First ever blended Straight-Fibre Variable Stiffness laminate
Aerospace application demonstrator of straight-fibre variable stiffness laminate
In 2019, Laminance co-founder Mohamed Gomaa designed and manufactured the first ever blended straight-fibre variable stiffness laminates. This achievement was part of MSc. thesis graduation work at the Delft University of Technology. In this same study, constant stiffness laminates with the same geometry were optimized for the same load case and manufactured. These highly optimized laminates were then tested in an experimental campaign and the results were then compared to conventional laminates.
This work brought years of research and theory to life. In addition to that, it highlighted the significant structural improvements that can be achieved with straight-fibre variable stiffness laminates.
Load Case
The variable stiffness design was achieved by optimizing a rectangular plate of 600mm x 400 mm subjected to a compression load. The design objective was to maximize the buckling load of the laminate. This is a typical load case scenario of upper skin panels of aircraft wings which are subjected to compressive loads as the wing bends upwards during flight.
Experimental results
The experimental results showed that the blended straight-fibre variable stiffness laminates can achieve a 94% increase in stiffness and an 81% higher buckling load when compared to their conventional constant stiffness counterparts.
| Structural Property | Units | Conventional Constant Stiffness | Blended SFVS | Improvement [%] |
| Stiffness | kN/mm | 46.09 | 89.30 | 94 |
| Buckling load | KN | 71.87 | 130.03 | 81 |
Blended laminate at compressive load of 71 kN
Conventional laminate at equal loading
Conclusion
In this experimental campaign straight-fibre variable stiffness laminates were used to design an upper wing skin panel. The physical demonstrator with similar weight showed an increased buckling performance of more than 80% in lab tests. These results substantiate the potential of the technology for application in the aviation industry.