Low velocity impact (LVI) experiments are performed to provide correlations with the simulation results based on numerical modeling of the intralaminar matrix damage and interlaminar delamination damage of composite laminates. The good agreement between the numerical simulation and experimental results provided validation of the numerical modeling approach. The validated numerical modeling is then used in the parametrical assessment of the influence of material properties and model- related parameters on the global LVI deformation responses and the evolution characteristics of the intralaminar and interlaminar damage. It is observed that the element deletion method is not suitable to resolve the element distortion problem induced by the progressive damage. The numerical convergence problem caused by element distortion can be resolved with appropriate selection of threshold value of the critical damage parameter without element deletion. The parametrical numerical investigations showed that the variations of material properties and parameters related to interlaminar damage exhibited significant influence on the LVI global deformation responses and progressive damage evolutions. Meanwhile, insignificant influence of the material properties related to the intralaminar damage was observed for the normal variations within material scatters.
High strength and fatigue performance achieved for L-PBF processed hybrid particle reinforced Al-Cu-Mg composite
Seren Senol, Guichuan Li, Vivek Devulapalli, Etienne Brodu, Kim Vanmeensel
doi:10.1016/j.compositesb.2024.111736
L-PBF加工的杂化颗粒增强Al-Cu-Mg复合材料具有较高的强度和疲劳性能
This study highlights the successful manufacturing of a crack-free, dense, hybrid ex-situ/in-situ particle reinforced (Ti+B4C)/Al-Cu-Mg composite, fabricated by laser powder bed fusion and exhibiting exceptional mechanical performance. In its as-built (AB) state, the composite displays a unique microstructure characterized by equiaxed grains with an average grain size of 1.0 ± 0.3 μm, notable interdendritic microsegregation of Cu, Mg, Mn, and Fe, randomly distributed ex-situ added Ti and B4C particles featuring a surface interaction layer with the metal matrix, and in-situ formed reinforcing particles, such as TiB2 and TiC. After subjecting the material to hot isostatic pressing (HIP) and subsequent aging treatment, dissolution of interdendritically segregated elements occurs, and precipitation of Al2Cu, Al12Mg17, and Al-Fe-Cu-Mn phases is observed. Significantly enhanced fatigue performance is recorded, reaching to 107 cycles at 250 MPa in AB and 330 MPa in HIP state, marking a 32% improvement. The current study highlights the intricate relationship between the different microstructural features in AB and HIPed state, leading to fracture during tensile and fatigue loading conditions.
Plant fibers are a class of biomass resources one of most abundant materials on earth. The bast fiber, as one of the plant fibers with superior specific stiffness and strength, has received constant attention in the field of biocomposites for various industrial sectors. This study is to provide a comprehensive overview of bast fiber composites. The characteristic, chemical composition and performance of five types of most commonly available bast fibers (ramie, jute, kenaf, flax and hemp fibers), and their functionalization in biocomposites are analyzed. The engineering technologies and performance in uses, e.g. flame retardancy, adsorption, reinforcement, biodegradability green sustainability and recyclability of the bast fiber composites are assessed and compiled. The challenges and future development of bast fiber composites are also discussed. The review is expected to provide a platform database but insightful understanding for effective engineering design and broadened applications of bast fiber composites, and for further innovations of functionalized bast fiber composites.
Nanomechanical characterization of carbon nanotube-based composite interfaces tailored by electrophoretic deposition
Dae Han Sung, Sagar M. Doshi, Andrew N. Rider, Erik T. Thostenson
doi:10.1016/j.compositesb.2024.111741
电泳沉积碳纳米管基复合材料界面的纳米力学表征
Carbon nanotube (CNT) addition to composite materials can offer both nanoscale reinforcement and a multifunctional element due to their extraordinary mechanical, thermal and electrical properties. Electrophoretic deposition (EPD) offers a scalable processing technique to incorporate CNTs into conventional fiber-reinforced polymer composites (FRPCs), facilitating the production of unique nanoscale structures in the critical interphase region. In this study, CNTs functionalized with polyethyleneimine (CNT-PEI) were deposited onto a planar substrate via EPD followed by the infusion of epoxy matrix in order to replicate the nanocomposite interphase region present in nanomodified FRPCs. The nanocomposite films have thicknesses ranging from several hundred nanometers to a few microns to represent different fiber-matrix interphase regions found in FRPCs. The morphology and mechanical performance of CNT-PEI/epoxy nanocomposites are examined using atomic force microscopy (AFM) in both tapping and nanoindentation modes. The EPD creates a homogeneously distributed porous CNT network bridged by PEI, forming the pathway of epoxy resin infusion through interconnected pores with diameters less than 100 nm. CNT-PEI/epoxy nanocomposites exhibited significant improvements in stiffness, hardness, and creep resistance compared to constituent porous CNT-PEI films and neat epoxy. The improvement was directly related to the ability of the load bearing CNTs chemically bonded with the epoxy matrix through the grafted PEI, providing an efficient load transfer mechanism. The chemical bond between the porous CNT-PEI and epoxy also produced far greater fracture surface in nanoscale scratch tests compared to unmodified epoxy, indicating the CNT-PEI/epoxy nanocomposite is capable of distributing load and absorbing more energy prior to fracture.
A Statistical Volume Element-based procedure for the prediction of the mechanical and electrical response of an epoxy-PZT self-sensing layer for application in composite laminates
Michele Gulino, Tommaso Maria Brugo, Alessandro Pirondi, Andrea Zucchelli
doi:10.1016/j.compscitech.2024.110772
基于统计体积元的预测环氧树脂- pzt自感层的机械和电气响应的程序，用于复合材料层合板
Structural Health Monitoring (SHM) techniques are being developed to continuously oversee defects in composite structures. Within this context, research is focusing on the development of new types of sensors with high sensitivity and a proper integration in the laminate.In this work, the mechanical and electrical properties of a recently developed piezoelectric composite material made of a Lead Zirconate Titanate (PZT) powder embedded in an epoxy matrix are evaluated with finite element simulations of plane strain Statistical Volume Elements (SVEs). The homogenized properties are then implemented in a second finite element model of a composite specimen with the embedded self-sensing material and loaded in compression. The electrical sensitivity is evaluated as a function of the distance between the signal electrodes.The results show that the finite element models with the homogenized properties have decreasing sensitivity with increasing electrodes distance, in agreement with the experimental results from another work, in which Glass Fiber Reinforced Polymer (GFRP) laminates with the embedded piezoelectric composite are loaded in compression and tested for output signal.
