Details
| Original language | English |
|---|---|
| Pages (from-to) | 665-683 |
| Number of pages | 19 |
| Journal | Journal of composite materials |
| Volume | 56 |
| Issue number | 5 |
| Early online date | 16 Dec 2021 |
| Publication status | Published - 1 Mar 2022 |
Abstract
The compressive strength of fiber reinforced composites is typically limited by a shear localization phenomenon known as microbuckling and is very sensitive to local imperfections of fiber alignment. Local misalignments act as randomly distributed flaws and introduce a dependence of the compressive strength on the size of material volume element under consideration. For homogeneously loaded material elements, weakest-link theory in combination with a Weibull power law is a frequently employed statistical model for microbuckling strength. This implies a dependence of strength on the size of volume under consideration. The present contribution investigates the strength–size relation for a non-crimp fabric via a numerical approach. Characteristics of the misalignment flaws used in simulations are derived from a comprehensive data set collected via large-scale measurements of roving dislocations on dry fiber material. Predictions resulting from the weakest-link Weibull theory are compared against strength–size statistics gathered by numerical analysis. In this manner, the size effects in single plies and laminates are quantified. The main findings are that weakest-link Weibull theory is well suited to predict size related strength loss in individual plies. However, it is also found that when plies are bonded to form laminates, misalignments in individual plies are mitigated in a way that is inconsistent with the weakest-link assumption. In all situations considered here, the strength loss expected from weakest-link Weibull theory was outweighed by a strength increase due to the mitigation effect when the volume was increased by adding extra layers to a laminate.
Keywords
- A polymer-matrix composites, B nonlinear behaviour, B strength, C buckling, C computational mechanics
ASJC Scopus subject areas
- Materials Science(all)
- Ceramics and Composites
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
- Materials Science(all)
- Materials Chemistry
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In: Journal of composite materials, Vol. 56, No. 5, 01.03.2022, p. 665-683.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - A numerical investigation of the statistical size effect in non-crimp fabric laminates under homogeneous compressive loads
AU - Daum, Benedikt
AU - Gottlieb, Gerrit
AU - Safdar, Nabeel
AU - Brod, Martin
AU - Ohlendorf, Jan Hendrik
AU - Rolfes, Raimund
N1 - Funding Information: Funding by the Deutsche Forschungsgemeinschaft (DFG, German research Foundation) - Projektnummer 329147126 is gratefully acknowledged. The authors thank Dr Andrea Miene/Faserinstitut Bremen for her support regarding measurements and image processing. Moreover, the authors thank Dr Clemens Hübler for advice regarding the statistical data analysis and Muzzamil Tariq for supporting experiments.
PY - 2022/3/1
Y1 - 2022/3/1
N2 - The compressive strength of fiber reinforced composites is typically limited by a shear localization phenomenon known as microbuckling and is very sensitive to local imperfections of fiber alignment. Local misalignments act as randomly distributed flaws and introduce a dependence of the compressive strength on the size of material volume element under consideration. For homogeneously loaded material elements, weakest-link theory in combination with a Weibull power law is a frequently employed statistical model for microbuckling strength. This implies a dependence of strength on the size of volume under consideration. The present contribution investigates the strength–size relation for a non-crimp fabric via a numerical approach. Characteristics of the misalignment flaws used in simulations are derived from a comprehensive data set collected via large-scale measurements of roving dislocations on dry fiber material. Predictions resulting from the weakest-link Weibull theory are compared against strength–size statistics gathered by numerical analysis. In this manner, the size effects in single plies and laminates are quantified. The main findings are that weakest-link Weibull theory is well suited to predict size related strength loss in individual plies. However, it is also found that when plies are bonded to form laminates, misalignments in individual plies are mitigated in a way that is inconsistent with the weakest-link assumption. In all situations considered here, the strength loss expected from weakest-link Weibull theory was outweighed by a strength increase due to the mitigation effect when the volume was increased by adding extra layers to a laminate.
AB - The compressive strength of fiber reinforced composites is typically limited by a shear localization phenomenon known as microbuckling and is very sensitive to local imperfections of fiber alignment. Local misalignments act as randomly distributed flaws and introduce a dependence of the compressive strength on the size of material volume element under consideration. For homogeneously loaded material elements, weakest-link theory in combination with a Weibull power law is a frequently employed statistical model for microbuckling strength. This implies a dependence of strength on the size of volume under consideration. The present contribution investigates the strength–size relation for a non-crimp fabric via a numerical approach. Characteristics of the misalignment flaws used in simulations are derived from a comprehensive data set collected via large-scale measurements of roving dislocations on dry fiber material. Predictions resulting from the weakest-link Weibull theory are compared against strength–size statistics gathered by numerical analysis. In this manner, the size effects in single plies and laminates are quantified. The main findings are that weakest-link Weibull theory is well suited to predict size related strength loss in individual plies. However, it is also found that when plies are bonded to form laminates, misalignments in individual plies are mitigated in a way that is inconsistent with the weakest-link assumption. In all situations considered here, the strength loss expected from weakest-link Weibull theory was outweighed by a strength increase due to the mitigation effect when the volume was increased by adding extra layers to a laminate.
KW - A polymer-matrix composites
KW - B nonlinear behaviour
KW - B strength
KW - C buckling
KW - C computational mechanics
UR - http://www.scopus.com/inward/record.url?scp=85121799273&partnerID=8YFLogxK
U2 - 10.1177/00219983211057346
DO - 10.1177/00219983211057346
M3 - Article
AN - SCOPUS:85121799273
VL - 56
SP - 665
EP - 683
JO - Journal of composite materials
JF - Journal of composite materials
SN - 0021-9983
IS - 5
ER -