Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 30) Show all publications
Pakkam Gabriel, V. R., Petkov, V. I., Fernberg, P. & Varna, J. (2024). Effect of heat treatment and test temperature on transverse cracking in tensile loading. Composites. Part A, Applied science and manufacturing, 181, Article ID 108149.
Open this publication in new window or tab >>Effect of heat treatment and test temperature on transverse cracking in tensile loading
2024 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 181, article id 108149Article in journal (Refereed) Published
Abstract [en]

Accumulation of transverse cracks in carbon fiber heat resistant polymer (with bismaleimide formulation) cross-ply laminates during tensile loading at elevated temperatures and after long heat treatment is analysed. Data shows that both the iso-thermal heat treatment and testing at elevated temperatures reduce the transverse cracking resistance. A two-parameter Weibull failure stress distribution model with scale parameter degrading with heat treatment and elevated temperature is used for crack initiation analysis. The degradation is described by polynomial expansion including interaction terms. Data shows that the scale parameter dependence on the heat treatment time and the test temperature is rather linear. The same expansion parameters have been successfully used for laminates with the same constituents but with a different layup and fiber content.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Polymer matrix composite, Transverse cracking, Statistical methods, CT analysis
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-104370 (URN)10.1016/j.compositesa.2024.108149 (DOI)2-s2.0-85188665648 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-04-12 (signyg);

Funder: Swedish Aeronautical Research Program NFFP 7 [project number 2019-02777]; Swedish Aeronautical Research Program NFFP 8 [project 2023-01199]; GKN Aerospace Sweden AB;

Full text license: CC BY

Available from: 2024-02-23 Created: 2024-02-23 Last updated: 2024-05-14Bibliographically approved
Bianchi, O., Cruz, J. A., Paim, L., Lavoratti, A., Al-Maqdasi, Z., Amico, S. C., . . . Joffe, R. (2024). Rheology, curing and time-dependent behavior of epoxy/carbon nanoparticles systems. Journal of Applied Polymer Science, 141(3), Article ID e54821.
Open this publication in new window or tab >>Rheology, curing and time-dependent behavior of epoxy/carbon nanoparticles systems
Show others...
2024 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 141, no 3, article id e54821Article in journal (Refereed) Published
Place, publisher, year, edition, pages
John Wiley & Sons, 2024
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

Validerad;2024;Nivå 2;2024-04-04 (signyg);

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: 2024-04-04Bibliographically approved
Petkov, V. I., Pakkam Gabriel, V. R. & Fernberg, P. (2024). Semantic segmentation of progressive micro-cracking in polymer composites using Attention U-Net architecture. Tomography of Materials and Structures, 5, Article ID 100028.
Open this publication in new window or tab >>Semantic segmentation of progressive micro-cracking in polymer composites using Attention U-Net architecture
2024 (English)In: Tomography of Materials and Structures, ISSN 2949-673X, Vol. 5, article id 100028Article in journal (Refereed) Published
Abstract [en]

The present study delivers a methodology for investigating the gradual damage development in a carbon fibre-reinforced cross-ply polymer composite during a sequence of thermo-mechanical loadings with the help of X-ray computed tomography. The procedure allows an in-depth analysis of the occurrence and nature of the multiple cracks that form within layers oriented perpendicular, or transverse, to the loading direction. This is achieved by using Attention U-Net architecture for semantic segmentation of the transverse cracks. The model shows promising results, through an ability to identify all the transverse cracks and reflect the damage progression. The described method provides a robust routine for analysing challenging polymer composite tomographic datasets.

