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The Influence of Material Configuration of Fibre-Metal Laminates with Alumina Core on Flexural Strength

Fatigue of Aircraft Structures
Volume 2022 (2022): Issue 14 (December 2022)
By:
Open Access
|Nov 2023

Figures & Tables

Figure 1.

Diagram of the process of forming an analysed FML (InverTec laminate). FMLs, fibre metal laminates; FRP, fibre-reinforced polymer.
Diagram of the process of forming an analysed FML (InverTec laminate). FMLs, fibre metal laminates; FRP, fibre-reinforced polymer.

Figure 2.

Scheme of the three-point bend test.
Scheme of the three-point bend test.

Figure 3.

Results of the static three-point bend tests presented by flexural stress vs. displacement graphs, for specimens’ series: S1 (A), S2 (B), S3 (C) and S4 (D).
Results of the static three-point bend tests presented by flexural stress vs. displacement graphs, for specimens’ series: S1 (A), S2 (B), S3 (C) and S4 (D).

Figure 4.

Results of the static three-point bend test: values of flexural stress (A) and displacement to failure (B).
Results of the static three-point bend test: values of flexural stress (A) and displacement to failure (B).

Figure 5.

Views of the damage of specimens caused by the bending test for series: S1_0 (A), (B), S1_90 (C), (D), S2_0 (E), (F), S2_90 (G), (H).
Views of the damage of specimens caused by the bending test for series: S1_0 (A), (B), S1_90 (C), (D), S2_0 (E), (F), S2_90 (G), (H).

Figure 6.

Results of the fatigue test for S1_0 series specimens. (A) S-N curve and (B) flexural stress–time curve.
Results of the fatigue test for S1_0 series specimens. (A) S-N curve and (B) flexural stress–time curve.

Figure 7.

Results of the fatigue test for S2_0 series specimens: (A) S-N curve and (B) flexural stress-time curve.
Results of the fatigue test for S2_0 series specimens: (A) S-N curve and (B) flexural stress-time curve.

Figure 8.

Views of the fatigue damage of the specimen series 2 occurred after 130,000 cycles.
Views of the fatigue damage of the specimen series 2 occurred after 130,000 cycles.

Results of the fatigue bend test of the S2_0 series specimen

S2_0
No.Amplitude (mm)Max. fatigue flexural stress (MPa)% of flexural stressMin. fatigue flexural stress (MPa)% of flexural stressNumber of cycles
14,04−508,6357.93−203.8123.21183,521
24,19−539,3761.43−219.8025.0378,751
34,04−549,7262.61−220.7825.14131,413
44,04−479,3154.59−139.8215.921,000,000
54,03−543,9061.94−220.6625.13132,752
64,04−496,0856.50−166.2918.941,000,000

Configuration of the analysed series of FMLs

SeriesConfiguration of FRP laminate layersLaminate code
S1_03x PA6-GF60[0G/90G/0G/Alu]s
S1_903x PA6-GF60[90G/0G/90G/Alu]s
S2_03x PA6-GF60[0G3/Alu]s
S2_903x PA6-GF60[90G3/Alu]s
S3_01x PA6-CF60/4x PA6-GF60[0C/0G4/Alu]s
S3_901x PA6-CF60/4x PA6-GF60[90C/90G4/Alu]s
S4_01x PA6-CF60/4x PA6-GF60[0C/90G/0G/90G/0G/Alu]s
S4_901x PA6-CF60/4x PA6-GF60[90C/0G/90G/0G/90G/Alu]s

Results of the fatigue bend test of the S1_0 series specimen

S1_0
No.Amplitude (mm)Max. fatigue flexural stress (MPa)% of flexural stressMin. fatigue flexural stress (MPa)% of flexural stressNumber of cycles
14,04–245.6144.69−35.116.391,000,000
24,04−346.3063.01−99.7818.16396,453
34,02−365.0666.42−102.8518.71335,125
44,03−254.2246.25−37.516.861,000,000
54,03−261.5547.59−39.357.161,000,000
64,04−332.2160.45−90.4416.45452,144

Parameters of variothermal consolidation of InverTec inverted laminate sheets

Pressure (bar)Temperature (°C)Time (min)
Heating and plasticising of polymer matrix202606.5
Consolidation of the FRP composite302603.5
Cooling phase and solidification of the polymer melt306016.5

Comparison of the static and fatigue flexural strength of the Invertec, CARALL and CAPPAL FMLs

Type of FMLInverTec FMLCARALLCAPPAL*
S1_0S2_0Case 1 Bellini et al. (2019)Case Zopp et al. (2019)
Static flexural strength (MPa)506 ±20878 ±43644–734645 ±16
Fatigue flexural strength (max. number of cycles)106 cycles, up to 7% max flexural stress106 cycles, up to 19% flexural stressn.d.106 cycles, up to 32% maximum force of bending test
DOI: https://doi.org/10.2478/fas-2022-0003 | Journal eISSN: 2300-7591 | Journal ISSN: 2081-7738
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Language: English
Page range: 18 - 28
Published on: Nov 28, 2023
Published by: Institute of Aviation
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
fibre-metal laminates,
flexural strength,
fatigue,
composite materials
Related subjects:
Engineering,
Introductions and overviews,
Engineering, other

© 2023 Mariusz Frankiewicz, Michał Karoluk, Robert Dziedzic, Tristan Timmel, Peter Scholz, published by Institute of Aviation
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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