今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 4 篇,Composites Part B: Engineering 1 篇
Three-dimensional vibration analysis of multilayered composite and functionally graded piezoelectric plates and shells
S. Brischetto, D. Cesare
doi:10.1016/j.compstruct.2024.118413
多层复合材料和功能梯度压电板壳的三维振动分析
In the present paper, a coupled 3D exact electro-elastic shell model for Functionally Graded (FG) and composite piezoelectric structures is proposed. Primary variables of the electro-elastic model are the electric potential and the three displacement components. The model allows to evaluate the piezoelectric effect in terms of frequencies and vibration modes. Both closed and open circuit configurations are analyzed and compared. The 3D equilibrium equations and the 3D divergence electric displacement equation for spherical shells give the set of partial differential equations for the electro-elastic problem. The proposed model for spherical shells automatically degenerates into simpler models for plates and cylindrical shells via properly considerations on radii of curvature along in-plane directions. The orthogonal mixed curvilinear coordinates α, β and z are employed. The partial differential governing equations have constant coefficients considering fictitious layers and they are solved using the Navier harmonic form and the exponential matrix method. These features lead to an exact solution for simply-supported boundary conditions. Free vibration analyses are conducted and circular frequencies for the first three thickness vibration modes are computed. After a global assessment phase to verify the correctness of the developed model, new benchmarks are proposed: different thickness ratios and material configurations are investigated. The present work can be intended as a reference general solution for those scientists interested in the study of piezoelectric structures via 2D analytical and numerical formulations.
本文提出了功能梯度(FG)和复合压电结构的三维精确电弹性壳体耦合模型。电弹性模型的主要变量是电动势和三个位移分量。该模型可根据频率和振动模式评估压电效应。对闭路和开路配置进行了分析和比较。球壳的三维平衡方程和三维发散电位移方程给出了电弹性问题的偏微分方程组。通过适当考虑沿平面方向的曲率半径,所提出的球壳模型会自动退化为更简单的板壳和圆柱壳模型。模型采用了正交混合曲线坐标 α、β 和 z。考虑到虚构层,偏微分控制方程具有常数系数,并采用纳维谐波形式和指数矩阵法求解。这些特点导致了对简单支撑边界条件的精确求解。进行了自由振动分析,并计算了前三个厚度振动模式的圆周频率。经过全面评估阶段以验证所开发模型的正确性后,提出了新的基准:研究了不同的厚度比和材料配置。本研究成果可作为一般参考解决方案,供对通过二维分析和数值公式研究压电结构感兴趣的科学家参考。
Ultra-high temperature brazing of C/C using a simplified FeNiCrCu high-entropy alloy as filler
Xin Jiang, Guifeng Zhang, Kaiming Wang, Peng He
doi:10.1016/j.compositesa.2024.108370
采用简化FeNiCrCu高熵合金作为钎料进行C/C超高温钎焊
To increase remelting temperature of C/C brazed joint, a simplified FeNiCrCu high-entropy alloy (HEA) filler was designed in high-temperature brazing (HTB). The joint formation mechanism and fracture behavior were studied. The eutectic reaction of FeNiCrCu HEA with C/C could not occur, helping increase joint remelting temperature over HEA melting point (1334 °C). For the recommended parameter 1350 °C-2 min, C/C dissolution occurred well, and no defect was observed both at interface and within bond seam. The maximum shear strength was 24.2 MPa due to the high strength in-situ (Cr,Fe)3C2 reinforced the high plastic Cu-Ni-Fe(S.S.) matrix and intimate wavy interface. Cr existed only in M3C2 in bond seam, reducing both carbon content and CTE of bond seam. For higher temperature and longer time, excessive liquid carbon content resulted in the presence of large solidified carbon with defect at interface, joint shear strength decreased dramatically. These results provide a unique braze system for brazing carbon-based materials.
