The gear shaft needs to measure its radial runout for straightening before finishing, while it is difficult to measure the gear shaft radial runout without rotating the gear shaft by the existing measurement technology, which results the measurement inefficient. Present work puts forward a method of measuring a gear shaft radial runout with line structured light vision. This method can measure the radial runout value and direction online for straightening the bending of the gear shaft. The center position of the gear shaft cross section is obtained by the ellipse geometric fitting on the laser plane to eliminate the influence of projection distortion. The measurement method is tested by a specialized experiment, and the experimental results show that measurements of the method meet the requirements of straightening the gear shaft. The method can realize online measurement of the gear shaft radial runout just by a single image without rotating the gear shaft, so it features fast measurement compared with the existing measurement technology.

Shape memory alloys (SMAs) are proved to have high energy-to-volume ratio and large displacement. However, they have the defect of longer recovery time. In practice, designing SMA wire actuators is a very complex and exhausted thing because of extensive and various needs. In this study, a special setup was designed, which can test many characteristics of a SMA wire heated by electric current, including temperature, deformation, response time, recovery time, wind speed (for cooling), and load. Besides, an empirical model of the wires temperature was presented for avoiding overheating the wires. By fitting experiment data, unknown parameters in this model are determined. Next, main design parameters are investigated on how they exert effects on the characteristics of the SMA wires, including wire radius, convection type, load, and voltage. At last, the time response characteristics were also analyzed. Through this study, one can make clear how each design parameter plays its part in SMA wire actuators.

The aim of the present paper is to study experimentally and numerically the frictional behaviour of engineering surfaces within all lubrication regions of point contacts. For this reason, a numerical solution proposed elsewhere by the current authors, which can predict friction under the different lubrication modes of elastohydrodynamic, mixed, and boundary lubrications, is introduced. Based on a deterministic model of mixed lubrication, the solution was combined with the variation of the lubricating films’ physical state during the transition of lubrication modes. Results show that roughness amplitude has a great effect on the transition of friction regimes. In addition, it is also observed that variation of the friction coefficient has nearly the same trend as the true contact area ratio in the mixed lubrication state. Meanwhile, it is concluded that transverse roughness has better film-forming capacity than longitudinal roughness and thus leads to a lower magnitude of friction coefficient if the operating conditions are the same. Analysis of the mechanism of friction behaviour suggests that the true contact area ratio determines the friction behaviour of engineering surfaces in mixed lubrication. In smooth contacts, the comparison of experiment tests and simulation results suggests that friction variation results from gradual change of the liquid lubricant to solid-like matter with diminishing film thickness.

This work focuses on practical solution to designing interference fit joint. For this, based on a series of analytical expressions, we studied structural effects on performances of shaft-hub interference fit assembly when the interference range remains unchanged. The results suggest that the contact stress gets lower with thinner hub and increasing fit diameter. Furthermore, the hub thickness has little effect on the strength of hub. Thicker hub shows larger contact stiffness while enhancing fit diameter can reduce contact stiffness. Too large radius of rounded edge has little effect on stress concentration of the assembly. The study provides a rapid and effective method of interference connection design for engineering.

Disc brakes are widely used in various kinds of light vehicles. Currently, it has become a tendency to reduce the mass and volume of brake systems because of the increasing lightweight requirement for vehicles, especially for passenger vehicles in populated cities and for outdoor sport. However, there is often conflict between light weight and reliability. In this article, the braking characteristics of a thin disc brake were investigated experimentally, using a self-developed inertia braking platform. The platform was designed to conveniently measure multifield characteristics in real time. The goal of the experiment is to verify the special performance of a brake system with a very thin solid disc. Measurements of transient temperature, lateral vibration, and noise in the dry friction contacts of a steel solid thin disc and two resin circular pads were performed. A frequency–time analysis method was used for the lateral vibration of the disc and braking noise. The results suggest that one of the reasons for lateral vibration is the mounting error of the thin disc–shaft system, which should receive extra attention for safety reasons. In addition, the braking noise is structural borne.

This paper presents a modular, assemblable mortice-and-tenon load-bearing structure with variable stiffness, driven by embedded electrically controlled shape memory alloy (SMA) wires functioning as tendons within a tensegrity system. The study addresses three key aspects: modular design, topology optimisation of tree-like configurations, and active stiffness control through voltage-regulated contraction of the SMA wires. A variable stiffness component utilising the shape memory effect of SMA is proposed. In each unit, electrically controlled SMA wires serve as tendons and are connected via universal joints, enabling two-degree-of-freedom rotation. By coordinating the contraction of multiple SMA wires, both the stiffness and spatial orientation of the module can be adjusted, facilitating stiffness-tunable control across various spatial configurations. Geometric and mechanical theoretical models are established for the variable stiffness components and topological configurations. Experimental results validate the geometric models and confirm the effectiveness of the stiffness modulation. This work presents a design methodology for assemblable mortice-and-tenon variable stiffness structures actuated by embedded SMA wires. The proposed approach offers an efficient means for active stiffness–flexibility transformation and holds promise for applications such as flexible robotic joints and intelligent suspension systems.