a linear function. New formulations are proposed to determine the first branch’s stress-strain gradient, transition zone-related information and the second branch’s slope, calibrated using a large test database of FCRC. The proposed design-oriented model is capable of simulating accurately the combined influence of the dual FRP and steel confinement on load-carrying capacity versus axial strain relationship of FCRC. Lastly, the capability of this model is validated by comparison to existing experimental data of FCRC and those obtained from some of existing models in the literature.
An enhanced constitutive model to predict plastic deformation and multiple failure mechanisms in fibre-reinforced polymer composite materials
I.R. Cózar, F. Otero, P. Maimí, E.V. González, A. Turon, P.P. Camanho
doi:10.1016/j.compstruct.2023.117696
预测纤维增强聚合物复合材料塑性变形和多重失效机制的增强构效模型
Spurious damage modes in continuum damage mechanics models for fiber-reinforced polymer composite materials based on the effective stress tensor can be generated when large strains occur. A methodology to prevent this spurious phenomenon is developed in the present work. The longitudinal damage activation functions are based on the effective stress tensor, however, nominal stresses are used on the transverse damage activation functions. The proposed method can be straightforwardly implemented on previously-developed constitutive models which use effective stress tensor, an explicit implementation of the proposed constitutive model is presented. The enhancement of the predicted failure mechanisms obtained from the present constitutive model, with respect to the models which use effective stress tensor, is demonstrated. The proposed constitutive model presents a good agreement of the predicted failure pattern obtained from open-hole compressive experimental tests, as well as on the predicted failure strength.
Mass lumping schemes fitted to MLS-based numerical manifold method in vibration of plates with cutouts using CPT and FSDT
Shuaixing Zhao, Shan Lin, Miao Dong, Hongwei Guo, Hong Zheng
doi:10.1016/j.compstruct.2023.117815
在使用 CPT 和 FSDT 的带切口的板振动中，基于 MLS 的数值流形方法适用的质量叠加方案
It is critical to accurately extract the natural frequencies in the transverse vibration of plates using the classical plate theory (CPT) and the first-order shear deformation plate theory (FSDT). The moving least squares (MLS) based numerical manifold method (MLS-based NMM) in conjunction with a suitable diagonally lumped mass matrix is a reasonable choice because it can naturally treat plates with cutouts and easily formulate an H2 regular approximation based on MLS interpolation, as well as mitigate shear locking issues for vibration analysis of thin plates based on FSDT. Moreover, the mass lumping techniques involving the row-sum method, the diagonal scaling method, and the mathematically rigorous manifold-based method are extended and derived in the unified framework of MLS-based NMM for transverse vibration analysis of plates. Furthermore, the positive-definiteness of the lumped mass matrix (LMM) generated by the manifold-based mass method is explained in MLS settings, and the row-sum method is proven to be a special case of the manifold-based method. A comprehensive comparative study of different LMMs is performed in accordance with the consistent mass matrix (CMM) on extensive numerical benchmarks. Numerical results demonstrate the convergence properties of LMMs compared with CMM in MLS-based NMM for plate vibration based on CPT and FSDT. It can be observed that LMMs yield comparable performance compared with CMM. The row-sum method obtains accurate results in most cases but can not guarantee the positivity. In contrast, the manifold method can guarantee the positive-definiteness of LMM and is more accurate than the diagonal scaling method in most cases.
Analysis and Experiments of Bi-stable Laminate Configuration Control Based on MFC Piezoelectric Actuation
Yulin Jiang, Lu Yang, Chaofeng Li, Xueyang Miao
doi:10.1016/j.compstruct.2023.117820
基于 MFC 压电致动的双稳态层压板配置控制分析与实验
This paper studies the configuration change control and the snap-through phenomenon of bi-stable laminate with the MFC piezoelectric plate. The kinetic and potential energy expressions of the piezoelectric bi-stable laminate were obtained based on the von-Karman hypothesis. The constitutive equations of the system were given using a six-parameter displacement model, and the potential function of the system was derived using Hamilton’s principle. The configuration changes of the piezoelectric bi-stable laminate under different geometrical conditions were analyzed. The influence of voltage on the bi-stable laminate configuration was studied by applying different driving voltages. The snap-through energy variation of the piezoelectric bi-stable laminate under different geometrical conditions was investigated. In the experimental part, the changes in bi-stable laminate configuration with different geometrical conditions and after attaching the piezoelectric plate were compared. Different driving voltages were applied to measure the difference in piezoelectric bi-stable laminate configuration, and the critical snap-through voltages were recorded. The measured changes in bi-stable laminate configuration and snap-through voltage at different voltages prove the correctness of the theoretical presentation.
Comprehensive 3-D homogenization approach for predicting mechanical properties and creep behavior of polymer nanocomposites reinforced with graphene nanoplatelets
Hadi Mehdipour, Abbas Rohani Bastami, Mohammad Hossein Soorgee
doi:10.1016/j.compstruct.2023.117823
预测石墨烯纳米片增强聚合物纳米复合材料力学性能和蠕变行为的综合三维均质化方法
The aim of this study is to provide a comprehensive 3-D homogenization approach based on the high-fidelity generalized method of cells method to predict the mechanical properties and creep behavior of polymer nanocomposite reinforced with graphene nanoplatelets. Several fundamental experimental aspects including the volume fraction, size, and random orientation of graphene nanoplatelets, the interphase region, and the aggregation state of nanofillers of graphene are taken into account. The present study introduces two novel perspectives. At first, the aggregation of graphene nanoplatelets is formulated as dependent on volume fraction. Then the size of graphene is formulated as an important factor affecting the interphase region and the mechanical properties of polymer nanocomposite. Micromechanical tests conducted using the proposed method illustrate the good agreement with experimental data. The results of the parametric study on different experimental aspects revealed important findings. (i) For a specific value of graphene nanoplatelet volume fraction, the mechanical properties of polymer nanocomposite are at the best state. By increasing the graphene content beyond the specified graphene content value, the effective properties of graphene are decreased. (ii) The size of graphene nanoplatelets and the characteristics of the graphene/polymer interphase region have a direct effect on the properties of the nanocomposite.