为了提高C/C钎焊接头的重熔温度,设计了一种简化的FeNiCrCu高熵合金(HEA)钎料用于高温钎焊(HTB)。研究了接头的形成机理和断裂行为。FeNiCrCu HEA与C/C的共晶反应不能发生,有助于提高接头重熔温度超过HEA熔点(1334 °C)。当推荐参数为1350 °C-2 min时,C/C溶解良好,界面和粘结缝内均未出现缺陷。高强度原位(Cr,Fe)3C2增强了高塑性Cu-Ni-Fe(S.S.)基体和紧密波状界面,最大抗剪强度为24.2 MPa。Cr仅存在于粘结缝的M3C2中,降低了粘结缝的含碳量和CTE。温度越高、时间越长,液态碳含量过高导致界面处存在较大的凝固碳缺陷,节理抗剪强度急剧下降。这些结果为钎焊碳基材料提供了一个独特的钎焊系统。
Design of polyimide/carbon nanotube@Ag@polyimide/graphene composite aerogel for infrared stealth and electromagnetic interference protection
Wuxuan Zheng, Hai Xie, Jinmei Li, Hao Yu, Zhangzhang Tang, Guangke Tian, Qihua Wang, Tingmei Wang
doi:10.1016/j.compositesa.2024.108371
聚酰亚胺/碳nanotube@Ag@聚酰亚胺/石墨烯复合气凝胶的红外隐身和电磁干扰防护设计
CHATGPT artificial intelligence is taking the world by storm, and countless electronic devices will generate massive amounts of electromagnetic interference (EMI). Hence, there is a pressing demand for materials exhibiting high thermal conductivity and superior EMI shielding effectiveness (SE). Thus, we construct a polyimide/carbon nanotube@Ag@polyimide/graphene (PCAPG) composite aerogel with porous, layered, and homogeneous structures in one, which provides a new idea for the multi-interface polarization interaction and special structure of anti-EMI materials. PCAPG has high thermal conductivity of ∼ 0.259 W (mK)-1 at 25 °C, excellent EMI SE of ∼ 90.28 dB and specific shielding effectiveness (SSE) of ∼ 940.42 dB cm3 g−1. The synergistic EMI attenuation mechanism of the PCAPG composite structure is analyzed using an aerogel unit. This composite aerogel provides a viable solution for infrared stealth, promoting heat dissipation from electronic components and reducing electromagnetic interference.
人工智能正在席卷全球,无数的电子设备将产生大量的电磁干扰(EMI)。因此,对具有高导热性和优异的电磁干扰屏蔽效能(SE)的材料有迫切的需求。因此,我们构建了一种集多孔、层状和均相结构于一体的聚酰亚胺/碳nanotube@Ag@聚酰亚胺/石墨烯(PCAPG)复合气凝胶,为抗电磁干扰材料的多界面极化相互作用和特殊结构提供了新的思路。PCAPG具有较高的热导率的 ∼ 25 0.259 W(可)1°C,优秀EMI SE ∼ 90.28 dB和具体的屏蔽效能(SSE)的 ∼ 940.42 dB立方厘米克−1。利用气凝胶装置分析了PCAPG复合结构的协同EMI衰减机理。这种复合气凝胶为红外隐身提供了可行的解决方案,促进了电子元件的散热,减少了电磁干扰。
Multifunctional, efficient, and durable composites of conductive PMIA/Ag membrane
Bai Jiang, Jianxun Shang, Faying Zhang, Na Li, Yan Wang, Zuming Hu, Junrong Yu
doi:10.1016/j.compositesa.2024.108372
多功能、高效、耐用的导电PMIA/Ag膜复合材料
Developing high-efficiency electromagnetic interference (EMI) shielding composite membranes along with additional functionalities to extend the application scenarios is highly desirable for the next generation electronic devices. Here, we report an ultrathin and flexible EMI shielding materials with sensitive Joule heating and outstanding infrared stealth performance was fabricated from poly-m-phenylene isophthalamide (PMIA) and Ag nanoparticles (AgNPs) through an innovation and simplicity method of electrospinning and electroless plating. Profiting from a continuous three-dimensional (3D) conductive network, the final membrane achieves an outstanding EMI shielding effectiveness (SE) of 100.51 dB (in X-band), a remarkable Joule heating properties with a fast thermal response and low driving voltage (<0.5V), and an outstanding infrared stealth with a low infrared emissivity (0.28). Meanwhile, the prepared composite membrane demonstrates stable EMI SE even after water washing, continuous bending, and heating treatment. This work integrates high-performance fiber PMIA, characterized by high heat resistance, flame retardancy, self-extinguishing properties, and chemical resistance, with functions such as EMI shielding, infrared stealth, and autonomous thermal management. It has great development potential if utilized in specialized combat uniforms under harsh conditions.
