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Krzak, A., Al-Maqdasi, Z., Nowak, A. J. & Joffe, R. (2024). Effect of Thermomechanical Loading at Low Temperatures on Damage Development in Glass Fiber Epoxy Laminates. Materials, 17(1), Article ID 16.
Open this publication in new window or tab >>Effect of Thermomechanical Loading at Low Temperatures on Damage Development in Glass Fiber Epoxy Laminates
2024 (English)In: Materials, E-ISSN 1996-1944, Vol. 17, no 1, article id 16Article in journal (Refereed) Published
Abstract [en]

Due to the high interest in the use of glass/epoxy laminates in aerospace applications, aviation, and as cryogenic tanks, it is crucial to understand the behavior of composites under challenging environmental conditions. Polymer composites are exposed to low temperatures, including cryogenic temperatures, which can lead to the initiation of microdamage. This paper investigates damage initiation/accumulation and its influence on the properties of cross-ply woven glass fiber epoxy composites at low temperatures compared to room temperature conditions. To evaluate the influence of a low-temperature environment on the mechanical performance of glass fiber reinforced epoxy composite (GFRP) laminates, three types of test campaigns were carried out: quasi-static tensile tests and stepwise increasing loading/unloading cyclic tensile tests at room temperature and in a low-temperature environment (−50 °C). We demonstrated that the initial stiffness of the laminates increased at low temperatures. On the other hand, there were no observed changes in the type or mechanism of developed damage in the two test conditions. However, the reduction in stiffness due to the accumulated damage was more significant for the laminates tested at low temperatures (~17% vs. ~11%). Exceptions were noted in a few formulations where the extent of damage at low temperatures was insignificant (<1%) compared to that at room temperature. Since some of the studied laminates exhibited a relatively minor decrease in stiffness (~2–3%), we can also conclude that the formulation of matrix material plays an important role in delaying the initiation and formation of damage.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2024
Keywords
epoxy/glass, laminates, low temperature, mechanical test, stiffness degradation
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-103859 (URN)10.3390/ma17010016 (DOI)2-s2.0-85181973967 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-01-22 (joosat);

Funder: Polish Ministry of Education and Science (DWD/5/0435/2021);

Full text license: CC BY

Available from: 2024-01-22 Created: 2024-01-22 Last updated: 2024-01-22Bibliographically approved
Kneissl, L. M., Gonçalves, G., Joffe, R., Kalin, M. & Emami, N. (2023). Mechanical properties and tribological performance of polyoxymethylene/short cellulose fiber composites. Polymer testing, 128, Article ID 108234.
Open this publication in new window or tab >>Mechanical properties and tribological performance of polyoxymethylene/short cellulose fiber composites
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2023 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 128, article id 108234Article in journal (Refereed) Published
Abstract [en]

Natural fibers are promising bio-based materials to use as reinforcements in polymer composites as often more affordable and accessible alternatives to fossil-based fibers, especially because of their superior sustainability. Polyoxymethylene (POM) is a widely used engineering thermoplastic, which has a melting temperature suitable for processing with natural fibers. In this study, such composites consisting of POM and regenerated cellulose fibers have been developed and studied in terms of their mechanical, thermal, tribological and structural properties. Tensile and flexural moduli increased with incorporation of 30 wt% fibers up to 89% and 79% respectively, crystallinity increased as well by a maximum of approx. 11% at 30% fiber content. Furthermore, the specific wear rate was improved for the composite with 10 wt% fibers, showing a decrease of roughly 80%. This study investigates the processing parameters and tribo-mechanical performance of POM-based natural fiber composites as an important route towards future sustainable polymer composites in load bearing applications.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Cellulose fibers, Characterization, Polyoxymethylene, Processing, Tribology
National Category
Composite Science and Engineering
Research subject
Machine Elements; Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-101977 (URN)10.1016/j.polymertesting.2023.108234 (DOI)2-s2.0-85174143660 (Scopus ID)
Funder
EU, Horizon 2020, 860246
Note

Validerad;2023;Nivå 2;2023-11-08 (marisr);

