An optimized bio-inspired thin-walled structure with controllable crashworthiness based on magnetorheological fluid

In order to overcome the traditional thin-walled tubes' shortcomings of fixed crashworthiness and poor environmental adaptability, a magnetorheological bionic energy-absorbing element (MBEE) inspired by the horsetail structure was proposed and applied to design of thin-walled tubes in achieving variable and controllable crashworthiness. Theoretical analysis, numerical analysis, and optimization were conducted to perform in-depth study toward improving crashworthiness and associated controllability of the MBEE. In theoretical analysis, the theoretical models of total energy-absorption and crashworthiness' controllability were developed. In numerical analysis, a compression of MBEE under a constant loading speed was simulated using a finite element (FE) software and simulation results showed that: (1). differences on the total energy-absorption of magnetorheological fluid and structural framework in the compression of the MBEE predicted by FE simulation and theoretical model were only 3.49% and 2.16%, respectively. (2). the controllability of the MBEE's crashworthiness was up to 27.73% at the beginning of compression, but decreased to 12.29% when the total length of MBEE was compressed by nearly 67%. (3). the controllability of the MBEE's crashworthiness predicted by theoretical model and simulation also had high consistency. Finally, the parametric study and optimization were conducted to obtain the MBEE with optimal cross-sectional geometric shape filled into the traditional 9-cell thin-walled tube. When compared with the traditional 9-cell thin-walled tube, the total energy-absorption of the tube filled by the optimal MBEE was increased by 251.16%, and the specific energy absorption (SEA) of its structural framework was increased by 58.66%. In addition, the initial controllability eta int of this filled tube's crashworthiness was up 22.24%.