Shock and vibration caused by mechanical motion bring huge potential threats to the service life and assembly reliability of mechanical systems. Rubber materials have been widely used in aircraft, trains, and other engineering fields, due to their excellent properties in shock and vibration absorption. This paper aimed to study the rubber ring buffer applied to a certain type of Chinese locomotive. Firstly, the finite element model was established and verified through experimental data. Based on the verified simulation model, the influence of the constitutive parameters (C01/C10 ratio height H and contour radius R) of the rubber ring on its energy absorption and peak crushing force under impact loading was studied in a numerical environment. Finally, the design of the experiment was carried out by the optimized Latin hypercube method, and the response surface model was established, which intuitively demonstrated the influence of the relevant parameters of the rubber ring on the change trend of the energy absorption and peak force. Based on the proxy model, the parameters that improve the crashworthiness of the rubber ring buffer were found quickly by the NSGA-II optimization algorithm, and the problems of a long calculation time and low optimization efficiency when using the conventional finite element method were avoided. The optimization results stated that when H = 107.57 mm and R = 85.70 mm, C01/C10 = 0.0571 of the energy absorption of the optimized buffer was increased by 59.03%, and the peak force was decreased by 14.37%, compared with the original structure. The optimized rubber ring buffer is expected to reduce the peak crushing force, enhance the energy absorption capacity, and mitigate the damage to the train system caused by shock and vibration.

Polymer coatings are commonly used to protect carbon steels from corrosion but they are susceptible to weathering and many of them have environmental concerns. Therefore, we studied the possibility of an environmentally favorable inorganic magnesium phosphate cement (MPC) coating for protecting mild steel. A formulation suitable for coating steel was developed by compositional modification [i.e., incremental replacement of dead-burned magnesia (MgO) with magnesium hydroxide (Mg(OH)2)] to a road-repair MPC. This modification yielded an acceptable working time and prevented pore formation at the coating-steel interface. Corrosion monitoring by linear polarization and electrochemical impedance spectroscopy for 14 days found that, the MPC coating substantially increased the linear polarization resistance (Rp) [e.g., day 1: (8.2 ± 1.7) × 103 (nadir value) vs. 495 ± 55 Ω cm−2] and charge transfer resistance (Rct) (e.g., day 1: 9.3 × 103 vs. 3.8 × 102 Ω cm−2). The coated steel underwent neutral sodium chloride (NaCl) salt spray for 2400 h without visible rusting. Immersion for 24 h in liquids simulating the pore fluid indicated that, passivation by the excess MgO in the coating was a major contributor to its anti-corrosive property. Tafel polarization in the liquids found that, corrosion current density (Icorr) followed the rank: 3.5% NaCl solution (6.0 µA cm−2) > 3.5% NaCl solution containing MgO (3.6 µA cm−2) > 3.5% NaCl solution containing fragmented MPC (1.7 µA cm−2), suggesting that a physical barrier effect and dissolved phosphate ions improved its protection. This study shows that, MPC coating is a promising durable and environmentally favorable anti-corrosive material for protecting steel structures in some applications.

When the train collides, the anti-climbing energy-absorbing structure suffers huge impact force, which results in obvious deformation and energy absorption. Through the study of collision test and accident, it is found that the anti-climbing energy-absorbing structure produces obvious instability phenomenon when the collision occurs, and the lateral head shaking or vertical head nodding movement is likely to lead obvious buckling deformation of the energy absorption structure, which greatly reduces the structural energy absorption effect and increases the risk of train climbing. The guide structure of the anti-climbing structure affects the deformation and energy absorption to a certain extent. Therefore, this paper establishes the finite element model of the trolley with anti-climbing energy absorption structure, and the model is verified by experiments. Based on the verified finite element model, the effects of the diameter [Formula: see text] and thickness [Formula: see text] of the guide tube, the gap [Formula: see text] between the inner and outer guide tube and the vertical offset [Formula: see text] of the trolley center of mass on the energy absorption, vertical and horizontal stability of the structure were studied. The results show that the trolley center of mass offset [Formula: see text], the diameter [Formula: see text] and the wall thickness [Formula: see text] of the guide tube have a large influence on the deformed energy absorption mode of the anti-climbing energy absorption structure and the stability of the trolley. In order to investigate the influence of the trolley center of mass offset [Formula: see text], the diameter [Formula: see text] and wall thickness [Formula: see text] of the guide tube on the anti-climbing energy absorption structure, the response surface (RS) model of the design of experiment (DOE) was used together with the finite element model (FEM) calibrated by the test. Finally, based on the established RS model, the multi-objective genetic algorithm (MOGA) is used for multi-objective optimization design. The results show that the amount of energy absorbed (EA) by the anti-climbing energy absorbing structure, and the mass of the guide tube [Formula: see text] cannot be optimized simultaneously. Finally, the optimization results provide a good design matrix for obtaining anti-climbing energy absorbing structures and recommendations with excellent performance in terms of crashworthiness of locomotive.