Keywords
Polymer composites, Micro-cracking, X-ray computed tomography, Image analysis, Deep learning, Attention U-Net
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-104991 (URN)10.1016/j.tmater.2024.100028 (DOI)
Projects
INTDEMO MOTOR
Funder
Vinnova, 2020-00188
Note

Godkänd;2024;Nivå 0;2024-04-08 (marisr);

Funder: KN Aerospace,Trollhättan, Sweden;

Full text license: CC BY

Available from: 2024-04-05 Created: 2024-04-05 Last updated: 2024-04-08Bibliographically approved
Forsberg, F., Fernberg, P., Al-Maqdasi, Z., Petkov, V., Lycksam, H. & Joffe, R. (2023). Efficient Use of Micro-Tomography for In-Depth Characterization of Composites. In: Brian G. Falzon; Conor McCarthy (Ed.), ICCM 2023 - Proceedings of the 2023 23rd International Conference on Composite Materials: . Paper presented at 23rd International Conference on Composite Materials (ICCM 2023), Belfast, United Kingdom, July 30-August 4, 2023. Queen's University Belfast, Northern Ireland
Open this publication in new window or tab >>Efficient Use of Micro-Tomography for In-Depth Characterization of Composites
Show others...
2023 (English)In: ICCM 2023 - Proceedings of the 2023 23rd International Conference on Composite Materials / [ed] Brian G. Falzon; Conor McCarthy, Queen's University Belfast, Northern Ireland , 2023Conference paper, Poster (with or without abstract) (Refereed)
Place, publisher, year, edition, pages
Queen's University Belfast, Northern Ireland, 2023
Series
ICCM International Conferences on Composite Materials
National Category
Applied Mechanics
Research subject
Experimental Mechanics; Polymeric Composite Materials; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-105053 (URN)2-s2.0-85187561369 (Scopus ID)
Conference
23rd International Conference on Composite Materials (ICCM 2023), Belfast, United Kingdom, July 30-August 4, 2023
Available from: 2024-04-11 Created: 2024-04-11 Last updated: 2024-04-11Bibliographically approved
Fernberg, P., Bru, T. & Joffe, R. (2023). Scrapped Composite Ice-Hockey Stick Shafts For Resuse in Crash Energy Absorbers. In: Brian G. Falzon; Conor McCarthy (Ed.), ICCM 2023 - Proceedings of the 2023 23rd International Conference on Composite Materials: . Paper presented at 23rd International Conference on Composite Materials (ICCM 2023), Belfast, United Kingdom, July 30-August 4, 2023. Queen's University Belfast, Northern Ireland
Open this publication in new window or tab >>Scrapped Composite Ice-Hockey Stick Shafts For Resuse in Crash Energy Absorbers
2023 (English)In: ICCM 2023 - Proceedings of the 2023 23rd International Conference on Composite Materials / [ed] Brian G. Falzon; Conor McCarthy, Queen's University Belfast, Northern Ireland , 2023Conference paper, Poster (with or without abstract) (Refereed)
Place, publisher, year, edition, pages
Queen's University Belfast, Northern Ireland, 2023
Series
ICCM International Conferences on Composite Materials
National Category
Mechanical Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-105055 (URN)2-s2.0-85187575571 (Scopus ID)
Conference
23rd International Conference on Composite Materials (ICCM 2023), Belfast, United Kingdom, July 30-August 4, 2023
Projects
RE:Source
Funder
Swedish Research Council FormasSwedish Energy AgencyVinnovaLuleå University of Technology
Available from: 2024-04-11 Created: 2024-04-11 Last updated: 2024-04-11Bibliographically approved
Petkov, V., Fernberg, P. & Solano, C. (2022). Assessment of the Properties of two High-Temperature Thermosetting Polyimides. In: Vassilopoulos, Anastasios P.; 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. 8-15). EPFL Lausanne, Composite Construction Laboratory, 6
Open this publication in new window or tab >>Assessment of the Properties of two High-Temperature Thermosetting Polyimides
2022 (English)In: ECCM 2022 - Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability / [ed] Vassilopoulos, Anastasios P.; Michaud, Véronique, EPFL Lausanne, Composite Construction Laboratory , 2022, Vol. 6, p. 8-15Conference paper, Published paper (Other academic)
Abstract [en]

A novel thermosetting polyimide, NEXIMID R300, is introduced and compared with the commercial MHT-R in terms of fracture toughness, thermal properties and ageing behaviour. The new R300 formulation has an altered chemical composition compared to the MHT-R, resulting in a reduced cross-linking density, and was presented as a less susceptible to cracking and a more processable alternative during composite manufacturing with resin transfer moulding. The study uses fracture toughness with single edge notched beam setup, DSC, dilatometry, weight loss measurements and optical microscopy for investigation of the neat resin properties of both material. A slight increase in fracture toughness and a decrease in glass transition temperature for the R300 formulation is observed.

