【新文速递】2024年1月30日复合材料SCI期刊最新文章

6小时前浏览15

今日更新：Composite Structures 1 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Part B: Engineering 3 篇，Composites Science and Technology 1 篇

Composite Structures

An efficient parameterized simulation framework for 3D scarf-repaired composite laminates

Zhenyu Wang, Yimeng Shan, Bin Fu, Han Yan, Yinghua Liu, Xuefeng Yao

doi:10.1016/j.compstruct.2024.117934

三维带状修复复合材料层合板的有效参数化仿真框架

This paper proposes a parameterized simulation framework for predicting the load-bearing capacity of 3D scarf-repaired composite laminates which remarkably reduces the modeling time from several hours to just a few seconds. The specific implementation is demonstrated through a detailed step-by-step explanation. The main contribution lies in: (1) By introducing a reusable geometric partitioning method for composite layers and implementing a partitioning method-based numbering scheme for element and node, the effective management of element and node IDs of elements and nodes in such complex 3D models is greatly facilitated; (2) By ingeniously combining open-source meshing tools and text rewriting techniques, a highly efficient approach has been developed to construct complete models for such structures, showcasing the remarkable potential of these existing techniques in this field. The reliability of the efficient parameterized simulation framework proposed in this study is verified through the comparison between strength values acquired from progressive damage analysis (PDA) and experiment data reported in the existing literature.

本文提出了一种参数化的三维复合材料带修复层合板承载能力预测仿真框架，将建模时间从几个小时缩短到几秒钟。通过详细的一步一步的解释来演示具体的实现。主要贡献在于:(1)通过引入可重用的复合层几何划分方法，实现基于划分方法的元素和节点编号方案，极大地方便了复杂三维模型中元素和节点的元素和节点id的有效管理;(2)通过将开源网格工具和文本重写技术巧妙地结合起来，开发了一种高效的方法来构建此类结构的完整模型，展示了这些现有技术在该领域的显着潜力。通过将渐进损伤分析(PDA)得到的强度值与已有文献报道的实验数据进行对比，验证了本文提出的高效参数化仿真框架的可靠性。

Composites Part A: Applied Science and Manufacturing

In-situ consolidation deformation of composite laminate with gaps of various widths

Shu Minakuchi, Pavel Simacek, Suresh G. Advani

doi:10.1016/j.compositesa.2024.108054

含不同宽度缝隙的复合材料层板原位固结变形

Gaps between prepreg tapes, which occur when prepreg tapes are placed automatically, cause concave deformation of the laminate during consolidation, which degrades the quality of the cured laminate. However, this in-situ concave deformation has never been measured. This study measures consolidation deformation of a cross-ply thermosetting composite laminate containing gaps of various widths at the middle layer. A unique fiber-optic-based shape sensor is used for the in-situ deformation monitoring and the deformation during autoclave pressurization and heating is presented. The results indicate that the deformation phenomenon depends on whether the upper bagging-side layer bridging the gap contacts the tool-side layer below the gap as it sinks into the gap during consolidation. The consolidation process reveals when the gap width is narrow, the fibers and the resin from the prepreg layer flow into the gap and displace upwards the sunken upper layer, partially reducing the concave deformation. One attempt to suppress gap-induced deformation is also made by using a curing condition inspired by the observation and understanding of this deformation mechanism.

预浸胶带自动放置时产生的间隙会导致层压板在固结过程中产生凹形变形，从而降低固化层压板的质量。然而，这种原位凹变形从未被测量过。本研究测量了在中间层含有不同宽度间隙的交叉层热固性复合材料层板的固结变形。提出了一种独特的基于光纤的形状传感器，用于现场变形监测，并提出了高压灭菌器加压和加热过程中的变形。结果表明，变形现象取决于固结过程中架起间隙的上部装袋层在下沉过程中是否与间隙下方的工具层接触。固结过程表明，当间隙宽度较窄时，预浸料层中的纤维和树脂流入间隙并向上置换下沉的上层，部分减小了凹变形。通过对这种变形机制的观察和理解，提出了一种固化条件来抑制间隙引起的变形。

Composites Part B: Engineering

Fabrication of room temperature self-healing, robust superhydrophobic coatings via spraying dual cross-linking supramolecular silicone polymer/SiO2 composite

