Composite Structures最新文献_第7页

Debonding and surface degradation of protective coatings of wind turbine blades due to fatigue in stochastic rain scenario

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-15 DOI: 10.1016/j.compstruct.2025.118973

Nikesh Kuthe , Puneet Mahajan , Suhail Ahmed , Leon Mishnaevsky Jr.

The wind turbine blade is a layered structure consisting of coating, putty and composite laminate. Repetitive raindrop impacts of a random nature can cause fatigue damage in the layers leading to interlayer debonding. This study introduces a computational model that integrates cohesive elements at the coating-putty and putty-composite interfaces. The model incorporates shockwave interactions due to repeated impacts to study the fatigue life of the blade coating, including debonding-induced erosion. A Coupled Eulerian-Lagrangian (CEL) analysis calculates impact pressures from individual raindrops of different diameters on a blade, developing a library of pressure time histories for each diameter. A stochastic rain scenario is generated to define raindrop size distribution with respect to time and location. The impact pressure library is integrated with the stochastic rain scenario to predict localized stresses from repetitive impacts. Fatigue damage evolution laws are employed for coating and cohesive elements to estimate the cumulative damage growth in the coating and interface between the layers for each impact. The coating and putty are assumed to be viscoelastic, and the composite substrate is taken as elastic. The coating and cohesive zone’s damage initiation and evolution equations are implemented via a user-defined subroutine in ABAQUS/Explicit. The work’s notable contribution is the identification of failure mechanisms in a stochastic rain scenario at varying impact velocities. It highlights that debonding at the coating-putty interface primarily drives coating erosion, rather than damage to the coating itself. The model’s prediction for the number of drop impacts leading to erosion closely matches those with the Rain Erosion Test in the literature and are corroborated by field observations.

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引用次数: 0

Stochastic vibration behaviors of functionally graded graphene platelets reinforced composite joined conical-cylindrical-conical shell with variable taper under moving random loads

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-15 DOI: 10.1016/j.compstruct.2025.118970

Zhen Li , Qingshan Wang , Qing Yang , Bin Qin

This paper proposed a unified dynamic model for investigating the stochastic vibration behaviors of functionally graded graphene platelets reinforced composite (FG-GPLRC) joined conical-cylindrical-conical shell with variable taper under moving random loads by employing differential quadrature finite element method (DQFEM) and pseudo excitation method (PEM) and Newmark-β method on the basis of the first order shear deformation shell theory (FSDST) in conjunction with the modified Halpin–Tsai model and rule of mixture. The adjacent shell segments are connected by means of common nodes and the boundary conditions of FG-GPLRC joined conical-cylindrical-conical shell with variable taper are simulated by employing penalty function method. Four distributions of GPLs and two moving paths are considered. Then, the effective of the proposed model are verified by convergence analysis and model verification. Finally, the stochastic vibration behaviors of FG-GPLRC joined conical-cylindrical-conical shell with variable taper under moving random loads are investigated systematically by investigating the effects of model parameters including the distribution of GPLs, weight fraction of GPLs, observation position, moving path, semi-vertex angle, thickness and radius on the power spectral density (PSD) and time-varying root mean square (RMS) of displacement response. This investigation can offer the theoretical basis for predicting the stochastic vibration behaviors of FG-GPLRC joined conical-cylindrical-conical shell with variable taper under moving random loads.

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引用次数: 0

Arbitrary multiphase hybrid stress finite element method for composite materials

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-15 DOI: 10.1016/j.compstruct.2025.118974

Wenyan Zhang, Ran Guo, Wei Xu

In this paper, A new Arbitrary Multiphase Hybrid Stress Finite Element (AMHSFE) and its element formulation are established, for which the number of material phases (ph ≥ 2) and the number of element sides are arbitrary. A new modified complementary energy functional considering plasticity is proposed, into which the continuity of displacements and the continuity of tractions on the phase interface of the multiphase material are introduced by Lagrange multiplier method, based on the newly established AMHSFE model and the theory of hybrid stress element method. A new stress function that fully accounts for the reciprocal stress functions at multiple interfaces is constructed. By comparing the results with Finite Element Method (FEM) models, the accuracy and validity of the new AMHSFE considering plasticity is verified. The effect of different terms of the three types of stress functions and the number of integration points on the accuracy of the calculations is discussed. At the end of the article, the accuracy of AMHSFE is further demonstrated by a high volume fraction Particulate Reinforced Composites (PRCs) example, from which it is possible to foresee the possibilities and advantages of AMHSFE for the numerical simulation of tremendous amounts of particle phases of real multiphase materials.