开发高效电磁干扰(EMI)屏蔽复合膜以及扩展应用场景的附加功能是下一代电子设备非常需要的。在这里,我们报道了一种超薄的柔性电磁干扰屏蔽材料,具有灵敏的焦耳加热和出色的红外隐身性能,由聚-间苯二胺(PMIA)和银纳米粒子(AgNPs)通过静电纺丝和化学镀的创新和简单的方法。得益于连续的三维(3D)导电网络,最终膜实现了100.51 dB (x波段)的出色EMI屏蔽效率(SE),具有快速热响应和低驱动电压(<0.5V)的卓越焦耳加热性能,以及具有低红外发射率(0.28)的出色红外隐身性能。同时,制备的复合膜在水洗、连续弯曲和加热处理后仍具有稳定的EMI SE。本工作集成了高性能PMIA纤维,具有高耐热性、阻燃性、自熄性和耐化学性,具有EMI屏蔽、红外隐身和自主热管理等功能。如果在恶劣条件下的特种作战制服中使用,具有很大的发展潜力。
Dynamically Crosslinked ECM-like Hydrogels Loaded with ROS-responsive Drug Nanoparticles for Treating Inflammation in Myocardial Infarction and Stroke
Zhicun Wang, Cheng Hu, Wen Zhang, Wenqi Liu, Shuyi He, Yang Liu, Li Yang, Yunbing Wang
doi:10.1016/j.compositesb.2024.111734
动态交联载ros反应药物纳米颗粒的类ecm水凝胶用于治疗心肌梗死和中风的炎症
Following a myocardial infarction (MI) or stroke, the excessive generation of reactive oxygen species (ROS) within a breaf timeframe may induce a pronounced inflammatory reaction, which exacerbates the progression of the disease. Thus, there is an urgent need to design a biomaterial to inhibit the inflammatory response associated with MI and stroke. In this study, we designed a reversible extracellular matrix (ECM)-like hydrogel via borate ester crosslinking, which responds to the inflammatory microenvironment affected by MI and stroke. At the same time, we developed a new type of loaded polymer nanoparticle (TK-DA) that can respond to ROS in ischemic regions and release the antiinflammatory drug dexamethasone. Ultimately, we integrated the nanoparticles and ECM-like hydrogel to fabricate a functional hydrogels.To verify the therapeutic effect of the functional hydrogel, we established two models of typical ischemic diseases, MI and stroke. The results showed that the hydrogel substantially reduced ROS levels and inflammation in vitro. Moreover, the results of the two in vivo animal models demonstrated that this functional hydrogel can effectively treat MI and stroke by suppressing inflammatory responses, mitigating apoptosis, and promoting neovascularization. In conclusion, the functional hydrogel strategy presents a universally applicable treatment approach for ischemic cardiovascular and cerebrovascular diseases, which are not limitted solely to the treatment of MI and stroke, but also hold future potential for clinical applications.
心肌梗死(MI)或中风后,呼吸时间内活性氧(ROS)的过量产生可能诱发明显的炎症反应,从而加剧疾病的进展。因此,迫切需要设计一种生物材料来抑制心肌梗死和脑卒中相关的炎症反应。在这项研究中,我们通过硼酸酯交联设计了一种可逆的细胞外基质(ECM)样水凝胶,该水凝胶对心肌梗死和中风影响的炎症微环境做出反应。同时,我们开发了一种新型负载聚合物纳米颗粒(TK-DA),它可以响应缺血区域的ROS并释放抗炎药物地塞 米松。最终,我们将纳米颗粒与类ecm水凝胶结合,制成功能性水凝胶。为了验证功能性水凝胶的治疗效果,我们建立了心肌梗死和脑卒中两种典型缺血性疾病模型。结果表明,水凝胶在体外显著降低ROS水平和炎症。此外,两种体内动物模型的结果表明,该功能性水凝胶可以通过抑制炎症反应、减轻细胞凋亡和促进新生血管形成来有效治疗心肌梗死和脑卒中。综上所述,功能性水凝胶策略是一种普遍适用于缺血性心脑血管疾病的治疗方法,它不仅局限于心肌梗死和脑卒中的治疗,而且具有未来临床应用的潜力。