## 1 Introduction
These three dominant failure mechanisms resemble those proposed by the NU-Daniel failure criteria. But the formulation is quite complicated, and there is no description about the dynamic loading effect on the failure criterion they proposed. While numerical models [26] indeed face challenges, such as not fully capturing all manufacturing defects, neglecting environmental conditions, and managing discrepancies in model dimensions, the advantages they offer are undeniable. Particularly, in the realm of probabilistic investigations under combined load cases, the benefits of numerical modeling highlighted earlier prove invaluable. In addition to the criteria derived from analytical considerations, some authors also used experimental testing and numerical modeling to determine failure envelopes. [PERSON] et al. [27] and [PERSON] et al. [28] conducted comprehensive reviews on the failure analysis of composites based on micromechanical modelling under multiaxial loadings of UD fiber-reinforced polymer composites. They provided detailed review of the construction of representative volume elements within the framework of micromechanical modelling, covering the spatial distribution of fibers embedded in a matrix, constitutive models of material constituents, periodic boundary conditions and failure analysis of UD fiber-reinforced polymer composites under various loadings. Nonetheless, the constitutive model of fiber requires advancement from a physics perspective, taking into account the nonlinearity of its behavior as well as the variances in tensile and compressive loadings. Additionally, the researchers did not establish any connections between strain rates and the mechanical properties or behaviors of UD fiber-reinforced polymer composites. It is crucial to note that most of polymer composites exhibit nonlinear behaviors and strain-rate-dependent properties. Most works on strain-rate-dependent properties of composite materials focus on metal alloys or metal composites; nevertheless, very few works have been devoted to investigating the strain-rate-dependent properties of fiber-reinforced polymer composites. Furthermore, in the majority of research papers discussing strain rate, the influence of high-speed impacts or high strain rates on the mechanical behavior of composites is often addressed [29; 30; 31; 32; 33]. However, there is no consolidated methodology in place to standardize this aspect. [PERSON] et al. [34; 35] examined the impact of strain rate on the tensile strength and fracture energy of a variety of fiber-reinforced composites. However, given the limitations inherent to experimental methods and the benefits provided by computational tools, it is more feasible to study these intricate multiphase issues through numerical analysis. In [36], only cases with a low strain rate were considered, and the influence of high strain rates on the mechanical behavior of composites was examined without further investigations. This paper presents a novel method for analyzing the behavior of UD composite materials subjected to compression in the direction transverse to reinforcement and shear within the plane of a UD layer, considering various strain rates including quasi-static, static, and dynamic conditions. The specific focus of the study is on a CFRP AS4/3501-6, chosen as the material of interest to investigate the strength of a UD composite in relation to strain rate. Experimental data, obtained from [7], were digitized and utilized for analysis and validation. The proposed theory offers a foundation for predicting fracture and progressive damage in UD carbon plastics under various loading scenarios. Moreover, this method can be further adapted and extended to explore other aspects of the material's behavior and structural performance, providing valuable insights for design and analysis purposes.