Xiao Xinke, Wang Penglei, Guo Anxiao, Han Linzhuang, Yang Yunhao, He Yalin, Cai Xuanming
Henan International Joint Laboratory of Dynamics of Impact and Disaster of Engineering Structures, Nanyang Institute of Technology, Nanyang 473004, China.
School of Aerospace Engineering, North University of China, Taiyuan 030051, China.
Materials (Basel). 2025 Aug 6;18(15):3686. doi: 10.3390/ma18153686.
Short fiber-reinforced polymer (SFRP) has been extensively applied in structural engineering due to its exceptional specific strength and superior mechanical properties. Its mechanical behavior under medium strain rate conditions has become a key focus of ongoing research. A comprehensive understanding of the response characteristics and underlying mechanisms under such conditions is of critical importance for both theoretical development and practical engineering applications. This study proposes an innovative three-dimensional (3D) multiscale constitutive model that comprehensively integrates mesoscopic fiber-matrix interface effects and pore characteristics. To systematically investigate the dynamic response and damage evolution of SFRP under medium strain rate conditions, 3D-printed SFRP porous structures with volume fractions of 25%, 35%, and 45% are designed and subjected to drop hammer impact experiments combined with multiscale numerical simulations. The experimental and simulation results demonstrate that, for specimens with a 25% volume fraction, the strain rate strengthening effect is the primary contributor to the increase in peak stress. In contrast, for specimens with a 45% volume fraction, the interaction between damage evolution and strain rate strengthening leads to a more complex stress-strain response. The specific energy absorption (SEA) of 25% volume fraction specimens increases markedly with increasing strain rate. However, for specimens with 35% and 45% volume fractions, the competition between these two mechanisms results in non-monotonic variations in energy absorption efficiency (EAE). The dominant failure mode under impact loading is shear-dominated compression, with damage evolution becoming increasingly complex as the fiber volume fraction increases. Furthermore, the damage characteristics transition from fiber pullout and matrix folding at lower volume fractions to the coexistence of brittle and ductile behaviors at higher volume fractions. The numerical simulations exhibit strong agreement with the experimental data. Multi-directional cross-sectional analysis further indicates that the initiation and propagation of shear bands are the principal drivers of structural instability. This study offers a robust theoretical foundation for the impact-resistant design and dynamic performance optimization of 3D-printed short fiber-reinforced polymer (SFRP) porous structures.
短纤维增强聚合物（SFRP）因其出色的比强度和优异的力学性能而在结构工程中得到广泛应用。其在中等应变率条件下的力学行为已成为当前研究的关键焦点。全面了解此类条件下的响应特性和潜在机制对于理论发展和实际工程应用都至关重要。本研究提出了一种创新的三维（3D）多尺度本构模型，该模型全面整合了细观纤维 - 基体界面效应和孔隙特征。为了系统研究SFRP在中等应变率条件下的动态响应和损伤演化，设计了体积分数分别为25%、35%和45%的3D打印SFRP多孔结构，并结合多尺度数值模拟进行落锤冲击试验。实验和模拟结果表明，对于体积分数为25%的试样，应变率强化效应是峰值应力增加的主要贡献因素。相比之下，对于体积分数为45%的试样，损伤演化与应变率强化之间的相互作用导致应力 - 应变响应更为复杂。25%体积分数试样的比能量吸收（SEA）随应变率增加而显著增加。然而，对于体积分数为35%和45%的试样，这两种机制之间的竞争导致能量吸收效率（EAE）出现非单调变化。冲击载荷下的主要失效模式是以剪切为主的压缩，随着纤维体积分数的增加，损伤演化变得越来越复杂。此外，损伤特征从较低体积分数下的纤维拔出和基体折叠转变为较高体积分数下脆性和延性行为的共存。数值模拟与实验数据表现出高度一致性。多方向横截面分析进一步表明，剪切带的萌生和扩展是结构失稳的主要驱动因素。本研究为3D打印短纤维增强聚合物（SFRP）多孔结构的抗冲击设计和动态性能优化提供了坚实的理论基础。
