Impact energy and deceleration at a certain time are the most influenced factor to passenger’s safety when collision between railway vehicles occurred. In this paper, forced external inversion mechanism is considered as impact energy absorber. This mechanism is selected due to its constant inversion load along uniform tube [5] and the impact force is reduced because of its inertia effect [7]. Material used as energy absorber is mild steel. Numerical analysis using finite element method is utilized to study the energy absorption capacity and deceleration characteristic of tube external inversion mechanism for complex transient problem of collision. The real scale experimental study is used to validate the numerical analysis by crashing a moving vehicle to static train series where the impact energy absorber module using external inversion mechanism is attached in the tip of static train series. Characteristic that consider in numerical and experimental study are deformation and contact force. The deformation differences between numerical and experimental study are under 9%. Whereas for contact force, the experimental result of contact force disposed under 8% of numerical result for velocity of moving train at 10 and 15 km/h.

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This paper reveals the mechanical behavior of thin-walled columns with pre-folded patterns subjected to compressive loading. The column specimens (Polylactic Acid) are fabricated using Fused Deposition Modeling 3D printer and subjected to quasi-static compressive loading to investigate their mechanical behavior (by modifying the specimens' cross-section patterns and folding angles). The column specimens are simulated by finite element analysis to understand how the stress distribution and local deformation affecting the stiffness, strength, and overall deformation. The experiments showed that introducing the pre-folded pattern in a thin-walled column with different cross-sections can dramatically lower its structural stiffness (85%) and compressive strength (69%), but increase its deformability (115%), which is good agreement with numerical simulation. The variation of cross-section patterns and pre-folding angle could effectively modify the compressive mechanical behavior. Moreover, the results demonstrate how the FDM 3D Printing method can be used in fabricating a thin-walled column with irregular shapes and then to modify its deformability. This finding can be useful for designing any complex structures requiring specific stiffness and deformation such as suspension devices, prosthetic devices in biomechanics, and robotic structures.