Novel stiffeners exploiting internal pressurisation to enhance buckling behaviour under bending loads

• A novel thin-walled stiffener exploiting internal pressurisation is proposed.
• Pressure significantly increases the stiffener's buckling load under bending.
• Pressure may lead to a different buckling mode.
• It exhibits higher bearing load capacity per mass unit than the one of a single pipe.
• A novel possible application in the field of aerospace engineering is presented.

The paper proposes a novel type of stiffener designed to bear bending loads by exploiting internal pressure effects. The stiffener is made of two adjacent thin-walled pipes (r/t≥50)(r/t≥50) jointed with a connecting strip. Such a structure is shown to have higher performance against buckling failure compared to a single pipe and its geometry allows for good exploitation of internal pressurisation.The study is conducted by using the FEA software ANSYS and the analysis technique is the linear perturbation buckling analysis. Internal pressure ranges from 0 to 1.4 MPa. The buckling mechanisms are observed for a set of models with different values of length, wall thickness and geometric variation of the cross-section. It is shown that two different buckling modes can take place. However, for a given geometry, the level of pressure can alter the behaviour and lead to one mode rather than the other one.Potential of the presented structure is maximised by the use of high performance materials and a possible aerospace engineering application is presented.