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【新文速递】2024年10月1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

Composite Structures

Examining infrared thermography based approaches to rapid fatigue characterization of additively manufactured compression molded short fiber thermoplastic composites

P. Pathak, S. Gururaja, V. Kumar, D. Nuttall, A. Mahmoudi, M.M. Khonsari, U. Vaidya

doi:10.1016/j.compstruct.2024.118610

研究基于红外热成像的增材制造压缩成型短纤维热塑性复合材料快速疲劳表征方法

A novel additive manufacturing (AM) methodology combined with a compression molding (CM) process has been previouslydeveloped to optimize the microstructure of short fiber thermoplastic (SFTs) composites with higher fiber alignment and lower porosity, yielding superior stiffness, strength, and structural integrity. The current work examines the efficacy of the ‘passive’ infrared thermography (IRT) techniques for rapid fatigue characterization of SFTs that use the surface temperature evolution during cyclic loading due to self-heating as a fatigue indicator. A comparison of fatigue limits obtained from traditional stress-life (SN) (≈53.1% σ_uts) and IRT (≈54.1% σ_uts) shows a close match. However, the SN curve required 18 specimens and two weeks of continuous cyclic testing, while IRT used three specimens with 5 h of testing. Thus, the IRT approach provides an accelerated testing framework for rapidly estimating the fatigue limit. Additionally, existing phenomenological approaches to IRT fatigue characterization have been examined.

之前开发的一种新型增材制造(AM)方法与压缩成型(CM)工艺相结合,可优化短纤维热塑性塑料(SFT)复合材料的微观结构,使其具有更高的纤维排列度和更低的孔隙率,从而获得优异的刚度、强度和结构完整性。目前的工作研究了 “被动 ”红外热成像(IRT)技术在 SFT 快速疲劳表征方面的功效,该技术使用循环加载期间由于自加热而产生的表面温度变化作为疲劳指标。通过比较传统应力寿命(SN)(≈53.1% σ_uts)和 IRT(≈54.1% σ_uts)获得的疲劳极限,结果显示两者非常接近。不过,SN 曲线需要 18 个试样和两周的连续循环测试,而 IRT 只需要 3 个试样和 5 小时的测试。因此,IRT 方法为快速估计疲劳极限提供了一个加速测试框架。此外,我们还研究了 IRT 疲劳表征的现有现象学方法。


Composites Part A: Applied Science and Manufacturing

Joule heating of carbon fibre tapes – A low-cost approach for automated dry fibre deposition

Shimin Lu, Peihao Song, Lee Harper, Thomas Turner

doi:10.1016/j.compositesa.2024.108498

碳纤维带的焦耳加热-一种低成本的自动干纤维沉积方法

Joule heating is potentially a low-cost option for activating the binder on the surface of carbon fibre tapes during automated dry fibre placement (ADFP). In this paper, the electrical contact resistance between a carbon fibre tape and cylindrical electrodes is characterised experimentally using a tabletop rig to replicate the process conditions encountered during ADFP. This rig is used to study a range of wrap angles, fibre tensions and temperatures to inform the design of a Joule heating setup for a lab-scale ADFP fibre deposition rig. A validated model has been developed to predict the tape temperature at the nip point for different current inputs and deposition velocities. Increasing both fibre tension and wrap angle are found to reduce contact resistance and increase heating efficiency. A nip point temperature of 200 °C can be achieved by Joule heating for a single carbon fibre tape at a deposition velocity of 100 m m/s, using a power of 110 W. This equates to a 17 % reduction in energy compared to laser heating.

焦耳加热是一种潜在的低成本选择,可以在自动干纤维放置(ADFP)过程中激活碳纤维带表面的粘合剂。在本文中,碳纤维胶带和圆柱形电极之间的电接触电阻进行了实验表征,使用桌面设备来复制ADFP过程中遇到的工艺条件。该装置用于研究一系列缠绕角度、纤维张力和温度,为实验室规模ADFP纤维沉积装置的焦耳加热装置设计提供信息。在不同的电流输入和沉积速度下,建立了一个有效的模型来预测带在掐点处的温度。增加纤维张力和包覆角可以降低接触电阻,提高加热效率。通过焦耳加热,以100 m m/s的沉积速度,使用110 W的功率,可以实现200 °C的夹点温度。与激光加热相比,这相当于减少了17% %的能量。



来源:复合材料力学仿真Composites FEM
ACTAdditive疲劳复合材料增材UMElectric材料
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首次发布时间:2024-11-27
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【新文速递】2024年10月9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

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