发展具有优异抗冲击性能的先进材料，并揭示相关的耗能机制，一直是冲击防护领域的研究前沿之一。许多材料在高压和高应变率下表现出卓越的抗冲击和防爆特性，但往往在单次冲击加载后失效并丧失防护性能。因此，发展多次冲击吸能的先进材料具有重要的应用需求。剪切增稠流体（STF）是一种应变率越高粘度越大的非牛顿流体，其通常由微纳米颗粒均匀分散在流体介质中形成。当外部载荷作用在STF上时，其粘度会快速增加并耗散一定的能量；当停止加载后，STF会快速恢复到初始状态，因此具有重复吸能的特性。利用STF的流变特性，将其与多孔结构材料进行复合设计，通过STF与结构在冲击加载过程中的强耦合作用，以增强能量耗散效应，从而进一步提升材料的防护能力。

本文围绕STF及其复合材料的动态力学行为展开了以下几个方面的研究工作：

1．研究了高压、超高应变率下STF的动态力学行为，建立了STF可压缩非线性粘性本构模型。制备了不同质量分数的二氧化硅-聚乙二醇（PEG）的STF，并表征了其流变性能。结果表明，随着STF中二氧化硅纳米颗粒质量分数的增加，粘度快速增加。采用强激光诱导冲击加载试验方法，分析了水、PEG、40%二氧化硅质量分数的STF（40wt.%STF）和68%二氧化硅质量分数的STF（68wt.%STF）在冲击载荷下的力学响应规律。研究发现，STF具有高冲击波衰减能力，高质量分数纳米颗粒的STF具有优异的防护性能。同时，建立了PEG、40wt.%STF和68wt.%STF的一阶和二阶Mie-Grüneisen状态方程。通过冲击波加载铝板-STF-铝板数值模拟，验证了状态方程的正确性。

2．研究了STF填充点阵夹层板（SPLTC-STF）在低速冲击下的动态力学行为。采用STF本构模型描述其剪切稀化、剪切增稠和体积压缩性等力学行为，结合动态压缩试验和流固耦合数值计算获得了本构模型参数。通过数值模拟，获得了SPLTC-STF的动态力学行为及宏观响应特性，在内部STF靠近点阵夹层板周围快速流动的过程中，与芯材产生了较强的相互作用，引起SPLTC变形模式的转变，从而提高了SPLTC-STF的吸能能力。

3．研究了SPLTC-STF在高速冲击下的力学行为。通过建立数值计算模型，分析了不同填充物点阵夹层板在平板撞击后的变形行为、速度衰减和动能衰减规律。结果表明，随着撞击速度的增加，SPLTC-STF的最大速度衰减能力越强。同时，较高粘度的STF能够进一步增强耦合耗能能力，实现更好的防护性能。通过爆炸加载试验和数值模拟，也表明SPLTC-STF具有良好的防爆性能，在爆炸与冲击防护领域中具有重要的应用价值。

4．制备了STF微胶囊-硅橡胶基复合材料（SR-STF），测量了SR-STF复合材料静态和动态力学行为，发现SR-STF复合材料表现出对加载速率的智能适应性，即在低应变速率下，SR-STF复合材料的刚度随着STF微胶囊含量的增加而减小，而在高应变率下，刚度随着STF微胶囊含量的增加而快速增加。基于试验结果，建立了SR-STF复合材料的超弹性本构模型，准确预测了材料的动力学行为。

本文获得了STF在高压高应变率下应力波衰减和能量吸收规律，并建立了STF的可以缩非线性粘性本构方程。揭示了STF填充点阵夹层板在低速和高速冲击下的动态力学行为和能量耦合耗散机制。首次制备了STF微胶囊填充SR复合材料，并得到了SR-STF在不同载荷条件下的力学性能。