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引用次数: 0

Enhancing torsional behavior of RC beams: The potential of ultra-high performance concrete (UHPC)

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-14 DOI: 10.1016/j.compstruct.2025.118950

Cong Zhou , Jianqun Wang , Xudong Shao , Lifeng Li , Minghong Qiu

The potential of ultra-high performance concrete (UHPC) for enhancing the torsional behavior of RC beams is evaluated in this study, as a significant gap has been identified on this topic in the present. Pure torsion tests were conducted on nine specimens, including one un-strengthened and eight UHPC-strengthened RC beams. Refined finite element (FE) models were established using ATENA software to simulate the full-range torsional behavior of the specimens. Results from experiments and FE simulations indicate that the utilization of UHPC significantly improves the torsional resistance of RC beams, with an increase of 136.5 %

\sim

488.5 % in cracking torque and an increase of 21.8 %

\sim

593.2 % in ultimate torque. Two-sided wrapping scheme is not recommended since the failure mechanisms in those beams will induce considerable safety risks. Three-sided wrapping scheme could serve as an alternative solution to the fully-wrapped scheme if the latter cannot be realized due to space limitation. The surfaces of the RC beam should be roughened prior to the application of UHPC layers to ensure reliable bonding performance between them. The decision to incorporate steel bars into the UHPC layers should comprehensively consider the costs, constraints in dimensions and increase in torsional capacity. Finally, a theoretical formula was proposed for predicting the torsional capacity of UHPC-strengthened RC beams utilizing 4-sided wrapping configuration. The experimental results from six fully-wrapped strengthened beams in this study were used to validate the proposed formula. The mean value and standard deviation of the ratio between the theoretically obtained and experimentally obtained results were 1.10 and 0.16, respectively, indicating that the proposed formula provides a satisfactory prediction of the torsional capacity.

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引用次数: 0

Optimization of critical buckling load for variable stiffness composites using the lamination parameters as the field variables

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-13 DOI: 10.1016/j.compstruct.2025.118945

Eralp Demir , Ali Rashed

Buckling is a critical design concern for thin-walled structures and fiber-reinforced composite materials because it occurs with much lower strains than in failure. In this study, an in-house code is developed to optimize the critical buckling load using the lamination parameters as a design variable. The manufacturing steering curvature constraints are directly applied on the lamination parameters for the first time during optimization. The variable stiffness design revealed an approximately 160% improvement in the buckling load with respect to the optimal constant stiffness. The improvement in the critical buckling load ratio is over 400% with respect to the quasi-isotropic case, which is consistent with previous findings (Wu et al., 2015). The critical buckling load is 27% less when two opposite edges are clamped and two opposite edges are free compared to the ideal simply supported out-of-plane displacement boundary conditions that were used in previous optimization studies (Wu et al., 2015, Hao et al. 2019, Wu et al. 2012, Setoodeh et al. 2009, IJsselmuiden et al. 2010). The critical load ratio serves as the objective function when Neumann boundary conditions are employed, since membrane reactions remain unchanged throughout the optimization process, unlike in the case of Dirichlet boundary conditions. In addition, a widely accepted optimum fiber angle distribution, suggested in Gürdal et al. (2008), is implemented in a user-defined subroutine (UMAT) of Abaqus® to compare the buckling response of constant and variable stiffness of a plate.

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引用次数: 0

Aero-thermo-elastic stability analysis of supersonic variable stiffness sandwich panels using refined layerwise models

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-13 DOI: 10.1016/j.compstruct.2025.118920

J.A. Moreira , F. Moleiro , A.L. Araújo , A. Pagani

This work investigates the linear aero-thermo-elastic flutter and buckling stability of supersonic soft core sandwich panels with variable stiffness composite skins using refined layerwise finite element models based on shear deformation theories devoid of thickness stretching, as well as quasi-3D theories with thickness stretching involving Lagrange

z

-expansions. The proposed numerical applications of soft core sandwich panels, with either unidirectional or curvilinear fibres, highlight that the spatially varying fibre orientations, core thickness ratio and applied thermal loads significantly influence the aero-thermo-elastic response behaviour. Additionally, it is concluded that high-order layerwise models with thickness stretching are often crucial to properly capture the complex aeroelastic behaviour of thermally loaded sandwich panels experiencing flutter due to high-order modes. Nonetheless, the layerwise first-order shear deformation model ensures a fair compromise between numerical accuracy and computational efficiency when flutter arises in the first two modes.

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引用次数: 0

Inverse design of a petal-shaped honeycomb with zero Poisson’s ratio and bi-directional tunable mechanical properties

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-13 DOI: 10.1016/j.compstruct.2025.118967

Ze-Yu Chang , Hai-Tao Liu , Guang-Bin Cai , Dong Zhen

Zero Poisson’s ratio (ZPR) honeycombs are widely used in aerospace applications due to their high load carrying capacity, tunable performance and lightweight. However, its structural design is difficult and often requires designers to have extensive experience. With the gradual development of artificial intelligence, it becomes possible to obtain structural configurations using meta-models and desired mechanical properties. In this paper, a petal-shaped honeycomb (PSH) with bi-directional tunable mechanical properties possessing ZPR effect is designed. Parametric modelling and Latin hypercube sampling (LHS) are applied to reveal the effect of structural parameters on the bi-directional mechanical properties. Combined with Python scripts to automate the running of finite element analyses and complete the collection of results. An artificial neural network (ANN) is improved to achieve the performance prediction of the PSH with a minimum error of only 0.032%. The inverse design of the PSH is completed based on the mechanical properties required for the conceptual application with a minimum error of 2.375%. An automatic design system for PSH is proposed by integrating parametric models, Python scripts and modified ANN. The overall process reduces human control time through the automation of scripts, improves the honeycomb design efficiency, and provides a new systematic approach for the design of ZPR honeycombs.

