Mechanical Responses of Carbon Fiber Fabric Composites at Various Strain Rates

Abstract

Fiber-reinforced plastic composites are extensively used in structural applications due to their exceptional strength-to-weight ratio, versatility, and adaptability. Among many Fiber-reinforced plastic composites, plain weave textile composites (PWTC) are particularly notable for their balanced mechanical properties under multidirectional loading, which make them ideal for complex structural designs in aerospace, automotive, and other high-performance fields. In aerospace structures, materials are subjected to dynamic loading conditions during events such as impacts or crash landings, requiring an understanding of their mechanical behavior across various strain rates. Similarly, in the automotive industry, crashworthiness and energy absorption are key considerations, highlighting the need to study how PWTC responds under various strain rates. High-performance fields, where reliability and safety under varying loading conditions are critical, also demand a thorough strain rate characterization to optimize material design and structural integrity. Addressing these demands necessitates systematic research into the rate-dependent properties of PWTC across a wide range of strain rates. However, the behavior of PWTC under different strain rates remains inadequately understood. This knowledge gap is primarily attributed to the absence of standardized testing protocols for dynamic conditions and the technical difficulties in performing such tests. These challenges include optimizing specimen geometries and gripping methods to ensure reliable data acquisition without compromising the integrity of the testing apparatus. Addressing these limitations is essential to accurately predict the dynamic performance of PWTC and to develop composite structures that can reliably withstand varying loading conditions. To bridge this critical knowledge gap, this research systematically investigates the rate-dependent mechanical behavior of PWTC across a wide range of strain rates by combining experimental testing with micromechanics-based finite element analysis. The experimental approach begins with tensile and shear tests at low and intermediate strain rates, which provide a foundational understanding of how stiffness, strength, and failure strain evolve with increasing strain rates. These tests also offer comparative insights into the contributions of the epoxy matrix, highlighting its role in the composite’s overall mechanical response. Building upon this foundation, high strain rate testing is conducted using a customized split Hopkinson tension bar setup. This setup addresses specific challenges of dynamic testing, including optimized specimen geometries and advanced gripping techniques, to ensure accurate stress–strain data acquisition. High-speed imaging further captures detailed failure mechanisms and damage progression under extreme loading conditions, extending the understanding gained from lower strain rate tests and providing valuable data for subsequent modeling efforts. The computational aspect of this study focuses on the development of a micromechanics-based finite element analysis to simulate the rate-dependent behavior of PWTC. This model explicitly incorporates the geometric and material properties of carbon fibers and the epoxy matrix. The rate-dependent characteristics of the epoxy are modeled using the modified Johnson-Cook damage model, with parameters calibrated based on the experimental results. This integrated approach allows for an in-depth analysis of the interactions between constituent materials, capturing the mechanisms of plasticity, damage initiation, and failure progression within the composite. The finite element analysis not only serves as a predictive tool for understanding the dynamic response of PWTC but also provides insights into the material and structural factors that influence its performance under varying strain rates. The findings of this research offer significant contributions to the field by addressing longstanding challenges associated with high strain rate testing and enhancing the understanding of the dynamic behavior of PWTC. By providing reliable experimental data and robust predictive models, this study improves the accuracy of design methodologies for composite structures subjected to dynamic loading. The integrated approach adopted in this research establishes a strong foundation for exploring other textile composite architectures and understanding their strain rate-dependent behavior. These advancements pave the way for the development of more resilient and efficient composite materials, ensuring their suitability for a broader range of engineering applications in environments where dynamic loading is critical.