License fulltext: CC BY-NC-ND

Available from: 2023-10-31 Created: 2023-10-31 Last updated: 2023-11-08Bibliographically approved
Freire, R. T. .., Nunes, S. G., Amico, S. C., Al-Ramahi, N. J., Joffe, R. & Varna, J. (2023). On Determination of the Linear Viscoelastic Compliance and Relaxation Functions for Polymers in One Tensile Test: [Об определении функций линейной вязкоупругой податливости и релаксации полимеров в одном испытании на растяжение]. Mechanics of composite materials, 58(6), 765-786
Open this publication in new window or tab >>On Determination of the Linear Viscoelastic Compliance and Relaxation Functions for Polymers in One Tensile Test: [Об определении функций линейной вязкоупругой податливости и релаксации полимеров в одном испытании на растяжение]
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2023 (English)In: Mechanics of composite materials, ISSN 0191-5665, E-ISSN 1573-8922, Vol. 58, no 6, p. 765-786Article in journal (Refereed) Published
Abstract [en]

Usually, the viscoelastic (VE) response of polymers for applications in composites is obtained in uniaxial strainor stress-controlled tests. However, analyzing multimaterial structures by the Finite Element Method (FEM) or by other numerical or analytical tools, a material model in terms of a complete set of compliance functions and/or relaxation functions is required. In this paper, a methodology and exact analytical expressions for calculating the whole set of VE functions is presented based on the relaxation modulus E(t)and Poisson’s ratio v (t) determined in strain-controlled tests. The method is based on Laplace transforms, where an exact inversion is possible if a linear VE model with functions in Prony series is used. Results of the analytical model are compared with the FEM simulation, where specific boundary conditions to determine each particular VE function are used. Finally, the applicability of the so-called quasi-elastic method is investigated, where the expressions of elasticity theory are used to calculate a given viscoelastic function at an instant of time tk using the instant values of E(tk) and v(tk). For isotropic materials, the three approaches render almost coinciding results.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
FEM, Laplace transforms, linear viscoelasticity, quasi-elastic method, relaxation
National Category
Applied Mechanics
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-95466 (URN)10.1007/s11029-023-10067-0 (DOI)000916623000002 ()2-s2.0-85146393623 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-02-09 (hanlid);

Funder: Higher Education Improvement Coordination (CAPES/Brazil); ERDF (1.1.1.2/VIAA/4/20/641); Swedish Foundation for International Cooperation in Research and Higher Education (STINT);

Reference to this article in Russian:  Фрейре, Р.Т.С., Нуньес С.Г., Амико, С.К. et al. Об определении функций линейной вязкоупругой податливости и релаксации полимеров в одном испытании на растяжение. Механика композитных материалов 58 (6), 1095-1124 (2022). https://doi.org/10.22364/mkm.58.6.01

Available from: 2023-02-09 Created: 2023-02-09 Last updated: 2023-02-14Bibliographically approved
Bianchi, O., Cruz, J. A., Paim, L., Lavoratti, A., Al-Maqdasi, Z., Amico, S. C., . . . Joffe, R. (2023). Rheology, curing and time-dependent behavior of epoxy/carbon nanoparticles systems. Journal of Applied Polymer Science, Article ID e54821.
Open this publication in new window or tab >>Rheology, curing and time-dependent behavior of epoxy/carbon nanoparticles systems
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2023 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, article id e54821Article in journal (Refereed) Epub ahead of print
Place, publisher, year, edition, pages
John Wiley and Sons Inc, 2023
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-101958 (URN)10.1002/app.54821 (DOI)2-s2.0-85174582769 (Scopus ID)
Note

Funder: Conselho Nacional de Desenvolvimento Científico e Tecnológico (305814/2021-4); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (FinanceCode 001); STINT/CAPES (88881.304743/2018-01)

Available from: 2023-10-31 Created: 2023-10-31 Last updated: 2023-11-30
Al-Maqdasi, Z., Pupure, L., Emami, N. & Joffe, R. (2023). Time-dependent properties of high-density polyethylene with wood/graphene nanoplatelets reinforcement. Polymer Composites, 44(1), 465-479
Open this publication in new window or tab >>Time-dependent properties of high-density polyethylene with wood/graphene nanoplatelets reinforcement
2023 (English)In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 44, no 1, p. 465-479Article in journal (Refereed) Published
Abstract [en]

