Thin-walled structure has a wide range of application in aerospace, energy and petrochemical, ocean engineering, automotive and other fields. We have carried out systematic research on the design methods and mechanical properties of thin-walled energy-absorbing structures, post-buckling thin-walled structures, and composite thin-walled structures. In addition, we have also pursued to assist the industry in related engineering applications.

1 Thin-walled Energy-absorbing Structures

The function of a energy-absorbing device is to irreversibly convert the kinetic energy during the impact process into the deformation energy, so as to achieve the purpose of protecting the carrier and personnel. In light of the origami design method, we have designed intricate three-dimensional structure, which has proved to effectively improve the mechanical performance.

A novel thin-walled tube was design with a pre-folded kite-shape rigid origami pattern as an energy absorber. The new structure was studied using numerical simulation and theoretical analysis under the quasi-static axial crushing, and shows a smooth and high reaction force curve, which results in more energy absorption and lower initial peak force in comparison with those of conventional square tubes. In the optimum case, an increase of 29.2% in specific energy absorption and a reduction of 56.5% in initial peak force were found in this new thin-walled tube.

Thin-walled tubes with a kite-shape rigid origami pattern

We designed a tubular thin-walled energy-absorbing structure pre-folded according to the diamond-shaped folding pattern, namely the origami crash box. Numerical simulations and experimental studies show that under quasi-static and low-speed impact loads, the pre-imbedded folds of the origami box can lead to a diamond-shaped deformation mode with high energy absorption efficiency, reaching a 20% reduction of the initial peak load and more than 50% increase in the Specific Energy Absorption (SEA). More importantly, the crushing form can be kept stable under different cross-sectional shapes and geometric parameters. In addition, a simplified theoretical model of the basic folding unit is established, revealing that the double-travel plastic hinge caused by the diamond-shaped mode is the main reason for the high SEA. Besides, the theoretical formula of the average compressive force is also derived.

A family of new origami crash boxes with rectangular, polygonal cross sections, and tapered shapes

2 Post-buckling Thin-walled Structures

A series of pre-embedded origami patterns are introduced to the thin-walled structures. Their elastic buckling process can be guided to a range of designed failure modes, which determines the exact post-buckling configuration. Meanwhile, the accuracy of the desired mode is examined experimentally. The energy formulation experimentally describes the driving mechanics of the buckling process and a bistable transition in the deformation. The pre-embedded technique can potentially be applied to other mechanical structures with different stiffness or under various boundary conditions.

Thin-walled structures with predictable buckling process