Place, publisher, year, edition, pages
EPFL Lausanne, Composite Construction Laboratory, 2022
Keywords
Ductile fracture, Glass transition, Polyimides, Resin transfer molding, Resins, Thermosets, Ageing behavior, Chemical compositions, Composite manufacturing, Cross-linking density, DSC, Highest temperature, Processable, Property, Resin-transfer molding, Thermosetting polyimides, Fracture toughness
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-96908 (URN)2-s2.0-85149412073 (Scopus ID)
Conference
20th European Conference on Composite Materials (ECCM20), Lausanne, Switzerland, June 26-30, 2022
Note

ISBN för värdpublikation: 978-2-9701614-0-0

Available from: 2023-05-15 Created: 2023-05-15 Last updated: 2023-05-15Bibliographically approved
Petkov, V. I. & Fernberg, P. (2022). Damage development during thermal ageing in carbon fibrereinforced polyimide composites. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>Damage development during thermal ageing in carbon fibrereinforced polyimide composites
2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-95091 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2022-12-30 Created: 2022-12-30 Last updated: 2023-01-04Bibliographically approved
Nunes, S. G., Al-Maqdasi, Z., Fernberg, P., Amico, S. C. & Varna, J. (2022). Does the viscoelastic behavior of fully cured epoxy depend on the thermal history during curing?. Journal of composite materials, 56(22), 3439-3453
Open this publication in new window or tab >>Does the viscoelastic behavior of fully cured epoxy depend on the thermal history during curing?
Show others...
2022 (English)In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 56, no 22, p. 3439-3453Article in journal (Refereed) Published
Abstract [en]

Residual strains and shape distortions in a polymer-based composite structure may depend on the cure schedule used for manufacture. Aiming to understand the cure history effects, the influence of the curing “path” (time tc and temperature Tc path during curing) on viscoelastic (VE) response of a fully cured (FC) (alpha = 0.992) epoxy was investigated. Five different “families” of the same epoxy were manufactured in constraint-free conditions using different sets of curing parameters. Then, tensile tests were performed at different temperatures (T = 30 to 110 °C), and the time-temperature superposition principle (TTSP) and Schapery’s type of linear viscoelastic (VE) model, accounting for physical aging of specimens tested at high temperature, were used. The results show that the VE properties of the studied epoxy are independent of the curing history provided that at the end all specimens are fully cured. Also, the physical aging rate at high temperatures of all “families” is the same and it can be described by a simple aging-temperature independent equation reported in Nunes et al1 It is expected that curing history of unconstrained and fully cured epoxy has an insignificant effect on final viscoelastic behavior, a knowledge which could assist in developing more time and cost-efficient cure cycles.

Place, publisher, year, edition, pages
Sage Publications, 2022
Keywords
epoxy, curing history, viscoelasticity, physical aging, shift factors, simulations
National Category
Other Materials Engineering
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-92323 (URN)10.1177/00219983221115850 (DOI)000826103600001 ()2-s2.0-85134535047 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-09-26 (hanlid);