The effect of graphene nanoplatelets (GNPs) on the long-term performance of wood fiber/high-density polyethylene (HDPE) composite is investigated by using short-term creep tests with an efficient, faster data analysis approach. Previously, it was shown that the addition of GNPs at 15 wt% into HDPE reduces the viscoplastic (VP) strain developed during 2 h creep by ~50%. The current study shows that 25 and 40 wt% wood content in HDPE reduce the VP strains developed during 2 h creep time by >75% with no noticeable effect of the increased wood content. However, further addition of GNPs results in more than 90% total reduction in the VP strains. The current study shows that the development of the VP strains in the hybrid composites follows Zapas model. Viscoelastic (VE) response of these composites is nonlinear and thus is described by Schapery's model. Parameters for VP and VE models are obtained from the creep experiments and were validated in a separate loading-unloading test sequence. Results show a very good agreement between experiments and predictions for the studied materials as long as the micro-damage is not present.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
creep, graphene nanoplatelets, multiscale composites, time-dependent properties, viscoelasticity, viscoplasticity, wood fibers
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-90137 (URN)10.1002/pc.27110 (DOI)000877029700001 ()2-s2.0-85141407844 (Scopus ID)
Funder
European Regional Development Fund (ERDF), 1.1.1.2/VIAA/4/20/646EU, Horizon 2020, 777810 Nano2Day
Note

Validerad;2023;Nivå 2;2023-04-19 (hanlid);

Available from: 2022-04-08 Created: 2022-04-08 Last updated: 2023-04-19Bibliographically approved
Al-Maqdasi, Z., Pupure, L., Emami, N. & Joffe, R. (2022). Analysis of long-term performance of wood polymer composites with added multifunctionality. In: 80th International Scientific Conference of the University of Latvia - Advanced Composites and Applications: Book of Abstracts. Paper presented at 80th International Scientific Conference of the University of Latvia, February 15, 2022, Riga, Latvia (pp. 9). Riga: University of Latvia
Open this publication in new window or tab >>Analysis of long-term performance of wood polymer composites with added multifunctionality
2022 (English)In: 80th International Scientific Conference of the University of Latvia - Advanced Composites and Applications: Book of Abstracts, Riga: University of Latvia , 2022, p. 9-Conference paper, Oral presentation with published abstract (Other academic)
Place, publisher, year, edition, pages
Riga: University of Latvia, 2022
National Category
Composite Science and Engineering Polymer Technologies
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-96169 (URN)
Conference
80th International Scientific Conference of the University of Latvia, February 15, 2022, Riga, Latvia
Note

Funder: NANO2Day (777810)

Available from: 2023-03-16 Created: 2023-03-16 Last updated: 2024-01-08Bibliographically approved
Varna, J., Loukil, M. S., Pupurs, A. & Joffe, R. (2022). Damage and Failure Analysis for Composites. In: Reference Module in Materials Science and Materials Engineering: . Elsevier
Open this publication in new window or tab >>Damage and Failure Analysis for Composites
2022 (English)In: Reference Module in Materials Science and Materials Engineering, Elsevier, 2022Chapter in book (Refereed)
Abstract [en]

Intralaminar cracking in plies of composite laminates is the first microdamage mode that affects thermo-elastic properties and may trigger local delaminations and final failure of the composite. Intralaminar cracks are like tunnels running along the fiber direction in the ply. The number of cracks increases with the increase of the applied load or with the number of cycles in fatigue loading. In this article, the cracking evolution is analyzed distinguishing two phases in development: initiation and propagation. For laminates with thick plies, the initiation ends with triggering sudden propagation and, therefore, concept of statistical initiation stress distribution in the ply together with Monte Carlo method is used for analysis. For thin-ply laminates, crack initiation does not lead to immediate propagation and the energy release concept is used to analyze crack propagation.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Delaminations, Energy release rate, Fatigue, Intralaminar cracks, Monte Carlo method, Quasi-static loading, Weibull distribution
National Category
Applied Mechanics
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-90827 (URN)10.1016/B978-0-12-822944-6.00020-7 (DOI)978-0-12-803581-8 (ISBN)
Available from: 2022-05-31 Created: 2022-05-31 Last updated: 2022-05-31Bibliographically approved
Al-Maqdasi, Z., Sott, R., Mattsson, C., André, A. & Joffe, R. (2022). Performance of recycled glass fibers from composite parts by different treatments. In: Vassilopoulos, Anastasios; Michaud, Véronique (Ed.), ECCM 2022 - Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability. Paper presented at 20th European Conference on Composite Materials (ECCM20), Lausanne, Switzerland, June 26-30, 2022 (pp. 77-84). Lausanne: EPFL Lausanne, Composite Construction Laboratory, 6
Open this publication in new window or tab >>Performance of recycled glass fibers from composite parts by different treatments
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2022 (English)In: ECCM 2022 - Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability / [ed] Vassilopoulos, Anastasios; Michaud, Véronique, Lausanne: EPFL Lausanne, Composite Construction Laboratory , 2022, Vol. 6, p. 77-84Conference paper, Published paper (Other academic)
Abstract [en]