Jinqiu Tao, Lei Dong, Yuanlong Wu, Xudong Liu, Junhao Xie, Hao Wu, Qianping Ran

doi:10.1016/j.compositesb.2024.111245

通过喷涂双交联超分子有机硅聚合物/SiO2复合材料制备室温自愈、坚固的超疏水涂层

Endowing superhydrophobic surfaces (SHS) with self-healing capability has been considered a promising approach to prolonging the lifespan of SHS. However, the reported SHS consisted of self-healing polymers and adhesive nanoparticles are still subject to the contradictions between robustness and complicated repairing conditions. In this work, a room-temperature self-healable, robust superhydrophobic coating was fabricated by combining dual cross-linking supramolecular silicone polymer (BPDI), which contains multiple hydrogen interactions and reversible nitrogen-coordinated boroxines, and SiO2 nanoparticles via facile spraying methods. Benefiting from the synergetic dual reversible bonds and high mobility of BPDI polymer chains, the supramolecular resin exhibits excellent self-healing ability, recyclability, and high adhesive strength to the substrates. After the incorporation of SiO2 nanoparticles, the surface of composite coatings revealed lotus-leaf-like morphology with an averaged roughness of 105 nm and superhydrophobicity with a WCA of 158.6°. More importantly, the obtained coatings could repair themselves spontaneously and repeatedly at room temperature via surface reorganization when the composites suffer chemical deterioration such as plasma etching. Furthermore, the coated surface can maintain superhydrophobicity even after being exposed to repeated mechanical or chemical damages, including sandpaper abrasion, solvent immersion, water dripping, and UV aging. The facts are reasonably attributed to the excellent stability of BPDI resins and robust interfacial adhesion with the substrate. Moreover, the prepared superhydrophobic composites with room-temperature self-healing capability and mechanochemical durability have been applied for self-cleaning and antifouling aspects on diverse substrates.

赋予超疏水表面(SHS)自愈能力被认为是延长SHS寿命的一种有前途的方法。然而，目前所报道的由自愈聚合物和黏附纳米颗粒组成的SHS仍然存在鲁棒性和复杂修复条件之间的矛盾。在这项工作中，通过简单的喷涂方法，将含有多个氢相互作用和可逆氮配位硼的双交联超分子有机硅聚合物(BPDI)与SiO2纳米颗粒结合，制备了一种室温自愈、坚固的超疏水涂层。得益于BPDI聚合物链的协同双可逆键和高迁移率，该超分子树脂具有优异的自愈能力、可回收性和对基体的高粘附强度。在SiO2纳米颗粒的掺入下，复合涂层表面呈现出荷叶状形貌，平均粗糙度为105 nm，超疏水性为158.6°。更重要的是，当复合材料遭受化学腐蚀(如等离子体蚀刻)时，所获得的涂层可以在室温下通过表面重组自发地重复修复。此外，涂层表面即使受到反复的机械或化学损伤，包括砂纸磨损、溶剂浸泡、滴水和紫外线老化，也能保持超疏水性。这些事实合理地归因于BPDI树脂优异的稳定性和与基材的强大界面附着力。此外，制备的超疏水复合材料具有室温自修复能力和机械化学耐久性，已在各种基材上应用于自清洁和防污方面。

A robust anti-icing/de-icing and self-healing coating based on efficient photothermal Bi2S3/Ti3C2Tx nanofillers

