Editorial: Special subject on the mechanical behavior of thermal protection materials and structures

The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.

Establishment and Optimization of Ablation Surrogate Model for Thermal Protection Material

The temperature response calculation of thermal protection materials,especially ablative thermal protection materials,usually adopts the ablation model,which is complicated in process and requires a large amount of calculation.Especially in the process of optimization calculation and parameter identification,the ablation model needs to be called many times,so it is necessary to construct an ablation surrogate model to improve the computational efficiency under the premise of ensuring the accuracy.In this paper,the Gaussian process model method is used to construct a thermal protection material ablation surrogate model,and the prediction accuracy of the surrogate model is improved through optimization.

Effect of Phase Change Materials on the Thermal Protective Performance of the Multi-layered Fabrics Examined by TPP Tester under Flash Fire

Cotton fabrics treated with phase change materials( PCMs)were used in multi-layered fabrics of the fire fighter protective clothing to study its effect on thermal protection. The thermal protective performance( TPP) of the multi-layered fabrics was measured by a TPP tester under flash fire. Results showed that the utilization of the PCM fabrics improved the thermal protective performance of the multi-layered fabrics. The fabric with a PCM add on of 41. 9% increased the thermal protection by 50. 6% and reduced the time to reach a second degree burn by 8. 4 s compared with the reference fabrics( without PCMs). The employment of the PCM fabrics also reduced the blackened areas on the inner layers. The PCM fabrics with higher PCM melting temperature could bring higher thermal protective performance.

Thermally insulating and fire-retardant bio-mimic structural composites with a negative Poisson's ratio for battery protection

Battery safety has attracted considerable attention worldwide due to the rapid development of wearable electronics and the steady increase in the production and use of electric vehicles.As battery failures are often associated with mechanical-thermal coupled behaviors,protective shielding materials with excellent mechanical robustness and flame-retardant properties are highly desired to mitigate thermal runaway.However,most of the thermal insulating materials are not strong enough to protect batteries from mechanical abuse,which is one of the most critical scenarios with catastrophic consequences.Here,inspired by wood,we have developed an effective approach to engineer a hierarchical nanocomposite via self-assembly of calcium silicate hydrate and polyvinyl alcohol polymer chains(referred as CSH wood).The versatile protective material CSH wood demonstrates an unprecedented combination of light weight(0.018 g cm-3),high stiffness(204 MPa in the axial direction),negative Poisson's ratio(-0.15),remarkable toughness(6.67×105 J m-3),superior thermal insulation(0.0204 W m-1 K-1 in the radial direction),and excellent fire retardancy(UL94-V0).When applied as a protective cover or a protective layer within battery packages,the tough CSH wood can resist high-impact load and block heat diffusion to block or delay the spread of fire,therefore significantly reducing the risk of property damage or bodily injuries caused by battery explosions.This work provides new pathways for fabricating advanced thermal insulating materials with large scalability and demonstrates great potential for the protection of electronic devices.

Thermal Investigation for Solid Rocket Motor Nozzle Inserts Material

A time-resolved numerical computational approach, involving the combustion of double-base propellant is performed on thermal protection material for SRM nozzle. An implicit Navier-Stokes Solver is selected to simulate two-dimensional axial-symmetric unsteady turbulent flow of compressible fluid. The governing equations are discredited by using the finite Volume method. S-A turbulence model is employed. CFD scheme is implemented to investigate the temperature distribution causes at nozzle throat inserts composite material. Different parameters have been selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle. The advanced SRM nozzle composite material is also characterized for the high thermo stability and high thermo mechanical capabilities to make it more reliable, simpler and lighter.

A new surface catalytic model for silica-based thermal protection material for hypersonic vehicles

Silica-based materials are widely employed in the thermal protection system for hypersonic vehicles, and the investigation of their catalytic characteristics is crucially important for accurate aerothermal heating prediction. By analyzing the disadvantages of Norman＇s high and low temperature models, this paper combines the two models and proposes an eight-reaction combined surface catalytic model to describe the catalysis between oxygen and silica surface. Given proper evaluation of the parameters according to many references, the recombination coefficient obtained shows good agreement with experimental data. The catalytic mechanisms between oxygen and silica surface are then analyzed. Results show that with the increase of the wall temperature, the dominant reaction contributing to catalytic coefficient varies from Langmuir Hinshelwood （LH） recombination （Tw 〈 620 K） to Eley Rideal （ER） replacement （620 K 〈 Tw 〈 1350 K）, and then to 02 desorption （Tw 〉 1350 K）. The surface coverage of chemisorption areas varies evidently with the dominant reactions in the high temperature （HT） range, while the surface coverage of physisorption areas varies within quite low temperature （LT） range （Tw 〈 250 K）. Recommended evaluation of partial parameters is also given.