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

Available from: 2022-07-29 Created: 2022-07-29 Last updated: 2022-09-26Bibliographically approved
Pakkam Gabriel, V. R. & Fernberg, P. (2022). Fatigue Damage Model of High Temperature Polymer Composites in Aero-Engines. In: ICAS Proceedings 33rd Congress of the International Council of the Aeronautical Sciences, Stockholm, Sweden: . Paper presented at 33rd Congress of the International Council of the Aeronautical Sciences, Stockholm, Sweden, September 4-9, 2022 (pp. 3805-3812). The International Council of the Aeronautical Sciences, 5
Open this publication in new window or tab >>Fatigue Damage Model of High Temperature Polymer Composites in Aero-Engines
2022 (English)In: ICAS Proceedings 33rd Congress of the International Council of the Aeronautical Sciences, Stockholm, Sweden, The International Council of the Aeronautical Sciences , 2022, Vol. 5, p. 3805-3812Conference paper, Published paper (Refereed)
Abstract [en]

High Temperature Polymer Cross-ply (HTPC) laminate specimens are subjected to tension-tension fatigue loading at 3 different maximum stress levels at room temperature. Transverse cracking in 90° layer in the crossply laminate upon fatigue tests is analyzed. Based on probabilistic approach, using Weibull distribution, a prediction model for the increase in number of transverse cracks upon fatigue loading at different stress levelsis developed. The predicted crack density (number of cracks per unit length) development shows good agreement with the test results for fatigue at the higher stress levels considered. A slight overprediction is observed at lowest stress level.

Place, publisher, year, edition, pages
The International Council of the Aeronautical Sciences, 2022
Keywords
High temperature polymer composite, fatigue loading, Weibull distribution, transverse cracks
National Category
Composite Science and Engineering Applied Mechanics
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-95486 (URN)2-s2.0-85159612676 (Scopus ID)
Conference
33rd Congress of the International Council of the Aeronautical Sciences, Stockholm, Sweden, September 4-9, 2022
Note

Funder: Swedish Aeronautical Research Program/Nationella flygtekniska forskningsprogrammet (NFFP7) (2019-02777)

Available from: 2023-02-02 Created: 2023-02-02 Last updated: 2023-06-01Bibliographically approved
Pakkam Gabriel, V. R., Loukil, M. S., Fernberg, P. & Varna, J. (2022). Methodology for transverse cracking simulation in 90 plies of composite laminate under fatigue loading. In: Vassilopoulos, Anastasios P.; 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. 16-22). EPFL Lausanne, Composite Construction Laboratory, 6
Open this publication in new window or tab >>Methodology for transverse cracking simulation in 90 plies of composite laminate under fatigue loading
2022 (English)In: ECCM 2022 - Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability / [ed] Vassilopoulos, Anastasios P.; Michaud, Véronique, EPFL Lausanne, Composite Construction Laboratory , 2022, Vol. 6, p. 16-22Conference paper, Published paper (Other academic)
Abstract [en]

Methodology for crack density evolution simulation in tension-tension fatigue and parameter determination in a model that relies on failure stress distribution (Weibull) in the 90 ply is presented. Cyclic loading is performed at one stress level to obtain detailed crack density dependence on the number of cycles. In addition, one data point (crack density at specified number of cycles) is necessary at a different stress level. Non-interactive crack density region is used to determine Weibull parameters. Then, crack density in a whole crack density range and for arbitrary stress level is predicted using the obtained Weibull parameters, the Monte Carlo method for failure stress distribution and a novel model for stress distribution between cracks. The predictions are in good agreement with test results.

Place, publisher, year, edition, pages
EPFL Lausanne, Composite Construction Laboratory, 2022
Keywords
Intralaminar cracking, Weibull parameter determination, Shape parameter, Scale parameter, Fatigue loading, Failure stress, Monte Carlo simulation
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-90131 (URN)2-s2.0-85149406235 (Scopus ID)
Conference
20th European Conference on Composite Materials (ECCM20), Lausanne, Switzerland, June 26-30, 2022
Projects
Swedish Aeronautical Research Program (NFFP7)
Note

Funder: Swedish Aeronautical Research Program (NFFP7) (2019- 02777);

ISBN för värdpublikation:  978-2-9701614-0-0

Available from: 2022-04-10 Created: 2022-04-10 Last updated: 2023-09-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5948-7525

Search in DiVA

Show all publications