Cuiting Du, Wei Wang, Zihao Guo, Peng Wang, Shougang Chen

doi:10.1016/j.compositesb.2024.111255

基于高效光热 Bi2S3/Ti3C2Tx 纳米填料的坚固防冰/除冰和自愈涂层

The accumulation of ice can lead to various hazards, and currently, there is no suitable coating that can adapt to the low-temperature marine environment, providing anti-icing/de-icing and corrosion-resistant protection for metal surfaces. Here, we propose a multifunctional coating (BSPU) with Bi2S3/Ti3C2Tx as a photothermal filler and polyurethane (PU) as the matrix. Bi2S3/Ti3C2Tx exhibits a photothermal conversion efficiency of 76.13 % and excellent photothermal cycle stability. The PU matrix is composed of polydimethylsiloxane (PDMS), isophorone diisocyanate (IPDI), and Diels–Alder reaction (DA reaction) monomers, providing a smooth, hydrophobic, and self-healing surface. The BSPU coating achieves passive anti-icing and active de-icing performance. Bi2S3/Ti3C2Tx undergoes photothermal conversion to elevate the coating temperature, causing the ice layer to slip off within 300 s at −30 °C. BSPU extends the freezing time of water droplets under illumination to over 1500 s, 6.3 times longer than the freezing time on bare metal substrates. The corrosion resistance of the coating is significantly enhanced due to the "maze effect" provided by the two-dimensional filler. After soaking in a low-temperature environment for 90 d, |Z|0.01 Hz remains around 109 Ω cm2.The heat generated by Bi2S3/Ti3C2Tx promotes the occurrence of DA reversible reactions, enabling the damaged coating to self-heal within 300 s under 808nm laser irradiation. This work addresses the requirements of hydrophobicity and photothermal-dominated passive anti-icing/active de-icing and corrosion resistance, making it highly promising for applications in low-temperature marine environments.

冰的积累会导致各种危害，而目前还没有一种合适的涂料能够适应低温海洋环境，为金属表面提供防冰/除冰和防腐蚀保护。在此，我们提出了一种以 Bi2S3/Ti3C2Tx 为光热填料、聚氨酯（PU）为基体的多功能涂层（BSPU）。Bi2S3/Ti3C2Tx 的光热转换效率高达 76.13 %，且光热循环稳定性极佳。聚氨酯基体由聚二甲基硅氧烷（PDMS）、异佛尔酮二异氰酸酯（IPDI）和 Diels-Alder 反应（DA 反应）单体组成，具有光滑、疏水和自修复表面。BSPU 涂层具有被动防冰和主动除冰性能。Bi2S3/Ti3C2Tx 通过光热转换来提高涂层温度，从而使冰层在零下 30 °C、300 秒内滑落。BSPU 可将水滴在光照下的冻结时间延长至 1500 秒以上，是裸金属基底冻结时间的 6.3 倍。由于二维填料提供的 "迷宫效应"，涂层的耐腐蚀性能显著增强。在低温环境中浸泡 90 d 后，|Z|0.01 Hz 仍保持在 109 Ω cm2 左右。Bi2S3/Ti3C2Tx 产生的热量促进了 DA 可逆反应的发生，使受损涂层在 808nm 激光照射下可在 300 秒内自我修复。这项工作满足了疏水性和光热主导的被动防冰/主动除冰和耐腐蚀性的要求，使其在低温海洋环境中的应用前景十分广阔。

Phosphorus-containing curing agents with dynamic bonds endowing epoxy resins with flame retardancy and remolding capability

Xiaohui Liu, Haojie Wang, Birong Zeng, Xindan Yi, Weiang Luo, Guorong Chen, Yiting Xu, Conghui Yuan, Lizong Dai

doi:10.1016/j.compositesb.2024.111260

具有动态键的含磷固化剂，使环氧树脂具有阻燃性和重塑能力

To prepare epoxy resins (EP) with flame retardancy and remolding capability, novel amine curing agents (DDPM and DDPS), which incorporate phosphonates and bis-Schiff bases, were used to replace DDM partially or completely for EP curing. Curing kinetics based on a dual-parameter autocatalytic model showed that DDPM and DDPS had higher reactivity of than DDM. EP/DDPM and EP/DDPS vitrimers demonstrated excellnt flame retardancy and remolding capability (up to 60.8 %). EP/DDPS with disulfide bonds could not effectively improve the dynamic bond exchange. The molecular weight, dynamic bond stability, and viscosity were analyzed to investigate the underlying mechanisms. This study endows the dynamic properties of EP using novel curing agents and achieves flame-retardant and sustainable epoxy thermosets.

