## 1 Introduction  
Fiber reinforced composites (FRC) are widely applied in many engineering applications, such as aerospace, wind power and energy, due to their excellent mechanical properties in recent decades [1; 2; 3]. In particular, the laminated composites are more commonly used in aerospace. However, the traditional laminated composites have the disadvantages of relatively low fracture toughness in plane and delamination through thickness. In the recent decade, three-dimensional (3D) textile composites, e.g., weaving, knitting and braiding, have received extensive attention thanks to their excellent anti-delamination characteristics. Specifically, the 3D braided composites were generally recognized as the most promising textile composites, due to their excellent anti-delamination properties [4; 5; 6]. Composite structure in aircraft applications may be subjected to a large number of dynamic loads, e.g., bird strike, blade out and unexpected fragment impact [7; 8]. Therefore, it is necessary and meaningful to understand their dynamic mechanical properties at high strain rates, to guide the design of composite structure that will be used under dynamic loadings in engineering applications. Many efforts have been committed on the dynamic mechanical behavior of the 3D textile composites in recent years. [PERSON] and [PERSON] [9] conducted the ballistic perforation tests of the 3D four-step braided Twaron/epoxy composites, and adopted a \"Fiber inclination model\" to decompose 3D braided composites to geometrical modeling in FEM, proving that the analysis scheme in microstructurescan work. [PERSON] et al. [PERSON] et al. (2010); [PERSON] et al. (2012); [PERSON] et al. (2012) studied in-plane, out-plane compressive and uniaxial tensile mechanical behavior of the 3D four-step braided composites through a series of experiments at different strain rates and discussed its failure modes. The results revealed that the 3D braided composite is sensitive to strain rate and the higher strain rate, the higher failure stress and compressive stiffness. [PERSON] et al. [PERSON] et al. (2013) presented dynamic indentation and small caliber ballistic impact tests for the 3D glass fiber composites; they concluded that the delamination damage at high strain rates was still a dominant failure mode in the 3D woven composites. [PERSON] et al. [PERSON] et al. (2014) reported the compressive mechanical performance and damage mode at quasi-static and high strain rates, based on a meso-structure model of the 3D four-step braided composites; the results proved the validity of meso-structure FEM model. Recently, [PERSON] (2015) experimentally studied dynamic compressive response of the 3D four-step braided composites in three directions (longitudinal, transverse and thickness, respectively), and the experiments of dynamic compressive tests revealed that with increasing the strain rate of composites, the compressive stiffness and failure stress both increased. Most research on the above papers was focused on investigating the mechanical properties on compressive behavior in room temperature, not considering the impact of environment. However, composites structure, usually subject to long-term hygothermal exposures during their service life, such as the aero-engine fan blade with carbon fiber reinforced polymer material, operating in the temperature and humidity environment, is continuously exposed to a hygrothermal environment. Epoxy in composites, as a typical thermoset resin, will absorb the moisture, inducing swelling and plasticization [PERSON] et al. (2014); [PERSON] et al. (2015); [PERSON] et al. (2015). Composites' mechanical advantages such as stiffness and strength will significantly be affected because of hygrothermal aging [PERSON] et al. (2015); [PERSON] et al. (2015); [PERSON] et al. (2015); [PERSON] et al. (2015).