Characterization of unidirectional carbon fiber reinforced polyamide-6 thermoplastic composite under longitudinal compression loading at high strain rate

Abstract

Abstract. In the presented work, an experimental investigation has been performed to characterize the strain rate dependency of unidirectional carbon fiber reinforced polyamide-6 composite for longitudinal compression loading. An end-loaded compression specimen geometry, suitable for contactless optical strain measurement via digital image correlation and dynamic loading in a split-Hopkinson pressure bar, was developed. For the dynamic experiments at a constant strain rate of 100 s −1 a modified version of the Dynamic Compression Fixture, developed by Koerber and Camanho [Koerber and Camanho, Composites Part A, 42, 462-470, 2011] was used. The results were compared with quasi-static test results at a strain rate of 3 · 10 −4 s −1 using the same specimen geometry. It was found that the longitudinal compressive strength increased by 61% compared to the strength value obtained from the quasi-static tests.

High Strain Rate Characterization of Thermoplastic Fiber-Reinforced Composites under Compressive Loading

“…It can be concluded that the material is not strain rate dependent and the measurement of dynamic strain by DIC allows a more accurate comparison with respect to the measurement of the quasi-static strain by the video strain gauge system. PPSCFC mechanical behavior discussed does not coincide with the behavior observed on similar materials (thermoplastic matrixes reinforced with carbon fiber) [11,16,19,23,27,38]. This can be explained by the effect of carbon fiber on the resin (PPS) crystallization reported in open literature, where it has been found that transcrystallinity on the fiber-resin interphase affects the mechanical properties of the composite [32,38,[47][48][49].…”

“…Data acquisition and conditioning system signals were post-processed using an in-house Python program, which computes the stress, strain, and strain rate on the specimen using the classical SHPB analysis based on the one-dimensional wave propagation theory, which implies elastic deformation in the bars during the tests, unidirectional elastic pulses propagate along the bars, uniform deformation process in the specimen, and no dispersion of waves throughout the bars and the specimen [11,24,26,28,29].…”

“…Efforts have been made to determine the relation between fiber-reinforced polymer matrix composite (FRPC) mechanical properties at high strain rates and material configuration (resin and fiber length, concentration and orientation), using different high strain rate test techniques. Different authors have report and analyzed several researches as a state of the art in this topic; however, most of the studies are focused on thermoset composites, especially epoxy and polyester matrices reinforced with glass and carbon fibers [3,5,[7][8][9][10][11][12][13]. The few works found in open literature about thermoplastic composites studied polyamide-reinforced composites (with glass and carbon fiber with different fiber configurations), ethylene-propylene copolymer (EPC) matrix reinforced with discontinuous glass fibers, commingled e-glass/polypropylene woven fabric composite, glass fiber-reinforced polypropylene (PP) and polybutene-1 (PB-1), and AS4 graphite/polyetheretherketone (PEEK) thermoplastic composite [4,11,[14][15][16][17][18][19][20]; however there is a lack of information about PPS matrix composite's behavior.…”

“…Among the several techniques to achieve high strain rates for tests [21], the split-Hopkinson pressure bar testing is often used for composite materials [3,5,10,18,[22][23][24][25][26][27][28][29], where both the specimen stress-time and the specimen strain-time response are calculated from the strain waves measured on the bars. Additionally, high-speed camera technology with high resolution allow to apply optical and contactless strain field measurement techniques such as digital image correlation (DIC), to obtain accurate data reduction possibilities and more information on the distribution of strain over the specimen surface, which will be later employed in the dynamic material characterization [11,26,30,31]. Within this context, the present work uses these techniques to characterize the strain rate effects on the mechanical behavior of PPS matrix carbon fiber-reinforced composite under compressive loadings in both static and dynamic regimes.…”

Strain rate effect on the mechanical behavior of polyamide composites under compression loading

“…A number of studies were performed in recent years on the strain rate effect on the mechanical properties of thermoplastic composites [38][39][40][41][42][43]. Few works [44][45][46] were reported on the dynamic compressive response of polyamide composites. Strain-rate dependency is one of the material behaviors of fiber reinforced composites being focused on because many primary structural applications involve exposure to impact and crash loads.…”