Composites Part A: Applied Science and Manufacturing
Rationally Designed Conductive Wood with Mechanoresponsive Electrical Resistance
Gabriella G. Mastantuoni, Van Chinh Tran, Jonas Garemark, Christopher H. Dreimol, Isak Engquist, Lars A. Berglund, Qi Zhou
doi:10.1016/j.compositesa.2023.107970
合理设计具有机动力电阻的导电木材
Porous cellular foams, combining lightweight, high strength, and compressibility, hold great promise in a wide range of advanced applications. Here, the native structure of pine wood was modified by in-situ lignin sulfonation and unidirectional freezing, resulting in an alveolate structure inside the wood cell wall with arrays of sub-100 nm channels. The obtained wood foam exhibited highly enhanced permeability while retaining the native cellular arrangement and high lignin and hemicellulose content. Such engineered cellular foam contributed to superior mechanical performance with compressive strength of 9 MPa and Young’s modulus of 344 MPa in the longitudinal direction. The high porosity allowed homogeneous infiltration of conductive polymer PEDOT:PSS inside the wood cell wall. The resulting composite exhibited high conductivity, sponge-like compressibility and the ability to modulate electrical resistance in a reversible manner in the radial direction. This rationally designed conductive wood demonstrated potential in durable and ultrasensitive pressure-responsive devices and strain sensors.
Effects of Cellular Crossing Paths on Mechanical Properties of 3D Printed Continuous Fiber Reinforced Biocomposite Honeycomb Structures
Ping Cheng, Kui Wang, Yong Peng, Said Ahzi
doi:10.1016/j.compositesa.2023.107972
细胞交叉路径对三维打印连续纤维增强生物复合蜂窝结构机械性能的影响
3D printing continuous fiber reinforced composite (CFRC) has the advantages of manufacturing complex shapes and short production cycles. Due to the anisotropic mechanical properties of continuous fibers, the printing path of the fibers determines the properties of the printed CFRCs. In this paper, a series of novel cellular crossing paths were proposed to print continuous ramie fiber reinforced biocomposite honeycomb structures (CFHSs). The compression, bending, and tensile tests were performed to analyze the effects of cellular crossing paths on the mechanical properties of CFHSs. An assessment method was presented for analyzing the comprehensive mechanical properties of CFHSs printed by different printing paths. The results showed that the CFHSs printed by no-crossing path (Path-1), single-crossing path (Path-3), and double-crossing path (Path-4) exhibited better compression, bending, and tensile properties, respectively. In addition, the samples printed by Path-3 were the most outstanding in the assessments of comprehensive mechanical properties, the comprehensive performance assessment score was 1.5 times that of the single-crossing path (Path-2, minimum score). Thus, an appropriate cellular crossing path could be selected according to the structural load-bearing state, thereby providing higher mechanical properties.
Impact injuries and fire risks generally coexist simultaneously in extreme environments. In this context, it is of great necessity to design impact resistant materials with both flame retardant performance and thermal stability. Here, a multi-functional flame retardant coating was prepared from the combination of silica sol (Si-sol), phytic acid (PA) and expandable graphite (EG) by graft modification with γ-propyl-trimethoxysilane (KH550). Subsequently, hierarchical composites were fabricated using one-pot foaming and brush coating method, where the carbon fiber cloth and coating served as the surface layer, while rigid polyurethane foams (RPUF) acted as the interlayer. The hierarchical structure endowed the RPUF composites with high compression resistance and impact resistance properties. Furthermore, the flame retardant coating could effectively reduce the values of peak heat release rate and peak smoke production rate of RPUF composites by 77.5% and 81.8%, respectively. Therefore, these RPUF composites can effectively prevent impact damage and achieve excellent flame retardancy, making them promising candidates as safety protective materials.
An innovative tunable bimodal porous PCL/gelatin dressing fabricated by electrospinning and 3D printing for efficient wound healing and scalable production
This study presents the development of tunable scaffolds with bimodal porosity comprising poly(ε-caprolactone) (PCL) micro-meshes and PCL/gelatin/ε-polylysine (ε-PL) fibrous layers. Pure PCL scaffolds were prepared using the fused deposition modeling technique featuring grid geometry and interconnected micro-pores, followed by electrospinning to produce PCL/gelatin/ε-PL nanofibrous layers. Field emission scanning electron microscopy was employed to investigate the morphological features of the scaffolds, while the physicomechanical properties were studied using tensile and contact angle tests. Antibacterial performance and skin cell toxicity of the scaffolds were determined by bacterial disc diffusion and viability assays, respectively. Morphological analysis showed the presence of micro-to nano-sized pores in the developed scaffolds. The mechanical test results revealed that the prepared scaffolds exhibited Young's modulus values similar to the human skin with higher strain. The nanocomposite scaffolds were cytocompatible and effectively eradicated common bacteria associated with cutaneous wounds. In light of the aforementioned results along with facile fabrication, the tunable PCL/gelatin/ε-PL porous scaffolds hold great promise for applications in skin wound repair.