Multi-phase flow effect on SRM nozzle flow field and thermal protection materials

Multi-phase flow effect generated from the combustion of aluminum based composite propellant was performed on the thermal protection material of solid rocket motor(SRM) nozzle.Injection of alumina(Al2O3) particles from 5% to 10% was tried on SRM nozzle flow field to see the influence of multiphase flow on heat transfer computations.A coupled,time resolved CFD(computational fluid dynamics) approach was adopted to solve the conjugate problem of multi-phase fluid flow and heat transfer in the solid rocket motor nozzle.The governing equations are discretized by using the finite volume method.Spalart-Allmaras(S-A) turbulence model was employed.The computation was executed on the different models selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle.Comparison for temperatures variations were also carried out at different expansion ratios of nozzle.This paper also characterized the advanced SRM nozzle composites material for their high thermo stability and their high thermo mechanical capabilities to make it more reliable simpler and lighter.

Porous carbon-based thermally conductive materials:Fabrication,functions and applications

The demand for electronic devices has dramatically increased in the past few years.Efficient electronic devices require excellent thermal management systems to extend their operation time and prevent heat accumulation from affecting performance.Carbonaceous materials are considered as one of the ideal thermal management materials due to their excellent physiochemical stability.In addition,since porous-structured carbon materials typically exhibit outstanding thermal conductivity,low density,and large contact area,they have attracted considerable attention from both academia and industry in the last decades.In this review,methods and strategies for the preparation of highly thermally conductive porous carbon-based materials and the factors that influence their thermal conductivity of the materials are summarized.The thermal performance of porous carbonaceous materials fabricated by different approaches and their applications are also discussed.Finally,the potential challenges and strategies for the development and applications of highly thermally conductive porous carbona-ceous materials are discussed.

Directional mechanical and thermal properties of single-layer black phosphorus by classical molecular dynamics

Black phosphorus （BP） has received attention due to its own higher carrier mobility and layer dependent electronic properties, such as direct band gap. Interestingly, the single layer black phosphorus （SLBP） has had large popularity in applications related to thermoelectric, optoelectronic, and electronic devices. Here, we investigate the phonon spectrum, thermal conductivities, and stress strain effects. Robust anisotropy was mainly observed in the thermal conductivities together with the alongside zigzag （ZZ） direction value, compared to the armchair （AC） directions. We also investigated the attitude of stress that was anisotropic in both directions, and the stress effects were two times greater across the ZZ path than those in the AC direction at a low temperature. We obtained a ~oung＇s modulus of 63.77 and 20.74 GPa in the AC and ZZ directions, respectively, for a strain range of 0.01. These results had good agreement with first principle calculations. Our study here is useful and significant for the thermal tuning of phosphorus-based nanoelectronics and thermalelectric applications of phosphorus.

可重复使用热防护材料研究进展

具有轻量化、耐高温、高抗损伤、重复使用、易于维护等性能的热防护材料是空天往返飞行器的关键材料,影响飞行器的先进性、可靠性、维护性和经济性。本文针对可重复使用飞行器机身大面积、头锥、翼前缘以及控制面等部位所需的热防护材料,综述了刚性隔热瓦、柔性隔热毡、抗氧化C/C、C/SiC、TUFROC等可重复使用热防护材料的发展历史、研究现状及在飞行器上的应用情况。总结了高温服役过程中典型热防护材料的损伤及性能衰减行为,并提出以材料损伤为基础,研究材料的可重复使用性能及寿命预测方法。最后,提出研制高性能可重复使用热防护材料、发展热防护材料可重复使用理论方法与标准、建立可重复使用热防护材料数据库是该领域今后需要重点关注的方向。

新型热防护材料研究进展

为分析热防护材料领域研究现状和未来发展趋势,文章采用信息可视化、网络分析的研究方法,以Web of Science(WOS)数据库及中国知网(CNKI)数据库中近30年(1993年1月—2023年6月)热防护材料相关的文献作为数据来源绘制可视化信息图谱,对发文量、发文国家地区和机构、研究方向、核心作者、关键词等元素逐一进行分析,剖析热防护材料研究领域的发展动态、研究热点及前沿趋势。结果显示,美国、中国为主要研究国家,在该领域居重要地位;LI J(Li Jun)、SONG G W(Song Guowen)、SU Y(Su Yun)、LU Y H(Lu Yehu)、王云仪、朱方龙等作者为该领域的核心作者,在热应激、热防护服的研究中具有重要影响力;热防护服的热防护性与传热机制、人体的热生理与热舒适为活跃的研究主题与研究热点;相变材料、气凝胶、形状记忆织物、蜂窝夹芯织物、三维间隔织物为当前的研究热点材料,新型热防护材料的研发、服装内部结构的优化是未来研究中有效应对热应激的解决方法,是兼顾热防护服的热防护与热舒适平衡的重要途径。

