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In this paper, a new type of honeycomb structure is proposed to enhance the energy absorption capacity for a honeycomb structure, and investigated its energy absorption efficiency (absorbed energy per unit volume) by finite element method (FEM). This model has small arc-shaped parts on the double cell wall, and can be manufactured by a similar way of standard honeycomb structures. Also, the proposed structure has large rigidity of plastic bending without increasing the mass. In this paper, effects of geometrical properties on the energy absorption characteristics are discussed.

In this study, the combination of an expansion tube and a deformable rigid tube with axial splitting is developed as a new mechanism for use as an impact energy absorber. The impact absorbing structure consists of two circular tube forming dies, with each die allowing the tube to expand and to split. The latter is used to remove away radially the debris after expansion and splitting, so that the absorption process can continue without being obstructed by the debris itself. This paper presents the experimental and theoretical investigation of the combined expansion tube-axial splitting as an impact energy absorber. The experiment by the laboratory scale impact testing has been done with a variation of the parameters such as pipe thickness ($t)$, angle of splitter ($\alpha )$, comparison of dies upgrading diameter ($D_2)$ and inner pipe diameter ($D_1)$ ($D_2$/$D_1)$. The theoretical investigation is carried out with a literature study related to the mechanics of material and theoretical studies from previous research studies. The final result of this paper, i.e. a new formula proposed to calculate the mean load, is reflective of the study of a combined expansion tube with axial splitting. The difference between the results of analytical calculation and experiments is 10.13%.

In this paper, the energy absorption behavior of a novel multibody circular tube is investigated based on the experimental and numerical methods. To achieve the best design for the segments, the bell-end circular tubes, a multi-objective optimization technique was implemented using Python and MATLAB with four various objective functions such as absorbed energy, mass, peak crush force, and average crush force. Moreover, an arrangement of these bell-end tubes as a multibody structure would decrease the total length, obtain less capacity usage, and have better crashworthiness characteristics. The results elucidate an enormous decrease in the peak crush force and an increase in specific absorbed energy in comparison with the thin-walled circular tubes having the same mass. Finally, the energy absorption behavior of the optimal multibody circular tube was tested and compared to the obtained numerical results in single and double forms.

Nested ring energy absorbers absorb most of the kinetic energy of an impact in an irreversible manner, reducing the damage to the human body or cargo inside the carrier in a collision. Compared to conventional single ring, nested ring can greatly increase the specific energy absorption (SEA) without significantly increasing the cost. This paper proposes a new design idea for the nested ring structure, which forms a new design by rotating the traditional configuration. Since the symmetry is broken, the deformation mode is asymmetric. Both experimental tests and finite element simulations are performed. The experimental results match the simulation results with less than 5% deviation, demonstrating the new design improves energy absorption capacity by 7% compared to previous nested ring designs.