Control of kink-band formation in mille-feuille–structured Al/Al2Cu eutectic alloys

Abstract Results from an experimental investigation on the mechanical behavior of a unidirectional reinforced polymer composite with 50% volume fraction E-glass/vinylester under uniaxial and proportional multiaxial compression are presented. Specimens are loaded in the fiber direction using a servo-hydraulic material testing system for low strain rates and a Kolsky (split Hopkinson) pressure bar for high strain rates, up to 3000 s−1. The results indicate that the compressive strength of the composite increases with increasing levels of confinement and increasing strain rates. Post-test optical and scanning electron microscopy is used to identify the failure modes. The failure mode that is observed in unconfined specimen is axial splitting followed by fiber kink band formation. At high levels of confinement, the failure mode transitions from axial splitting to kink band formation and fiber failure. Also, a new energy based analytic model for studying axial splitting phenomenon in unidirectional fiber-reinforced composites is presented.

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Simulation on kink-band formation during axial compression of a unidirectional carbon fiber-reinforced plastic constructed by X-ray computed tomography images

Advanced Composite Materials ◽

10.1080/09243046.2018.1555387 ◽

2018 ◽

Vol 28 (4) ◽

pp. 347-363 ◽

Cited By ~ 11

Author(s):

Takuya Takahashi ◽

Masahito Ueda ◽

Keisuke Iizuka ◽

Akinori Yoshimura ◽

Tomohiro Yokozeki

Keyword(s):

Computed Tomography ◽

Carbon Fiber ◽

Kink Band ◽

Carbon Fiber Reinforced Plastic ◽

Band Formation ◽

X Ray ◽

Fiber Reinforced Plastic ◽

Computed Tomography Images ◽

Reinforced Plastic ◽

X Ray Computed

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Fatigue Behaviour of Triaxial Braided Composites under Tension-Tension and Compression-Compression Loading

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.809.23 ◽

2019 ◽

Vol 809 ◽

pp. 23-28

Author(s):

Florian Herrla ◽

Helmut Rapp

Keyword(s):

Cyclic Loading ◽

Kink Band ◽

Fatigue Behaviour ◽

Stiffness Degradation ◽

Braided Composites ◽

Material Degradation ◽

Band Formation ◽

Compression Loading ◽

Tension And Compression ◽

Tension Loading

The fatigue behaviour of [0°/±45°] triaxial braided composites is investigated. Tension-tension and compression-compression loading is chosen to study main damage mechanisms and their effect on the stiffness degradation. In both cyclic loading cases a high stiffness degradation can be observed shortly after the start of cyclic loading. Inter-fibre fractures in the braid yarns with subsequent delaminations are responsible for this behaviour during tension-tension loading. Compression-compression loading leads to kink band formation in the axial yarns favoured by yarn undulations. In consequence of the observed material degradation, S-N curves based on a defined level of stiffness degradation are proposed for fatigue dimensioning instead of load cycles to fracture.

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Investigation of the axial compressive behavior of Kevlar fibers using the dynamic loop test

Textile Research Journal ◽

10.1177/0040517518821898 ◽

2019 ◽

Vol 89 (18) ◽

pp. 3825-3838

Author(s):

Ahmad Abuobaid ◽

Raja Ganesh ◽

John W Gillespie

Keyword(s):

Strain Rate ◽

High Speed ◽

Failure Strain ◽

Kink Band ◽

Test Method ◽

Strain Rates ◽

Compressive Failure ◽

Band Formation ◽

Rate Dependent ◽

Strain And Strain Rate

A dynamic loop test method for measuring strain rate-dependent fiber properties was developed. During dynamic loop testing, the fiber ends are accelerated at constant levels of 20.8, 50 and 343 m/s2. The test method is used to study Kevlar® KM2-600, which fails in axial compression due to kink band formation. The compressive failure strain and strain rate at the onset of kink band formation is calculated from the critical loop diameter ( D C), which is monitored throughout the test using a high-speed camera. The results showed that compressive failure strain increases with strain rates from quasi-static to a maximum strain rate of 116 s−1 by a factor of ∼3. Kink angles (φ) and kink band spacing ( D S) were 60 ° ± 2 ° and 16 ± 3 μm, respectively, over the strain rates tested. Rate-dependent mechanisms of compressive failure by kink band formation were discussed.

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