Hao Pei, Spronk Siebe W F, Sevenois Ruben D B, Van Paepegem Wim, Gilabert Francisco A
Department of Materials, Textiles and Chemical Engineering (MaTCh), Mechanics of Materials and Structures (MMS), Tech Lane Ghent Science Park-Campus A, Ghent University (UGent), Technologiepark-Zwijnaarde 46, Zwijnaarde, 9052 Ghent, Belgium.
SIM Program M3, Technologiepark Zwijnaarde 48, Zwijnaarde, 9052 Ghent, Belgium.
Polymers (Basel). 2023 Mar 2;15(5):1262. doi: 10.3390/polym15051262.
The nonlinear behaviour of fibre-reinforced polymer composites (FRPC) in transverse loading is mainly induced by the constituent polymer matrix. The thermoset and thermoplastic matrices are typically rate- and temperature-dependent, complicating the dynamic material characterization process. Under dynamic compression, the microstructure of the FRPC develops local strains and local strain rates whose values can be much higher than those applied at macroscopic level. The correlation between the local (microscopic) values and the measurable (macroscopic) ones still present challenges when applying the strain rate in the range 10-3-103 s-1. This paper presents an in-house uniaxial compression test setup to provide robust stress-strain measurements applying strain rates up to 100 s-1. A semi-crystalline thermoplastic polyetheretherketone (PEEK) and a toughened thermoset epoxy PR520 are assessed and characterized. The thermomechanical response of the polymers is further modelled using an advanced glassy polymer model, naturally capturing the isothermal to adiabatic transition. A micromechanical model of a unidirectional composite undergoing dynamic compression is developed by using both validated polymers as matrices reinforced by carbon fibres (CF) using Representative Volume Element (RVE) models. These RVEs are used to analyse the correlation between the micro- and macroscopic thermomechanical response of the CF/PR520 and CF/PEEK systems investigated at intermediate to high strain rates. Both systems experience an excessive strain localization with local plastic strain about 19% when a macroscopic strain of 3.5% is applied. The comparison of using a thermoplastic and a thermoset as a matrix in composites is discussed with regard to the rate-dependence, the interface debonding and the self-heating effect.
纤维增强聚合物复合材料（FRPC）在横向载荷下的非线性行为主要由构成聚合物基体引起。热固性和热塑性基体通常与速率和温度相关，这使得动态材料表征过程变得复杂。在动态压缩下，FRPC的微观结构会产生局部应变和局部应变率，其值可能远高于宏观层面施加的值。当应变速率在10⁻³ - 10³ s⁻¹范围内时，局部（微观）值与可测量的（宏观）值之间的相关性仍然存在挑战。本文介绍了一种内部单轴压缩试验装置，以提供高达100 s⁻¹应变速率下可靠的应力 - 应变测量。对一种半结晶热塑性聚醚醚酮（PEEK）和一种增韧热固性环氧树脂PR520进行了评估和表征。使用先进的玻璃态聚合物模型进一步模拟了聚合物的热机械响应，自然地捕捉了等温到绝热的转变。通过使用经过验证的聚合物作为基体，采用代表性体积单元（RVE）模型，开发了单向复合材料在动态压缩下的细观力学模型，这些基体由碳纤维（CF）增强。这些RVE用于分析在中高应变速率下研究的CF/PR520和CF/PEEK系统的微观和宏观热机械响应之间的相关性。当施加3.5%的宏观应变时，两个系统都经历了过度的应变局部化，局部塑性应变约为19%。讨论了在复合材料中使用热塑性和热固性材料作为基体在速率依赖性、界面脱粘和自热效应方面的比较。