气凝胶复合材料在干式潜水服内胆隔热性能提升中的应用

为提升干式潜水服内胆的隔热性能,并探究气凝胶复合材料在潜水服内胆中的水下应用潜力。选择絮片型、发泡型及非织造布型气凝胶复合材料,采用绗缝工艺技术模拟材料在水下的受压状态,研究其在压缩状态下的隔热性能,然后,制作潜水服内胆,通过暖体假人实验及真人水下实验测试其隔热性能。结果表明,絮片型气凝胶复合材料的水下适用性优于絮片型新雪丽棉;发泡型及非织造布型气凝胶复合材料的热阻受压强影响小,也较适用于水下环境;在真人实验过程中,潜水员的核心温度始终大于37℃,证明所研制的气凝胶复合材料内胆具有良好的水下隔热效果。研究结果可为受压环境下防护服隔热材料的应用方法提供指导建议。

聚合物表面空间环境防护涂层热应力分析方法研究进展

柔性聚合物材料作为航天器表面用关键材料,易受到空间环境的协同损伤,在其表面制备防护涂层是实现长期服役的重要技术。但由于常用防护涂层与基体间的性能差异,涂层易因应力出现开裂和剥落,因此应力分析对于材料的设计和优化非常重要。对于涂层应力的分析方法,主要可以分为基于试验测量以及基于数值仿真的有限元分析方法两类。梳理目前常见的试验测量方法,分析有损法和无损法试验测量的应用,整理归纳基于数值仿真的有限元分析方法的原理以及相关应用,比较不同方法的优缺点,总结其局限性以及应用前景。不同应力测试分析方法在材料的服役寿命和失效形式预测中发挥了重要作用,但传统的机械有损测量方法难对应力情况进行实时监测,近年来发展起来的无损法也存在一定的应用局限性,有限元模拟具有实时、全面的应力测量优点,但是与实际涂层模型具有一定的差距。基于目前试验方法与有限元仿真各自的局限性,提出将有限元仿真与试验表征结合成为进一步指导涂层设计的有效方法,有望有效预测涂层失效机制,优化涂层材料制备工艺,开发具有低应力结构的涂层材料,为聚合物表面用关键涂层材料的轻量化发展和长期可靠服役提供技术支撑。

树脂基防隔热一体化热防护复合材料高温性能演变分析

采用溶胶-凝胶-常压干燥的方法,以耐热杂化酚醛树脂(PF)为基体,复合碳纤维编织物(CF)制备树脂基防隔热一体化热防护复合材料(PF/CF-HT01)。利用热分析(TG)、电子万能试验机研究材料热稳定性和高温力学性能,利用氧乙炔装置研究材料耐烧蚀性能,利用扫描电子显微镜(SEM)、X线衍射仪(XRD)研究材料微观结构演变过程。结果表明:空气中树脂基体的初始分解温度为387.3℃,最大分解温度为644.7℃,800℃时残炭率为13.8%;复合材料初始分解温度为405.3℃,800℃时残炭率为42.8%;复合材料常温压缩强度最大为542.6 MPa,经1 000℃原位热处理30和60 s后的最大压缩强度分别为166.2和149.9 MPa。复合材料具有良好的防隔热一体化性能,其线烧蚀率可达0.039 mm/s,单次热考核结束时背温低于100℃、继续热传导后最高背温低于200℃。高温作用下材料快速陶瓷化形成致密的SiO2和BN瓷化层,赋予材料突出的耐烧蚀抗冲刷性能,而底层仍然保留着多孔结构使得材料保持较好的隔热性能。

主动热防护技术及自发汗冷却材料的研究进展

热防护技术在航空航天等领域具有重要的应用,其中主动热防护技术通过在基体结构中外加冷却介质起到冷却效果,具有冷却效率高等优点。自发汗冷却技术是一种可实现“智能冷却”的新型主动热防护技术,本文对主动热防护技术及自发汗冷却材料进行简要介绍,对自发汗冷却材料的基体材料和冷却介质进行分类总结,并分析了自发汗冷却材料的发展趋势。

