Split Hopkinson pressure bar (SHPB) technique is used to determine the dynamic strength of reactive powder concretes (RPCs) with different steel-fiber contents. Two types of pulse shapers with different thicknesses are considered to reduce the high-frequency-oscillation effect and achieve a nearly constant strain rate over a certain deformation range. It is known that the compressive strength of concrete-like materials is hydrostatic-stress-dependent, and the apparent dynamic strength enhancement comes from both the effects of the hydrostatic stress and strain rate. In order to differentiate them, numerical method is used to calculate the contribution of the hydrostatic stress, and then the genuine strain-rate effect on dynamic compressive strength of RPCs is determined. In addition, the effect of steel-fibers on dynamic strength and failure mode of RPCs is discussed.

借鉴聚合物结晶学相关理论，建立了一个针对该类材料的新的热力学本构关系，通过与已有实验结果相比较，发现理论预测值与实验吻合较好。

Elasticmemorycomposites (EMCs) are receivingmore attention in deployable spacecraft industry because they can realizemuch higher packaging strains without damage and automatically recover to their original shapes when subjected to a specific thermomechanical cycle. Experimental researches have revealed that microbuckling and post-microbuckling responses of compressed fibers in the soft matrix are the primary deformationmechanism ofEMCsto realize higher packaging strains than traditionalcomposites.However, a thorough understanding about the deformation mechanism of EMCs has not yet been achieved. This paper presents a new shear/tension microbuckling solution to study the deformation and failure process of EMC laminates under bending. The microbucklingwavelength, critical compressive stress and strain for carbon-fiber/resin EMC laminates are calculated, and different theoretical solutions are compared with the experimental observation. Moreover, the possible failure modes of this type of materials arediscussed as well.

通过对活性粉末混凝土材料进行Hopkinson压杆冲击压缩实验，得到不同钢纤维含量的活性粉末混凝土在不同应变率下的应力-应变全曲线，并给出了不同应变率下材料的动态压缩强度和动态增长因子，实验结果表明，活性粉末混凝土具有应变率敏感性，钢纤维的掺入部分提高了材料的冲击压缩性能。

In this paper, the viscoelastic behavior of PI/SiO2 nanocomposite thin films under constant and fatigue tensile loading was studied. The cyclic hardening and viscous dissipation of PI/SiO2 nanocomposite thin films during the fatigue process were experimentally investigated and analyzed by storage modulus, loss modulus and phase lag. The time-dependent deformation under constant and fatigue loading was simulated based on two viscoelastic models known as Burger model and Findley power law. Standard parameter analysis methodology was employed to interpret the structure–property relationship and deformation mechanisms of this kind of nanocomposites. In addition, the effects of nano-silica content, stress level and loading pattern (constant or fatigue loading) on the creep resistance of materials were discussed as well.