为了制备具有阻燃和重塑性能的环氧树脂(EP)，采用含膦酸盐和双希夫碱的新型胺类固化剂(DDPM和DDPS)部分或完全取代DDM固化EP。基于双参数自催化模型的固化动力学表明，DDPM和DDPS比DDM具有更高的反应活性。EP/DDPM和EP/DDPS聚合物表现出优异的阻燃性和重塑能力(高达60.8 %)。带二硫键的EP/DDPS不能有效改善动态键交换。对其分子量、动态键稳定性和粘度进行了分析，探讨了其机理。本研究利用新型固化剂赋予EP动态性能，实现了阻燃、可持续的环氧热固性材料。

Composites Science and Technology

MOF decorated boron nitride/natural rubber composites with heterostructure for thermal management application through dual passive cooling modes base on the improved thermal conductivity and water sorption-desorption process

Dong An, Hongfeng Chen, Rizheng He, Jiaqi Chen, Chunlei Liu, Zhijian Sun, Huitao Yu, Yaqing Liu, Chingping Wong, Wei Feng

doi:10.1016/j.compscitech.2024.110469

MOF修饰的异质结构氮化硼/天然橡胶复合材料通过提高导热性和水吸附-解吸双重被动冷却模式进行热管理应用

Numerous researches have drawn on the polymer-based thermal conductive composites to cope with heat dissipation issue both in the integrated electronics and human body. However, the limited thermal conductivity and mono-cooling mode even in the high filler content are always restricted its further application. Currently, the use of latent heat from phase transition has aroused researchers’ appetite for the thermal management. Herein, inspired by the sweat modulating the body temperature, a passive dual thermal management strategy was proposed by taking advantage of high latent heat and the improved thermal conductivity, where the liquid-vapor phase transition of water inside the MOF coated on the polymer-based composites to form the heterogeneous composites. In the proof-of-concept test, the obtained MIL-101 (Cr) MOF as the sorbent owned the high specific surface area of 1850 cm3/g, cyclic water uptake of 1.18 g and phase change enthalpy of 1780 J/g, which promoted the well spontaneous adsorption and desorption ability of water. While sulfur surface modified boron nitride/natural rubber composites (BN-S/NR) exhibited the excellent anisotropic thermal conductivity (11.48 W m−1 K−1) in the through-plane direction at the filler loading of 70 wt%. After the MIL-101 (Cr) MOF coated composites (MOF-BN-S/NR) with heterogeneous structure, the composites with 0.07 g MOF possessed the pretty cooling performance and thermal stability to adjust temperature at a proper range both in electronics and human body because of the dual passive heat dissipation approach. Therefore, these findings provide the meaningful insight into research to fabricate composites with heterogeneous-assisted heat dissipation in thermal management.

聚合物基导热复合材料在解决集成电子和人体散热问题方面得到了广泛的研究。然而，即使在高填料含量的情况下，有限的导热性和单一的冷却方式一直制约着它的进一步应用。目前，相变潜热的利用已经引起了热管理研究人员的兴趣。受汗液调节体温的启发，提出了一种被动双热管理策略，利用高潜热和提高导热性的优势，将MOF内部的水的液-气相转变包覆在聚合物基复合材料上，形成非均相复合材料。在概念验证试验中，得到的MIL-101 (Cr) MOF作为吸附剂具有1850 cm3/g的高比表面积，1.18 g的循环吸水性和1780 J/g的相变焓，促进了水的良好自发吸附和解吸能力。而硫表面改性氮化硼/天然橡胶复合材料(BN-S/NR)在填充量为70 wt%时，在通面方向上表现出良好的各向异性导热系数(11.48 W m−1 K−1)。在MIL-101 (Cr) MOF涂层复合材料(MOF- bn - s /NR)具有非均相结构之后，0.07 g MOF涂层复合材料由于采用双被动散热方式，具有良好的冷却性能和热稳定性，可在电子和人体中调节温度。因此，这些发现为研究在热管理中制造具有非均质辅助散热的复合材料提供了有意义的见解。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年1月1日固体力学SCI期刊最新文章

