Off-Axis Tension Behaviour of Unidirectional PEEK/AS4 Thermoplastic Composites

Ma, Yifan; Li, Yazhi; Liu, Lu

doi:10.3390/app13063476

Cited by 4 publications

(3 citation statements)

References 29 publications

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“…Nevertheless, the overall findings remain consistent. The strain field is observed to be non-uniform, as demonstrated in studies such as [26,27,33], which were dedicated to CFRP composite. During testing of the G/V, the occurrence of cracks, damage, and delamination becomes clearly visible on DIC maps.…”

Section: Discussion Of the Resultsmentioning

confidence: 86%

“…In [27], a novel oblique end tab was designed to mitigate stress concentration and in-plane bending moments resulting from off-axis tension loading. Finite element analysis and experiments were conducted on polyetheretherketone (PEEK)/AS4 unidirectional thermoplastic composites (CFRTP) to assess the effectiveness of the proposed testing method.…”

Section: Introductionmentioning

confidence: 99%

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Digital Image Correlation Analysis of Strain Fields in Fibre-Reinforced Polymer–Matrix Composite under ±45° Off-Axis Tensile Testing

Bogusz

2023

Polymers

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This study presents an experimental investigation of an in-plane shear of a glass lamina composite using a ±45° off-axis tension test. Typically, the shear stress curve, shear modulus, and in-plane shear strength for composite lamina-type materials are identified. Previous research indicated that a loading rate affects the strength of this composite. This study extends the existing literature by utilising a non-contact optical digital image correlation (DIC) method to measure strain distribution during the test. Two cross-head displacement rates were examined. The obtained strain maps reveal an uneven distribution resembling fabric texture. As the deformation progresses, the differences in the strain pattern increase. Subsequently, a quantitative analysis of the differences between regions with extreme (minimum and maximum) strain values and regions with average values was conducted. Based on these measurements, shear stress–strain curves, indicating variations in their courses, were constructed. These differences may reach several percent and may influence the analysis of numerical simulations. The DIC results were validated using strain gauge measurements, a commonly utilised method in this test. It was demonstrated that the location of the strain gauge installation impacts the results. During the tests, the occurrence of multiple microcracks in the resin was observed, which can contribute to the nonlinearity observed in the shear stress–shear strain curve.

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Section: Discussion Of the Resultsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Digital Image Correlation Analysis of Strain Fields in Fibre-Reinforced Polymer–Matrix Composite under ±45° Off-Axis Tensile Testing

Bogusz

2023

Polymers

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“…They used a one-parameter plasticity model combined with nonlinear elasticity to characterize the nonlinear mechanical properties of unidirectional composites. Ma et al [16] examined the off-axis behavior of PEEK/AS4 unidirectional thermoplastic composites, identifying a linear-elastic relationship during the initial stage and non-linear behavior during the strain-hardening phase.…”

Section: Introductionmentioning

confidence: 99%

Damage assessment through cyclic load-unload tensile tests for ply-level hybrid carbon fiber composites

Casapu,

Fuiorea,

Arrigoni

2024

Express Polym. Lett.

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Composite materials are of increasing interest in aircraft and spacecraft structures, and carbon fiber reinforced polymers (CFRP) have emerged as materials meeting quality standards for structural applications in the aircraft industry. Despite their high mechanical properties, CFRPs are associated with high production costs. Building on recent research by the authors, this paper investigates the use of ply-level hybridization to reduce manufacturing costs while maintaining the mechanical performance of the manufactured material. Focusing on the causes of nonlinear response under off-axis tensile loading, the paper involves cyclic load-unload (LU) tensile tests conducted at off-axis angles of 15°, 30°, and 45° to predict mechanical characteristics and damage evolution. Residual strains are directly extracted from load-unload stress-strain responses. Three distinct methods for estimating cycle modulus are employed and compared for damage variable formulation. The research findings reveal dependencies of both the damage variable and residual strains on the off-axis angle. Furthermore, the method used to assess the modulus during cycling loading significantly influences the damage variable estimation. Encouragingly, the hybrid laminates exhibit reduced internal damage and matrix plasticity compared to reference counterparts, indicating a positive effect on the mechanical performances of hybridized CFRPs in addition to the cost reduction.

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On the experimental determination and prediction of damage evolution in composites via cyclic testing

Souza,

Farahani,

Guedes

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part L:

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This study introduces a novel approach to obtaining and predicting damage evolution laws using quasi-static cyclic testing within the framework of continuum damage mechanics. To achieve this, a comprehensive set of characterization and parameter identification tests was performed. Carbon-epoxy specimens were manufactured using the filament-winding technique, and these laminates were tested using a universal testing machine. Digital image correlation was employed in all experiments to capture strain fields, and an alternative method utilizing the combined loading compression device is presented to obtain mechanical properties. Once the material was characterized, cyclic tests were conducted, including [Formula: see text], [Formula: see text], and [Formula: see text] tensile tests, and shear v-notch tests. These aim to determine damage evolution laws for both conditions, pure and coupled stress states. From these tests, values for damage onset and threshold were obtained and used to define four new parameters. These parameters permit the estimation of degradation relationships for any arbitrary orientation without requiring additional tests. This approach was tested as the proof-of-concept within the positive range of transverse tension and in-plane shear stress domain. The obtained results are promising, justifying its extension to other failure mechanisms. While acknowledging its limitations, this new approach holds potential for implementation in the analysis of progressive failure in fiber-reinforced composite materials, possibly in conjunction with established failure criteria and computational tools, mainly in the finite element method domain.

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Off-Axis Tension Behaviour of Unidirectional PEEK/AS4 Thermoplastic Composites

Cited by 4 publications

References 29 publications

Digital Image Correlation Analysis of Strain Fields in Fibre-Reinforced Polymer–Matrix Composite under ±45° Off-Axis Tensile Testing

Digital Image Correlation Analysis of Strain Fields in Fibre-Reinforced Polymer–Matrix Composite under ±45° Off-Axis Tensile Testing

Damage assessment through cyclic load-unload tensile tests for ply-level hybrid carbon fiber composites

On the experimental determination and prediction of damage evolution in composites via cyclic testing

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