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引用次数: 0

Hierarchical multiscale fracture modeling of carbon-nitride nanosheet reinforced composites by combining cohesive phase-field and molecular dynamics

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-13 DOI: 10.1016/j.compstruct.2025.118942

Qinghua Zhang , Navid Valizadeh , Mingpeng Liu , Xiaoying Zhuang , Bohayra Mortazavi

Understanding the fracture mechanisms in composite materials across scales, from nano- to micro-scales, is essential for an indepth understanding of the reinforcement mechanisms and designing the next generation of lightweight, high-strength composites. However, conventional methods struggle to model the complex fracture behavior of nanocomposites, particularly at the fiber–matrix interface. The phase-field regularized cohesive fracture model has proven to be effective in simulating crack initiation, branching, and propagation; however, capturing the cohesive fracture strength at smaller scales remains a significant challenge. This study introduces a novel approach that combines an energy-based star-convex decomposition cohesive phase-field fracture model with molecular dynamic simulations to explore the thickness dependency of nanocomposite mechanical properties. The proposed framework enables hierarchical modeling of the mechanical and fracture behaviors of carbon-nitride nanosheet-reinforced composites. The developed model could reveal complex fracture processes across different scales and highlight critical scaling effects. This methodology provides an efficient solution for uncovering hierarchical fracture mechanisms in reinforced nanocomposites, offering valuable insights into their fracture behavior and strengthening mechanisms.

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引用次数: 0

Free vibration behaviour of curved Miura-folded bio-inspired helicoidal laminated composite cylindrical shells using HSDT assisted by machine learning-based IGA 使用基于机器学习的 IGA 辅助 HSDT，研究曲面三浦折叠生物启发螺旋形层压复合圆柱壳的自由振动特性

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-12 DOI: 10.1016/j.compstruct.2025.118933

Aman Garg , Weiguang Zheng , Mehmet Avcar , Mohamed-Ouejdi Belarbi , Raj Kiran , Li Li , Roshan Raman

Deployable structures, which can be compacted into small spaces and later deployed into their desired configurations, have gained significant attention due to their versatility. Origami-inspired structures, in particular, leverage the principles of origami to achieve compactness and deploy ability. This study focuses on predicting the free vibration behaviour of Miura-folded laminated composite cylindrical shells, which are modelled using bio-inspired helicoidal schemes. The analysis is conducted through isogeometric analysis (IGA) based on higher-order shear deformation theory (HSDT). A Gaussian Process Regression (GPR) machine learning surrogate is employed to predict the IGA parameters, specifically the knot vectors, which are used to accurately model the geometry of the shells. The performance of the proposed approach is validated by comparing the results with those obtained without the surrogate model. The findings of this study serve as a benchmark for future research on the free vibration behaviour of origami-inspired cylindrical shells and highlight the potential of using machine learning surrogates in structural analysis.

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引用次数: 0

A novel micro-mechanical model for continuous carbon fiber-reinforced composites: Effect of fiber surface roughness on mechanical behaviors 连续碳纤维增强复合材料的新型微观力学模型：纤维表面粗糙度对力学行为的影响

IF 6.3 2区材料科学 Q1 MATERIALS SCIENCE, COMPOSITES

Composite Structures

Pub Date : 2025-02-11 DOI: 10.1016/j.compstruct.2025.118960

Heng Cai , Jiale Xi , Yuan Chen , Lin Ye

The fiber surface roughness determines the interface contact between carbon fiber and resin of composites, and its effect is crucial to be investigated. This study develops a micro-mechanical model considering the surface morphology of carbon fibers to examine the impact of microscopic geometric features on the macroscopic mechanical behaviors of composites. The morphological characteristics of the carbon fiber surface were well captured through image processing based on the microscopically scanned images of fiber cross-sections to determine the average depth-to-width ratio of grooves on the fiber surface. Further, based on statistical analysis, the proposed model considering surface roughness of carbon fibers were developed to evaluate the effective mechanical properties of composites. Then, both the experimental and theoretical results demonstrated that the proposed model exhibits a 3 % reduction in the relative error for predicting the transverse modulus when compared to the standard model indicating a minimal effect of surface roughness on the mechanical responses in this case. However, further numerical analyses using an average depth-to-width ratio twice that of the initial proposed model revealed a 4.18 % increase in the transverse elastic modulus. By calculation, the transverse tensile strength was 39.43 MPa when using the proposed model, demonstrating an increment of 5.1 % in strength when compared to that using the standard model.

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引用次数: 0