今日更新：Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇，Thin-Walled Structures 1 篇Mechanics of MaterialsEffect of the sonic shock wave on void evolution in materials under irradiationNing Zhou, YinBo Zhu, HengAn Wudoi:10.1016/j.mechmat.2023.104907 声波冲击波对辐照下材料空隙演变的影响Understanding the void-cascade interaction is of great importance for clarifying the irradiation damage as a major challenge in nuclear industry, since it typically causes void annihilation or shrinkage, which greatly affects the swelling of irradiated materials. But the current understanding of it is extremely limited due to the neglect of the sonic shock wave. Herein, we take γ-U as the representative model due to the emergence of a violent sonic shock wave there. Molecular dynamics simulations are performed to explore the underlying mechanism of the sonic shock wave interacting with voids. It is firstly revealed that the sonic shock wave is essentially focusons along <111> crystal orientation family, attributed to the highest energy transfer efficiency along <111> in γ-U. These focusons can cause void annihilation or shrinkage via sliding, while thermal spikes only cause annihilation by covering voids. Combining these two factors, we propose a model to qualitatively epitomize the void-cascade interaction, in which the influence scope exhibits an intriguing anisotropic feature, overturning a long-accepted view that the void-cascade interaction is isotropic. This model is further generalized to other nuclear materials owing to the similar mechanism of the sonic shock wave. Moreover, we find distinct size effect of voids on void-cascade interaction. Thermal spikes hardly affect voids that are too large to be covered, while the sonic shock wave also causes visible shrinkage in large voids. The present work proves that the sonic shock wave has a non-negligible effect on void evolution, improving the fundamental understanding of void-cascade interaction in irradiated materials.空隙-级联相互作用通常会导致空隙湮灭或收缩，从而极大地影响辐照材料的膨胀，因此了解空隙-级联相互作用对于澄清辐照损伤这一核工业领域的重大挑战具有重要意义。但由于忽视了声波冲击波，目前对它的认识极为有限。在此，我们以γ-U 为代表模型，因为那里出现了剧烈的声波冲击波。通过分子动力学模拟来探索声波冲击波与空隙相互作用的内在机理。研究首先揭示了声波冲击波本质上是沿 <111> 晶向系列的焦子，这归因于在 γ-U 中沿 <111> 晶向的能量传递效率最高。这些聚焦子可以通过滑动造成空隙湮灭或收缩，而热尖峰只能通过覆盖空隙造成湮灭。结合这两个因素，我们提出了一个模型来定性地表征空隙-级联相互作用，其中的影响范围呈现出令人感兴趣的各向异性特征，推翻了长期以来公认的空隙-级联相互作用各向同性的观点。由于音速冲击波的机制类似，这一模型还可进一步推广到其他核材料。此外，我们还发现空隙的大小对空隙-级联相互作用有明显的影响。热尖峰几乎不会影响大到无法覆盖的空隙，而声波冲击波也会导致大空隙的明显收缩。本研究证明了声波冲击波对空隙演变具有不可忽视的影响，从而提高了对辐照材料中空隙-级联相互作用的基本认识。International Journal of PlasticityAchieving exceptional work-hardening capability of additively-manufactured multiphase Fe-Mn alloys via multiple deformation mechanismsPeifeng Liu, Qinyuan Huang, Quan Shan, Zengbao Jiao, Qingge Wang, Yang Ma, Runhua Zhou, Ian Baker, Hong Wudoi:10.1016/j.ijplas.2023.103871 通过多种变形机制实现快速成型多相铁-锰合金的超强加工硬化能力Laser-powder-bed-fusion (LPBF) fabricated Fe-Mn biodegradable alloys provide an attractive prospect for orthopedic applications due to their good tensile strength and high degradation rate. Nevertheless, the ε-martensite and heterogeneous microstructures produced by the LPBF processing often lead to premature failure of alloys. Herein, we report a LPBFed multiphase Fe-18Mn alloy (γ-austenite, ε-martensite, and α-ferrite) fabricated from pre-alloyed powders. After annealing at 650 °C, the alloy with a uniform microstructure displays a high 1 GPa tensile strength, a good fracture elongation of 16 %, and an extremely high work-hardening rate of 8500 MPa. The work-hardening rate