Stress relaxation behaviour of glass fibre reinforced thermoplastic composites and its application to the design of interrupted in situ tensile tests for investigations by X-ray computed tomography

Maurer, Julia; Jerabek, Michael; Salaberger, Dietmar; Thor, Michael; Kastner, Johann; Major, Zoltán

doi:10.1016/j.polymertesting.2022.107551

Cited by 13 publications

(7 citation statements)

References 24 publications

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“…A notable difference between the S40 and S30 composites is that, unlike the S40‐W composites, S30‐W tends to have a much higher stress relaxation. For 100 phr, the stress relaxation in S40 was very close to that in unfilled S40, whereas in the case of S30, the stress relaxation was significantly higher even at 100 phr of W. To gain a deeper understanding, the relaxation profiles were fitted to the stretched exponential Kohlrausch equation 33,34

\frac{σ_{t}}{σ_{o}} = \frac{σ_{\infty}}{σ_{o}} + (\frac{σ_{1}}{σ_{o}}) \exp (- {((), \frac{t}{τ})}^{β})

…”

Section: Resultsmentioning

confidence: 99%

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Stress relaxation and thermal management in highly filled flexible styrene butadiene styrene copolymer‐tungsten composites for high‐energy radiation attenuation

et al. 2023

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A high loading of high‐density and high‐atomic‐number fillers are necessary to obtain desirable X‐ray attenuation characteristics from radiation shields. However, at high filler loadings, the mechanical and viscoelastic properties of polymers are severely impaired, posing a long‐term threat to the mechanical integrity and radiation protection, and the radiation shield temperature may increase after prolonged exposure to ionizing radiation, accelerating the aging of the polymer matrix. In addition, inadequate thermal conduction can make the user uncomfortable while using radiation shields for personal protection. Unfortunately, little attention has been paid to the viscoelastic, stress relaxation, and thermal conductivity‐related features of these densely loaded systems, despite the significant effect of these parameters on long‐term applications and user compliance. In the present work, two different styrene butadiene styrene (SBS) copolymers were used to develop SBS‐tungsten (W) composites. At 500 phr W loading, significant attenuation of X‐rays was achieved along with good tensile strength and elongation at break. The results indicate that the concentration of styrene in the SBS and W loading substantially affected the attenuation, mechanical and rheological properties, and tensile stress relaxation rates. The thermal conductivity increased by >100%, and after gamma irradiation, faster cooling was observed in the W‐loaded composites beyond 300 phr of W loading. The 40% styrene composite demonstrated superior heat transfer at high W loadings owing to the better dispersion and distribution of the W filler in the SBS matrix. Rheological results showed that SBS‐W composites with 30% styrene had a more pronounced Payne effect than those with 40% styrene. Stress relaxation and morphological analyses also revealed changes in the W dispersion in the SBS matrix depending on the styrene content.

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\frac{σ_{t}}{σ_{o}} = \frac{σ_{\infty}}{σ_{o}} + (\frac{σ_{1}}{σ_{o}}) \exp (- {((), \frac{t}{τ})}^{β})

…”

Section: Resultsmentioning

confidence: 99%

“…For 100 phr, the stress relaxation in S40 was very close to that in unfilled S40, whereas in the case of S30, the stress relaxation was significantly higher even at 100 phr of W. To gain a deeper understanding, the relaxation profiles were fitted to the stretched exponential Kohlrausch equation. 33,34…”

Section: Mechanical Properties and Stress Relaxationsmentioning

confidence: 99%

Stress relaxation and thermal management in highly filled flexible styrene butadiene styrene copolymer‐tungsten composites for high‐energy radiation attenuation

et al. 2023

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“…The initiation and growth of damage violates gray level conservation, thus the analysis of correlation residual fields (for converged displacement fields) reveal discontinuities corresponding to damaged zones [ 4 , 24 , 25 ]. Furthermore, FRPs are likely to undergo stress relaxation during tests [ 26 , 27 ]. As reconstructed volumes may last for up to hours, the specimen should be in a steady state to avoid poor image quality due to motion artifacts.…”

Section: Introductionmentioning

confidence: 99%

Damage Detection in a Polymer Matrix Composite from 4D Displacement Field Measurements

Mandić,

Kosin,

Jailin

et al. 2023

Materials

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Standard Digital Volume Correlation (DVC) approaches enable quantitative analyses of specimen deformation to be performed by measuring displacement fields between discrete states. Such frameworks are thus limited by the number of scans (due to acquisition duration). Considering only one projection per loading step, Projection-based Digital Volume Correlation (P-DVC) allows 4D (i.e., space and time) full-field measurements to be carried out over entire loading histories. The sought displacement field is decomposed over a basis of separated variables, namely, temporal and spatial modes. In the present work, the spatial modes are constructed via scan-wise DVC, and only the temporal amplitudes are sought via P-DVC. The proposed method is applied to a glass fiber mat reinforced polymer specimen containing a machined notch, subjected to in situ cyclic tension and imaged via X-ray Computed Tomography. The P-DVC enhanced DVC method employed herein enables for the quantification of damage growth over the entire loading history up to failure.

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“…In situ X-ray experiments are an excellent method for performing mechanical tests and detecting structural changes in the meantime. Especially for rCF fibres, they can be an important source of information, e.g., on the exact fibre orientation, the crack initiation and propagation, the fibre pull-out and post-failure behaviour [ 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Another advantage is that the 3D CT volume scans can be subsequently integrated as a model into simulation software and can thus be used again as a basis for the design of components [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

First Conclusions on Damage Behaviour of Recycled Carbon Staple Fibre Yarn Using X-ray and Acoustic Emission Techniques

et al. 2023

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This paper presents the first results on the characterisation of the damage behaviour of recycled carbon fibre (rCF) rovings manufactured into unidirectionally (UD) reinforced plates. In the first step, the mechanical properties of several material combinations were determined by mechanical tests (tensile, flexural, compression). This proves the usability of the material for load-bearing structures. For example, a tensile modulus of up to 80 GPa and a tensile strength of 800 MPa were measured. Subsequently, the fracture surface was analysed by scanning electron microscopy (SEM) to characterise the fibre–matrix adhesion and to obtain first indications of possible failure mechanisms. Despite the high mechanical properties, poor fibre–matrix adhesion was found for all matrix systems. In situ X-ray microscopy tests were then performed on smaller specimens under predefined load levels as transverse tensile and bending tests. The results provide further predictions of the failure behaviour and can be compared to the previous test results. The three-dimensional scan reconstruction results were used to visualise the failure behaviour of the staple fibres in order to detect fibre pull-out and fibre or inter-fibre failure and to draw initial conclusions about the damage behaviour in comparison to conventional fibre composites. In particular, a benign failure behaviour in the transverse tensile test was demonstrated with this procedure. In addition, first concepts and tests for the integration of AE analysis into the in situ setup of the X-ray microscope are presented.

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Stress relaxation behaviour of glass fibre reinforced thermoplastic composites and its application to the design of interrupted in situ tensile tests for investigations by X-ray computed tomography

Cited by 13 publications

References 24 publications

Stress relaxation and thermal management in highly filled flexible styrene butadiene styrene copolymer‐tungsten composites for high‐energy radiation attenuation

Stress relaxation and thermal management in highly filled flexible styrene butadiene styrene copolymer‐tungsten composites for high‐energy radiation attenuation

Damage Detection in a Polymer Matrix Composite from 4D Displacement Field Measurements

First Conclusions on Damage Behaviour of Recycled Carbon Staple Fibre Yarn Using X-ray and Acoustic Emission Techniques

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