In order to improve the tribological properties of calcium sulfonate complex–polyurea grease, WS₂ nanoparticles were used as additives to prepare WS₂ calcium sulfonate complex–polyurea grease. The tribological behavior of WS₂ grease on the GCr15 surface was systematically studied. The results indicate that WS₂ nanoparticles can significantly improve the extreme pressure performance of calcium sulfonate complex–polyurea grease. When the concentration of WS₂ nanoparticles is 2 wt.%, the friction coefficient decreases by 14.94%, and the maximum nonseizure load PB increases by 31.41%. As the temperature increases, the friction coefficient and wear rate of WS₂ grease first decrease and then increase. This is mainly attributed to the adsorption and frictional chemical reaction between WS₂ nanoparticles and the matrix.

To expand the applications of polymer friction modifiers in low viscosity oils suitable for hybrid power systems, the tribological properties of five kinds of oil samples at different temperatures were studied, which were compounded with polymer friction modifiers Perfad XG 2500, molybdenum dialkyl dithiocarbamate (MoDTC), zinc dialkyl dithiophosphate (ZDDP). When Perfad XG 2500 is used alone, it forms a brush-like surface film at low temperatures, which can provide lower initial friction. With the rise in temperature, its antifriction effect decreases significantly, which is related to the desorption behavior of physical film. When Perfad XG 2500 is combined with MoDTC, it has the best synergistic antifriction effect, and the average friction coefficient is reduced by a maximum of 20.83% (90 °C). Its friction coefficients decrease significantly with the increase in temperature due to the dissociation process of MoDTC catalyzed by high temperature. However, there are many furrows on the worn surfaces, and the sharp features of the profiles are obvious. When Perfad XG 2500 is combined with ZDDP, it has the best synergistic anti-wear effect, and the total wear depth is reduced by 49.6%. Its worn surface is smooth and defect-free, with minimal residual strain. The friction coefficients are hardly affected by temperature, and the average friction coefficient is reduced by a maximum of 14.4% (30 °C). When Perfad XG 2500, MoDTC and ZDDP are used together, the average friction coefficient is reduced by up to 15.2% (30 °C). Its friction coefficient increases slightly with the rise in temperature. The reason for its moderate tribological performance may be related to the superficial competition of various additives.

With the aim of improving the tribological properties of low-viscosity gear oil for automobiles, an acrylate of dialkyl dithiophosphoric acid (ADDP) with strong polar groups was synthesized. The tribological behavior of ADDP combined with molybdenum dialkyl dithiocarbamate (MoDTC) in gear oil was systematically studied. Tribological performances of gear oil containing different additives were assessed using a four-ball friction and wear tester. The obtained tribological characteristics reveal that ADDP and MoDTC can significantly improve the antiwear and antifriction performance of low-viscosity gear oil. Moreover, compared with using MoDTC or ADDP alone, the average friction coefficient and wear scar diameter of ADDP combined with MoDTC further decreased by 2.41–19.15% and 5.00–18.19%, respectively. Analysis of the worn surface showed that the structural characteristics and physical synergistic lubricating actions of the ADDP with MoDTC additives during the friction process can contribute to the exceptional tribological properties of the hybrid additives.

To investigate the effect of erucamide on the tribological properties of GCr15 steel, polyurea grease is prepared with different concentration of erucamide as additive. The tribological behavior of erucamide on the surface of GCr15 steel is studied by reciprocating friction test. The results show that 1.5wt.% erucamide has the best tribological property and the friction-induced vibration and noise suppression capability, which is attributed to the formation of lubricating film on the transition region of the friction surface, which maintains the friction in a relatively stable state, and the maximum thickness of lubricating film is 3.91 μm.

The present study investigates the effect of friction parameters on tribological properties of erucamide as an additive in grease on GCr15 steel, as well as the sensitivity of erucamide to these parameters. An orthogonal test design is utilized to sample the friction parameters, followed by the construction of a Kriging model to articulate the relationship between these parameters and the designated objectives (average friction coefficient and wear volume). The Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used to optimize the design objectives and verify the accuracy of the model. The Monte Carlo method is used to analyze the sensitivity of erucamide to the friction parameters. The results showed that erucamide exhibits excellent tribological properties at 80 N/20 Hz/25 °C and 20 N/20 Hz/25 °C. The sensitivity of erucamide to friction parameters from high to low is temperature, load, and speed. This can be ascribed to erucamide's unique structure, encompassing a globular aggregation head and a hydrophobic tail extending outward. The anti-friction effects and lubrication properties of erucamide are driven by its rheological properties and intermolecular interactions. At elevated temperatures, erucamide's fluidity escalates, favoring the lubricating film formation; however, excessive fluidity may impede its adherence to requisite locations, thereby resulting in compromised tribological properties of erucamide at high temperatures.

In the realm of van design, researchers have been diligently working to enhance rollover crashworthiness while concurrently achieving lightweight body structures. Unlike front and side impacts, rollover crashworthiness is impacted by a greater number of structural dimensions and material parameters. As such, this paper implements an unreplicated saturated factorial design to conduct factor screening for vehicle rollover crashworthiness. This approach effectively and accurately resolves the screening challenges that arise from large numbers of factors, and eliminates dependence on traditional design experience. Consequently, it shortens the design cycle and reduces development costs. In addition, this paper establishes four Kriging approximate models that describe the specific energy absorption and total mass of the key body structure, the displacement of the roof, and the maximum angular velocity of the body’s center of mass. To address the multi-objective optimization problem of improving rollover crashworthiness while reducing mass, this paper combines the particle swarm optimization algorithm with the artificial immune algorithm. This hybrid algorithm converges rapidly, and the Pareto solution set exhibits superior uniformity and diversity. Finally, the shortest distance method is employed to identify the optimal design scheme that can enhance the rollover crashworthiness of vans and reduce the mass of body parts.