is higher than that reported in most Fe-Mn steels and Fe-based high entropy alloys. The grain size of a few hundred nanometers provided the excess Gibbs free energy, resulting in an increase in the stacking fault energy (SFE) to 23.9 mJ/m2. The multiple deformation mechanisms, i.e., SFs, the martensitic transformation (γ → ε → α') and nano-deformation twins (DTs), were sequentially activated. We elucidate such unique work-hardening capability, originating from the interaction between the DTs, SFs and transformed martensite. Besides a high-density of dislocations were accumulated between parallel planar defects, the cooperative deformation of the soft and hard phases provided continuous hardening. Our findings highlight the exceptional work-hardening capability of additively-manufactured Fe-Mn alloys achieved by a multiphase material exhibiting multiple deformation mechanisms. The work also provides a straightforward approach for the development of stable-implanted Fe-based bone substitutes.激光粉末床熔融（LPBF）制造的铁锰生物可降解合金具有良好的抗拉强度和较高的降解率，为矫形外科应用提供了诱人的前景。然而，LPBF加工过程中产生的ε-马氏体和异质微结构往往会导致合金过早失效。在此，我们报告了一种由预合金化粉末制成的 LPBFed 多相铁-18Mn 合金（γ-奥氏体、ε-马氏体和 α-铁素体）。在 650 °C 退火后，具有均匀微观结构的合金显示出较高的 1 GPa 抗拉强度、16 % 的良好断裂伸长率和 8500 MPa 的极高加工硬化率。该加工硬化率高于大多数铁锰钢和铁基高熵合金的加工硬化率。几百纳米的晶粒尺寸提供了过剩的吉布斯自由能，导致堆叠断层能（SFE）增加到 23.9 mJ/m2。多种变形机制，即 SFs、马氏体转变（γ → ε → α'）和纳米变形孪晶（DTs）依次被激活。我们阐明了这种独特的加工硬化能力，它源于 DTs、SFs 和转化马氏体之间的相互作用。除了在平行平面缺陷之间积累了高密度位错之外，软硬相的协同变形还提供了持续硬化。我们的研究结果凸显了加成法制造的铁锰合金通过表现出多种变形机制的多相材料实现的卓越加工硬化能力。这项研究还为开发稳定的植入式铁基骨替代物提供了一种直接的方法。Distinct avalanche dynamics detected in metallic glasses with high energy state revealing the crack-like shear banding mechanismKai Tao, Fucheng Li, Yanhui Liu, Eloi Pineda, Kaikai Song, Jichao Qiaodoi:10.1016/j.ijplas.2023.103873在金属玻璃中探测到的高能态雪崩动力学揭示了类似裂纹的剪切带机制When a sufficiently high stress is applied to a metallic glass, causing plastic deformation, the material undergoes structural reconfiguration through dissipative slip avalanche events that release local stresses. By utilizing isothermal annealing and cold rolling techniques to tune the energy levels of metallic glasses, it has been observed that structural rejuvenation is accompanied by structural relaxation, as evidenced by distinct changes in avalanche dynamics. We present detailed statistics of the avalanche dynamics during shear band formation in energy-tuned metallic glasses, ranging from structurally relaxed to rejuvenated states. By analyzing shear band characteristics and examining scaling exponents, avalanche durations, and stress relaxation rates, we can establish a connection between the local activation of shear transformation zones and the formation of macroscopic shear bands. The statistics of avalanche duration indicate that an increase in soft zones within metallic glasses can alleviate stress release and stabilize plastic flow, as evidenced by the characteristics of shear bands. We attribute the significant transition of serrated flow, observed at different energy levels (i.e., as-cast, relaxed, and rejuvenated states) to the variations in nucleation and multiplication of shear bands that originate from local weak spots. Analysis of the distinct avalanche dynamics suggests that in lower energy level metallic glasses, the nucleation and propagation of shear bands exhibit localized crack-like behavior, while in higher energy level metallic glasses, they display diffused crack-like characteristics. Indeed, our results strongly support that the decreased avalanches observed in the high energy level metallic glasses originate from the nucleation of numerous small shear bands, which directly compete with the propagation of the main local shear band. These findings deepen our fundamental understanding of the relationship between the microscopic mechanism of slip avalanche dynamics and shear banding, providing a pathway to control the plasticity of metallic glasses.