【新文速递】2024年10月29日复合材料SCI期刊最新文章

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今日更新：Composite Structures 1 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Science and Technology 1 篇

Composite Structures

Three-dimensional elasticity solutions for doubly-curved composite shells by extended differential quadrature method

G.M. Kulikov

doi:10.1016/j.compstruct.2024.118647

用扩展微分正交法求解双弯曲复合材料壳的三维弹性

This paper presents the three-dimensional (3D) stress analysis of doubly-curved composite shells with general boundary conditions using the strong sampling surfaces (SaS) formulation. The SaS method is based on the choice of SaS parallel to the middle surface and located at Chebyshev polynomial nodes to introduce the displacements of these surfaces as unknown functions that leads to a non-conventional shell formulation, in which strain–displacement and stress–strain relationships are represented in terms of SaS displacements. This is due to the use of Lagrange polynomials in approximating displacements, strains and stresses in the thickness direction. The outer surfaces are not included into a set of SaS that makes it possible to uniformly minimize the error ca used by Lagrange interpolation. The strong SaS formulation, based on direct integration of elasticity equilibrium equations in the thickness direction by the extended differential quadrature (EDQ) method, can be applied efficiently for high-precision calculations of doubly-curved composite shells with clamped and free edges. This is because in the SaS/EDQ formulation, displacements, strains and stresses of SaS are interpolated in a rectangular domain specified in a curvilinear coordinate system using a Chebyshev-Gauss-Lobatto grid and Lagrange polynomials are also used as basis functions. The proposed approach deals with equilibrium equations in terms of SaS stresses, avoiding the integration of second order differential equations in terms of SaS displacements, that greatly simplifies the implementation of the EDQ method.

本文采用强采样面公式，对具有一般边界条件的双弯曲复合材料壳进行了三维应力分析。SaS方法是基于选择与中间表面平行且位于切比雪夫多项式节点的SaS，将这些表面的位移作为未知函数引入，从而导致非常规的壳公式，其中应变-位移和应力-应变关系由SaS位移表示。这是由于在厚度方向上使用拉格朗日多项式近似位移、应变和应力。外表面不包括在一组sa中，这使得可以均匀地最小化拉格朗日插值所使用的误差。采用扩展微分正交法（EDQ）对弹性平衡方程在厚度方向上直接积分的强SaS公式，可有效地应用于夹紧边和自由边双弯曲复合材料壳的高精度计算。这是因为在SaS/EDQ公式中，SaS的位移，应变和应力在曲线坐标系中使用切比舍夫-高斯-洛巴托网格在指定的矩形域内插值，并且拉格朗日多项式也用作基函数。所提出的方法处理的平衡方程以sa应力，避免了二阶微分方程的积分以sa位移，大大简化了EDQ方法的实现。

Composites Part A: Applied Science and Manufacturing

Shape-programmable hard-magnetic soft actuators with high magnetic particle content via digital light processing method

Xin Li, Dingcong Zhang, Huiru Wang, Rui Yang, Hongyan Yuan

doi:10.1016/j.compositesa.2024.108554

通过数字光处理方法实现高磁粉含量的形状可编程硬磁软执行器

In this work, we developed a novel hard-magnetic photosensitive suspension with high solid loadings of 50 wt% for digital light processing 3D printing. The suspension combining photosensitive resin and reactive diluent can retain stability for 6 h. The printed materials from the suspension achieve a low modulus of below 900 kPa and high remanence of 83.7 kA/m. The suspension’s cure behavior was studied in detail to obtain the optimal printing parameters. The printing error of the small structures with feature size of about 1000 μm is kept below 20 %. Moreover, we proposed an efficient magnetization programming strategy for hard-magnetic soft actuators with desirable shapes based on the rod model considering the non-magnetic load. The accuracy and reliability of the strategy are verified by the experiment results. Finally, we designed and fabricated a “flower” using our method, achieving its closing action in accordance with the prescribed shape.

在这项工作中，我们开发了一种新型的硬磁光敏悬浮液，固体负载高达50 wt%，用于数字光处理3D打印。由光敏树脂和活性稀释剂组成的悬浮液可保持6 h的稳定性。从悬浮液中打印的材料实现了低于900 kPa的低模量和83.7 kA/m的高剩余率。对悬浮液的固化性能进行了详细的研究，得到了最佳的打印参数。特征尺寸在1000 μm左右的小结构的打印误差保持在20% %以下。此外，在考虑非磁性负载的基础上，提出了一种具有理想形状的硬磁软执行器的有效磁化规划策略。实验结果验证了该策略的准确性和可靠性。最后，我们用我们的方法设计和制作了一个“花”，实现了它按照规定形状闭合的动作。

Composites Science and Technology

Covalently engineering novel sandwich-like rGO@POSS nanofillers for high-performance dielectric energy storage of PVDF film capacitor