In this work, glass fibers have been retrieved from decommissioned composite parts by three different methods. Namely, (i) pyrolysis, (ii) a novel solvolysis and (iii) a combination of solvolysis followed by pyrolysis. The techniques allowed successful recovering of sufficiently long fiber bundles (> 30 mm) that enabled separating single fibers for manual handling and testing. Single fiber tensile tests were performed to evaluate the efficiency of different recovery methods to preserve properties in comparison to the virgin fibers. The mechanical test results revealed that the stiffness of the recovered fibers has not been affected by the treatments. On the other hand, around 45% of the fiber’s strength was retained after the solvolysis process which is a comparable value to that found in literature. 

Place, publisher, year, edition, pages
Lausanne: EPFL Lausanne, Composite Construction Laboratory, 2022
Keywords
Glass fiber, recovery, solvolysis, pyrolysis, mechanical properties
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-96167 (URN)10.5075/epfl-298799_978-2-9701614-0-0 (DOI)2-s2.0-85149360317 (Scopus ID)978-2-9701614-0-0 (ISBN)
Conference
20th European Conference on Composite Materials (ECCM20), Lausanne, Switzerland, June 26-30, 2022
Funder
Vinnova, 2018-04132
Available from: 2023-03-16 Created: 2023-03-16 Last updated: 2023-05-15Bibliographically approved
Nunes, S., Joffe, R., Emami, N., Fernberg, P., Saseendran, S., Esposito, A., . . . Varna, J. (2022). Physical aging effect on viscoelastic behavior of polymers. Composites Part C: Open Access, 7, Article ID 100223.
Open this publication in new window or tab >>Physical aging effect on viscoelastic behavior of polymers
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2022 (English)In: Composites Part C: Open Access, ISSN 2666-6820, Vol. 7, article id 100223Article in journal (Refereed) Published
Abstract [en]

The effect of physical aging on the viscoelastic (VE) behavior of epoxy resin is investigated experimentally performing strain-controlled tests at various temperatures on specimens aged at different temperatures (TA) for different times (tA). The aging effect is analyzed using as a framework Schapery's type of thermo-aging-rheologically simple (T-A-R simple) VE model that contains aging-state and test-temperature dependent shift factor. Experiments show that in first approximation, the shift factor can be presented as the product of aging related shift factor aA and temperature related factor aT. It is found that for short aging times the change rate of the aging shift factor with tA does not depend on TA, whereas for long tA at high TA the rate increases. Shift factors alone are not able to explain differences in relaxation curves for almost “fully” aged specimens aged at different high TA, It is shown that a T-A-R complex VE model with two additional aging-dependent functions can describe the observed discrepancies.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Physical aging, Viscoelasticity, Shift factors, Numerical analysis
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-88621 (URN)10.1016/j.jcomc.2021.100223 (DOI)000819159600009 ()2-s2.0-85121922581 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-01-01 (johcin)

Available from: 2021-12-30 Created: 2021-12-30 Last updated: 2023-09-06Bibliographically approved
Al-Maqdasi, Z., Joffe, R. & Emami, N. (2022). Synergistic Effect of Multiscale Reinforcement on Wear of Wood Polymer Composites. In: PolyTrib 2022: . Paper presented at 4th International Conference on Polymer Tribology, December 5-6 2022, Stockholm, Sweden (pp. 34-35).
Open this publication in new window or tab >>Synergistic Effect of Multiscale Reinforcement on Wear of Wood Polymer Composites
2022 (English)In: PolyTrib 2022, 2022, p. 34-35Conference paper, Oral presentation with published abstract (Other academic)
Keywords
nanocomposites, Tribology, parameters, mechanical performance
National Category
Composite Science and Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-96170 (URN)
Conference
4th International Conference on Polymer Tribology, December 5-6 2022, Stockholm, Sweden
Available from: 2023-03-16 Created: 2023-03-16 Last updated: 2024-01-12Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5210-4341

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