当对金属玻璃施加足够大的应力导致塑性变形时，材料会通过释放局部应力的耗散滑移雪崩事件进行结构重构。通过利用等温退火和冷轧技术调节金属玻璃的能级，我们观察到结构年轻化伴随着结构松弛，雪崩动力学的明显变化就是证明。我们介绍了能量调谐金属玻璃剪切带形成过程中雪崩动力学的详细统计数据，包括从结构松弛状态到年轻化状态。通过分析剪切带特征并研究缩放指数、雪崩持续时间和应力松弛率，我们可以建立剪切转换区局部激活与宏观剪切带形成之间的联系。雪崩持续时间的统计结果表明，金属玻璃内部软区的增加可以缓解应力释放并稳定塑性流动，剪切带的特征也证明了这一点。我们认为，在不同能级（即铸造态、松弛态和恢复态）下观察到的锯齿流的显著转变是由于局部薄弱点产生的剪切带的成核和增殖变化造成的。对不同雪崩动力学的分析表明，在低能级金属玻璃中，剪切带的成核和传播表现出局部裂纹状行为，而在高能级金属玻璃中，则表现出扩散裂纹状特征。事实上，我们的研究结果有力地证明，在高能级金属玻璃中观察到的雪崩现象的减少源于无数小剪切带的成核，这些剪切带与主要局部剪切带的传播直接竞争。这些发现加深了我们对滑动雪崩动力学微观机制与剪切带之间关系的基本理解，为控制金属玻璃的塑性提供了一条途径。Thin-Walled StructuresWave propagation in beams with functionally graded porosity distribution under highly transient axial and transverse impactsM. Heshmati, S.K. Jalali, N.M. Pugnodoi:10.1016/j.tws.2023.111548在高瞬态轴向和横向冲击下，具有功能分级孔隙分布的梁中的波传播Recent advances in the manufacturing process provide a possibility of fabricating a new generation of porous materials denoted by functionally graded porous materials (FGPM). This paper aims to present a time domain analysis of wave propagation through the porous structures with functionally graded porosity distribution, which has not been completely studied before. For this purpose, the beams with different functionally graded porosity distributions subjected to both axial and transverse tip impact loads with a high-frequency content are investigated. The shear deformable cantilevered functionally graded porous beams with various porosity distributions through the beam thickness are studied. The governing differential equations are derived using the Hamiltonian principle based on the Timoshenko beam theory. A locking-free first-order shear deformable beam element is used to derive the finite element formulation of the equations. The Newmark time integration method is used to perform a time domain analysis of the equations of motion and to investigate the transient response of the beams. The axial and transverse wave propagation characteristics through functionally graded (FG) porous beams are found using time domain analysis of the results. Deflection and velocity time histories of the tip and each point of the beam, reflection time, and variation of support reactions are obtained. The influences of the porosity magnitude and porosity distribution on the wave propagation characteristics and overall time responses are investigated. The results reveal that porosity distribution has a significant effect on the wave amplitude, wave speed, and reflection from the boundary. Also, this study can help in a better understanding of porous structures' behavior subjected to high-transient impact loads in different engineering applications.制造工艺的最新进展为制造新一代多孔材料提供了可能，这种材料被称为功能分级多孔材料（FGPM）。本文旨在对波在具有功能分级孔隙率分布的多孔结构中的传播进行时域分析，而这在以前还没有过完整的研究。为此，本文研究了具有不同功能分级孔隙率分布的横梁，这些横梁同时承受轴向和横向尖端高频冲击载荷。研究了在梁厚度上具有不同孔隙率分布的可剪切变形悬臂功能分级多孔梁。基于季莫申科梁理论，利用哈密顿原理推导出了控制微分方程。无锁定一阶剪切变形梁元素用于推导方程的有限元公式。采用纽马克时间积分法对运动方程进行时域分析，并研究梁的瞬态响应。通过对结果进行时域分析，发现了穿过功能分级（FG）多孔梁的轴向和横向波传播特性。得出了梁顶端和各点的挠度和速度时间历程、反射时间以及支撑反作用力的变化。研究了孔隙率大小和孔隙率分布对波传播特性和整体时间响应的影响。结果表明，孔隙率分布对波幅、波速和边界反射有显著影响。此外，这项研究还有助于更好地理解多孔结构在不同工程应用中承受高瞬态冲击载荷时的行为。来源：复合材料力学仿真Composites FEM