Hui Liu, Mingming Ding, Xuecheng Chen, Zhaotian Ba, Zhewen Ma, Lili Ma, Xin Wen, Pingan Song, Qingquan Lei

doi:10.1016/j.compscitech.2024.110938

共价工程新型三明治状rGO@POSS纳米填料用于PVDF薄膜电容器的高性能介电储能

With the development of modern electronic and electrical industry, it is still a great challenge to develop poly(vinylidene fluoride) (PVDF) based dielectric capacitors with high energy storage capability. Herein, a novel sandwich-like nanofiller was constructed via covalently grafting polyhedral oligomeric silsesquioxane onto graphene oxide nanosheets (GO@POSS), further PVDF/rGO@POSS film were fabricated via solvent-casting and in-situ thermal reduction processes. The results indicated that the grafting of POSS promoted the uniform dispersion of nanofillers to realize strong interfacial interaction with PVDF matrix. The optimal PVDF film containing 0.75wt% rGO@POSS (0.75PGP-60) exhibited larger dielectric constant (εr = 13.32) and higher breakdown strength (Eb = 339.1 MV·m-1), thus resulting in synchronous improvements on energy density (Ue = 5.42 J·cm-3) and charge-discharge efficiency (η = 73.1%), which increased by 95.0% and 19.4% compared to pure PVDF, respectively. Meanwhile, it presented excellent cycling stability with 97.6% energy density retention after 10000th cycles. The improved energy storage capability was attributed to reasonably-designed sandwich-like nanofiller: the formation of rGO micro-capacitors raised the dielectric constant of PVDF nanocomposites, while the insulative POSS layer helped to improve its breakdown strength and decrease its dielectric loss. The current work provides a novel and efficient paradigm to design PVDF nanocomposites with promising dielectric properties and energy storage capacity, and further contributes to broadening the practical applications of advanced dielectric capacitors.

随着现代电子和电气工业的发展，开发具有高能量存储能力的聚偏二氟乙烯（PVDF）基电介质电容器仍然是一项巨大的挑战。为此，通过共价接枝聚多面体低聚倍半硅氧烷（POSS）到石墨烯氧化物纳米片（GO@POSS）上，构建了一种新型的层状纳米填料。通过溶剂浇铸和原位热还原过程制备了PVDF/rGO@POSS薄膜。结果表明，POSS接枝促进了纳米填料的均匀分散，实现了与PVDF基体的强界面相互作用。含有0.75wt% rGO@POSS（0.75PGP-60）的PVDF薄膜具有较大的介电常数（εr = 13.32）和更高的击穿强度（Eb = 339.1 MV·m-1），从而实现了能量密度（Ue = 5.42 J·cm-3）和充放电效率（η = 73.1%）的同步提高，分别比纯PVDF提高了95.0%和19.%。同时，它具有出色的循环稳定性，在10000次循环后仍保留了97.6%的能量密度。改进后的能量存储能力归因于合理设计的三明治状纳米填料：石墨烯微电容器的形成提高了PVDF纳米复合材料的介电常数，而绝缘的POSS层有助于提高其击穿强度并降低其介电损耗。该工作为设计具有潜在的介电性能和能量存储能力的PVDF纳米复合材料提供了一种新颖而有效的方法，并进一步促进了先进电容器的实际应用的扩展。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年10月8日复合材料SCI期刊最新文章