碳化材料的烧蚀性能参数辨识方法

针对碳化材料烧蚀性能参数测量难度大的问题,对基于优化算法的烧蚀性能参数辨识方法进行了研究。根据一维连续模型描述碳化烧蚀材料的内部热响应情况,与公开试验数据进行对比验证,各测量点计算误差均小于15%。采用基函数表征法对材料碳化前后的比热容和导热率进行表征,基函数选取为切比雪夫多项式。根据PICA材料的温度测试试验数据,对材料的热解动力学参数和基函数的待定系数采用遗传算法进行辨识,将辨识得到的材料烧蚀性能参数代入一维连续模型中进行计算,与验证工况下的试验数据进行比对,计算得到的温度曲线平均相对误差小于10%。

热防护材料烧蚀模型的研究进展

对国内外热防护材料烧蚀模型的研究进展进行了综述。首先介绍了非涂层类和涂层类材料的热化学烧蚀模型,然后阐述了发动机内防护材料受颗粒和气流侵蚀的模型,最后讨论了飞行器外防护材料的机械剥蚀模型。分析表明:热化学烧蚀模型主要基于体烧蚀和表面烧蚀守恒方程,但现有表面烧蚀方程中缺乏对气流侵蚀和机械剥蚀的描述,体烧蚀方程中也未能体现炭层的多孔介质特性;颗粒和气流侵蚀模型中,一般将临界孔隙度作为炭层破坏的判据,建立表面剪切应力和孔隙率的经验关系式;机械剥蚀模型中,普遍将现象与侵蚀机制结合,未考虑材料内部性能演变和破坏机制。未来有必要重视飞行器外防护涂层材料的研究,建立更为精准的气流侵蚀、力学剥蚀模型,并与热化学烧蚀模型耦合。

调温服装研究进展与发展趋势的可视化分析

为探析调温服装领域的研究现状和发展趋势,本文基于文献计量法与文献综述法,以中国知网CNKI数据库和Web of Science核心合集数据库中相关文献为数据来源,通过VOSviewer和CiteSpace两款可视化软件,对调温服装研究的年发文量、发文作者、发文机构、发文国家(地区)、关键词共现和聚类、关键词时间线等信息,进行科学知识图谱分析与描述性统计分析,以多维角度探索调温服装的研究热点与前沿。研究结果表明:2000年至今,国内外调温服装研究多应用于消防救援、医用防护、煤矿与隧道施工等处于极端工作环境的行业领域,且更加侧重于从人体生理反应数据对调温服装的性能进行优化,从服装逐步聚焦到着装者自身;调温方式、调温服装的性能评价、调温服装与人体生理指标的相互作用则是当前调温服装领域的研究热点;未来发展应以提升对轻量化、高效能的外源设备和新型调温材料的研发,建立健全相关的行业标准与生产技术规范,开展多维度的性能评价体系,立足于数智协同、研发多功能集成化的智能调温服装为主要方向。

相变储热太阳能上升气流塔:清洁能源层级利用的新路径

太阳能上升气流塔热发电技术是一项新兴的太阳能热利用技术。本文以干旱半干旱地区草场保护为导向,太阳能上升气流塔装置中进行牧草或其他农作物种植,为养殖用草提供来源以及经济效益,并且在内部集成相变材料储热,调控棚内作物适宜生长温度。结果表明:在经过相同时长的加热及冷却后,相变蓄热层最终的中间层平均温度比铝制蓄热层高1.09%,证明了潜热释放对棚内温度调控的有效性,并且建造太阳能上升气流塔种植系统的成本相对于其他大棚降温设备更低廉,能够在环境友好的前提下牧草种植和太阳能热发电并线运行,实现能源的层级利用。

基于气凝胶体系防隔热一体化材料的研究进展

为了推进新型热导率低、轻质高强防隔热一体化材料的开发,综述了3种常见的氧化物气凝胶隔热材料的耐高温性能及其研究进展,包括SiO2气凝胶、Al2O3气凝胶和ZrO2气凝胶等。同时,针对无机氧化物气凝胶材料力学性能较差的问题,介绍了缝合结构气凝胶隔热材料的研究进展。指出:通过引入增强相纤维材料制备的气凝胶复合材料兼具隔热性能与力学性能,在厚度方向引入缝合线可以在结构上改善材料的力学性能,提高材料的整体性。认为:要进一步提高气凝胶的耐高温上限,优化气凝胶材料与其他材料结合的工艺,并缩短制备周期,降低制备成本。