Developing advanced materials with excellent impact resistance and revealing the related energy dissipation mechanisms have always been one of the research frontiers in the field of impact protection. Many materials exhibit excellent impact resistance and blast protection capacities under high pressure and high strain rates, however, they often fail and lose their protective performance after experiencing a single impact loading. Therefore, developing advanced materials capable of absorbing energy during multiple impacts has significant application requirements. Shear-thickening fluid (STF) is a type of non-Newtonian fluid whose viscosity increases with the strain rate, usually formed by uniformly dispersing micron or nanosized particles in a fluid medium. When an external load is applied to the STF, its viscosity rapidly increases and dissipates a certain amount of energy; when the load is removed, the STF quickly returns to its initial state, thus exhibiting the ability to repeatedly absorb energy. By utilizing the rheological properties of STFs and combining them with porous structured materials in a composite design, the strong coupling effect between the STF and the structure during impact loading can be used to enhance the energy dissipation effect, thereby further improving the protective capacity of composite material.

In this dissertation, the dynamic mechanical behavior of STF and their composite materials was investigated. The following research aspects were performed:

Firstly, the dynamic mechanical behavior of STFs under high pressure and ultra-high strain rates was studied, and a compressible nonlinear viscoelastic constitutive model of STF was established. The silica nanoparticle-polyethylene glycol (PEG) STF with different mass fractions were fabricated, and their rheological properties were characterized. The results showed that the viscosity increased with increasing mass fraction of silica nanoparticles in the STF. A high-intensity laser-induced shock loading experimental method was employed to analyze the mechanical response of water, PEG, the STF with 40% silica mass fraction (40wt.% STF), and the STF with 68% silica mass fraction (68wt.% STF) under shock loading. It was found that the STF exhibited high shock wave attenuation capability, and STF with high mass fraction nanoparticles has excellent protective properties. At the same time, the first-order and the second-order Mie-Grüneisen equations of state were established for PEG, 40wt.% STF, and 68wt.% STF, which were verified through numerical simulation of shock wave loading on aluminum-STF-aluminum plates.

Secondly, the dynamic behavior of sandwich panels with lattice truss core filled by STF (SPLTC-STF) under low-velocity impacts was investigated. The STF constitutive model was used to describe the mechanical behavior of shear thinning, shear thickening, and volume compressibility. The constitutive model parameters were obtained through dynamic compression experiments and fluid-solid coupling numerical simulations. Through the numerical simulations, the dynamic mechanical behavior and macroscopic response characteristics of SPLTC-STF were obtained. During the rapid flow of the internal STF near the perimeter of the SPLTC, it had a strong interaction with the lattice truss core, causing a transformation in the deformation mode of the SPLTC and enhancing the energy absorption capacity of SPLTC-STF.

Thirdly, the mechanical behavior of SPLTC-STF under high-speed impact was investigated. By establishing the numerical simulation models, the deformation behavior, velocity attenuation, and kinetic energy attenuation of the SPLTC with various fillers were analyzed. The results show that as the impact velocity increases, the maximum velocity attenuation capacity of SPLTC-STF was increased. At the same time, STF with higher viscosity can further enhance the coupled energy dissipation capacity and achieve better protective performance. The dynamic response of SPLTC with various fillers under explosive loading was also investigated through experiments and numerical simulations, demonstrating that the SPLTC-STF has excellent explosion protection performance and is of great application value in the fields of explosion and impact protection.

Finally, the silicone rubber composites with STF microcapsules (SR-STF) were fabricated, and quasi-static and dynamic mechanical behavior of the SR-STF composites were also measured. It was found that the SR-STF composite exhibit intelligent adaptability to loading rates. At low strain rates, the stiffness of SR-STF composite decreases with the increase of STF microcapsule content, while at high strain rates, the stiffness increases rapidly with the increase of STF microcapsule content. Based on experimental results, a hyperelastic constitutive model for SR-STF composite materials was established, accurately predicting the dynamic mechanical behavior of the SR-STF composites.

This dissertation obtained the laws of stress wave attenuation and energy absorption of STF under high pressure and high strain rates, and established a volume compressible non-linear viscous constitutive equation for STF. It revealed the dynamic mechanical behavior and energy coupling dissipation mechanism of SPLTC-STF under low and high velocity impacts. For the first time, SR-STF composite materials were prepared, and the mechanical properties of SR-STF under different load conditions were obtained.