今日更新：Composite Structures 1 篇，Composites Part A: Applied Science and Manufacturing 1 篇Composite StructuresA semi-analytical model for predicting the shear buckling of laminated composite honeycomb cores in sandwich panelsJasotharan Sriharan, Marcelo Dias, Sondipon Adhikari, Dilum Fernandodoi:10.1016/j.compstruct.2024.118629复合材料夹层板蜂窝芯剪切屈曲的半解析模型Laminated composite honeycomb cellular core sandwich panels are widely utilized in various industries due to their exceptional stiffness-to-weight ratio and strength characteristics. Current analytical models often simplify honeycomb cores as homogenized continua, effectively predicting stiffness but falling short in capturing crucial failure modes, particularly shear buckling of honeycomb core walls. Existing theoretical studies on shear buckling are limited to isotropic materials and specific honeycomb geometries. While numerical models can simulate cell wall buckling, their computational demands render them impractical for large structures employing sandwich panels. This paper introduces a novel, simplified semi-analytical approach that accurately predicts the shear buckling load of laminated composite honeycomb cellular cores. The model accounts for bend-twist coupling effects and rotational restraints at laminate wall boundaries. To validate the proposed approach, predictions are compared with finite element analysis results for hexagonal honeycomb cores and cores of varying shapes, incorporating diverse fibre lay-up configurations. The findings demonstrate excellent agreement between the proposed approach and finite element analysis, indicating its reliability in predicting shear buckling. This research addresses the gap in existing methodologies by offering a practical and efficient tool for predicting shear buckling in laminated composite honeycomb cores, extending applicability beyond isotropic materials and specific honeycomb geometries. The proposed approach holds promise for optimizing the design and structural integrity of sandwich panels, impacting industries relying on these lightweight and high-performance structures.层压复合材料蜂窝芯夹芯板以其优异的刚度重量比和强度特性，广泛应用于各行业。目前的分析模型通常将蜂窝芯简化为均质连续体，有效地预测了刚度，但在捕捉关键的破坏模式，特别是蜂窝芯壁的剪切屈曲方面存在不足。现有的剪切屈曲理论研究仅限于各向同性材料和特定的蜂窝几何形状。虽然数值模型可以模拟细胞壁屈曲，但其计算要求使其无法用于采用夹层板的大型结构。本文介绍了一种新的、简化的半解析方法，可以准确地预测层合复合材料蜂窝芯的剪切屈曲载荷。该模型考虑了层合壁边界处的弯扭耦合效应和旋转约束。为了验证所提出的方法，将预测结果与六边形蜂窝芯和不同形状的芯的有限元分析结果进行了比较，其中包含不同的纤维铺设配置。结果表明，该方法与有限元分析结果非常吻合，表明了该方法预测剪切屈曲的可靠性。本研究通过提供一种实用而有效的工具来预测层压复合材料蜂窝芯的剪切屈曲，从而解决了现有方法中的空白，将适用性扩展到各向同性材料和特定蜂窝几何形状之外。所提出的方法有望优化夹层板的设计和结构完整性，影响依赖于这些轻质高性能结构的行业。Composites Part A: Applied Science and ManufacturingFractographic investigation of carbon/epoxy PRSEUS composites exposed to flame after compressive failureDounia Boushab, Aniket Mote, Matthew W. Priddy, Santanu Kundu, Qingsheng Wang, Jaime C. Grunlan, Charles U. Pittman, Thomas E. Lacydoi:10.1016/j.compositesa.2024.108507压缩破坏后碳/环氧复合材料在火焰下的断口形貌研究After a structural-related composite aircraft crash, a fractographic forensic analysis of the damaged surfaces is typically performed to assess the root causes of mechanical failures. Such accident reconstruction efforts, however, can be impeded if the aircraft catches on fire on the ground (i.e., a post-crash fire occurs), where flames or heat exposure can obscure or destroy the fracture surface morphologies of the fibers (i.e., the primary load carrying constituent). In this study, carbon/epoxy Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) skin-stringer assemblies were subjected to uniaxial compression and subsequently exposed to direct flame using a Bunsen burner. Specimens were oriented parallel, orthogonal, and at 45° to the flame axis for durations of 60 s. Additional vertical burn tests were performed for durations up to 300 s. Fractographic inspection of the failure surfaces before and after flame exposure was performed using a combination of destructive sectioning and scanning electron microscopy. The warp-knitted skin (fascia) surrounding the pultruded rod effectively served as a thermal protection layer, which shielded the rod’s broken filaments from significant thermal degradation and facilitated the identification of microbuckling and other mechanical failure mechanisms. This suggests that the presence of fascia, bulkheads, ribs, skins, and other intermediate layers in aircraft structures may significantly shield underlying principal structural element failure surfaces from fire exposure, facilitating post-crash forensic assessments of composite aircraft. Additionally, the through-thickness VectranTM stitching remained intact even after extended flame exposure, suggesting that such stitching can enhance the fire resistance of composite structures.在与结构相关的复合材料飞机坠毁后，通常会对受损表面进行断口学法医分析，以评估机械故障的根本原因。然而，如果飞机在地面着火(即坠机后发生火灾)，这种事故重建工作就会受到阻碍，因为火焰或热暴露会模糊或破坏纤维(即主要承载成分)的断裂表面形态。在这项研究中，碳/环氧拉挤杆缝高效统一结构(PRSEUS)皮肤弦组件进行单轴压缩，随后使用本生灯直接暴露在火焰中。在60 s的时间内，样品与火焰轴平行、正交并呈45°方向。还进行了持续时间长达300 秒的额外垂直燃烧试验。使用破坏性切片和扫描电子显微镜对火焰暴露前后的失效表面进行断口学检查。拉伸杆周围的经编皮肤(筋膜)有效地充当热保护层，保护杆的断裂细丝免受明显的热降解，并有助于识别微屈曲和其他机械失效机制。这表明飞机结构中筋膜、舱壁、肋、表皮和其他中间层的存在可以显著地保护潜在的主要结构元件失效面免受火灾的影响，从而促进复合材料飞机坠毁后的法医评估。此外，即使在长时间的火焰暴露后，通过厚度的VectranTM拼接仍然保持完整，这表明这种拼接可以增强复合材料结构的耐火性。来源：复合材料力学仿真Composites FEM