scholarly journals Dynamic damage in carbon-fibre composites

Author(s):  
N. K. Bourne ◽  
S. Parry ◽  
D. Townsend ◽  
P. J. Withers ◽  
C. Soutis ◽  
...  

The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

2020 ◽  
Vol 55 (33) ◽  
pp. 15741-15768 ◽  
Author(s):  
Haibao Liu ◽  
Jun Liu ◽  
Yuzhe Ding ◽  
Jie Zheng ◽  
Xiangshao Kong ◽  
...  

Abstract The present paper describes the results from experimental and theoretical modelling studies on the behaviour of continuous carbon fibre/polymer matrix composites subjected to a relatively low-velocity or high-velocity impact, using a rigid, metallic impactor. Drop-weight and gas-gun tests are employed to conduct the low-velocity and high-velocity impact experiments, respectively. The carbon fibre composites are based upon a thermoplastic poly(ether–ether ketone) matrix (termed CF/PEEK) or a thermoset toughened epoxy matrix (termed CF/Epoxy), which has the same fibre architecture of a cross-ply [03/903]2s lay-up. The studies clearly reveal that the CF/PEEK composites exhibit the better impact performance. Also, at the same impact energy of 10.5 ± 0.3 J, the relatively high-velocity test at 54.4 ± 1.0 m s−1 leads to more damage in both types of composite than observed from the low-velocity test where the impactor struck the composites at 2.56 m s−1. The computationally efficient, two-dimensional, elastic, finite element model that has been developed is generally successful in capturing the essential details of the impact test and the impact damage in the composites, and has been used to predict the loading response of the composites under impact loading.


2021 ◽  
Vol 28 (1) ◽  
pp. 579-591
Author(s):  
Aparna Sridhar ◽  
Ramesh Babu Adusumalli ◽  
Purnima Doddipatla ◽  
Karthik Chethan Venkateshan

Abstract The aim of the study is to develop and investigate the suitability of thermoplastic composites for underwater applications. PA6/PP/PP-g-MA (70 wt%/30 wt%/3 phr) blend is used as a novel matrix to synthesize UDCF composites with balanced strength and toughness even in humid conditions. This novel matrix has around 60% lower water absorption capacity compared to PA6. Short carbon fibres (SCF) and unidirectional carbon fibre fabric (UDCF with 12K rovings) are used as reinforcements. X-ray CT data of injection-molded SCF composites revealed good wetting. However, in the case of compression-molded UDCF composites, a few unwetted zones were found. Comparing dry and wet samples, wet-matrix, wet-SCF composite and wet-UDCF composites had 40, 15, and 25% reduction in their tensile strengths, respectively. However, the impact strength of wet-matrix and wet-UDCF composites increased by 67 and 61%, respectively. Hence, SCF composites having a wet tensile strength of 46 MPa can be used in preparing underwater components due to the low number of interfacial voids. UDCF composites having more interfacial voids are recommended for humid conditions wherein the wet impact strength (11.4 J) and wet tensile strength (266 MPa) are the main criteria.


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