Impact damage, caused by low-energy impact, is inevitable during the whole life time of carbon fiber reinforced plastic (CFRP) material. However, the barely visible impact damage (BVID) is difficult to be detected by visual methods. Ultrasonic thermography (UT) is an emerging non-destructive testing technique that visualizes damage in thermal images captured by an infrared (IR) camera when the material is stimulated by ultrasound. However, noise and blurry edges around the high temperature areas may cause confusion and lead to unreliable results in the thermal images of UT test. In this work, an impact damage inspection method is proposed based on manifold learning for CFRP material. Low-power ultrasonic excitation is used for this UT. The IR image sequences are processed as data sets in high-dimensional space. These data sets are reduced to lower dimensions by manifold learning to find the intrinsic structure in the two-dimensional manifold. Each dimension of the embedding manifold correlates highly with one degree of freedom underlying the original pixel: steady and random components. The steady component, which reflects the temperature rise caused by damage, is used for VID and BVID detection. The experimental system was set up, and CFRP plate specimens with different impact damage were tested. All the impact damage could be detected and shown in reconstructed static image with little noise. The proposed method using image sequences could provide a visualized, reliable and effective impact damage inspection and localization means for CFRP material during manufacturing and in service.

The tire tread pattern affects driving significantly on icy roads, and different kinds of rubber pattern mean different friction coefficients when moving on the ice surface. Based on the latest friction test rig, a simulation method of such tests was created. Therefore, the continuous sampling at low slip velocity was proposed. During the sampling, the typical pattern of the rubber specimen was employed. The friction test of the tire tread specimen on the ice surface was implemented with different slip velocities and pressure, and the results were fitted and analyzed. To research the effect of tire tread on the friction coefficient, the rubber ratio parameter (the ratio of the rubber contact area to the total contact area) was given for proper evaluation. It is found that rubber as the major component of the tire possesses a special friction property, which is against Coulomb’s law. In addition to that, the friction coefficient of rubber is influenced by the contact state to a great extent, especially in some extreme conditions. The experiment of rubber friction on ice can serve as an important reference for the study on tire mechanical properties.

The regenerative hydraulic electric suspension (RHES) is a new type of energy regeneration damper system based on the principle of vibration energy harvesting. This system can recover the vibration energy of suspension dissipated in the form of thermal energy when vehicle travels on the road. In previous studies about RHES system, the vehicle suspension displacement is defined as varieties of periodic waves, such as sinusoidal and so on. The energy harvesting performance of damper system can be explained and evaluated to some extent, but the influence of the actual excitation condition of the road is not fully considered when studying the RHES. This paper builds models of road profiles, quarter car and power regeneration based on the proposed RHES system. Furthermore, the change laws of performance with the varies of road class, motor displacement, accumulator capacity and electrical load are summarized and the corresponding optimization suggestions are proposed, which realize the prediction and evaluation of RHES system performance under the excitation of different road profiles. Simulation suggests that this system can recover 100-400 W of power under road excitation. The findings of system analysis indicate that the component design can satisfy the damping characteristics and power performance required for specific application. The results also show that adjusting the electrical load and accumulator capacity is highly beneficial for controlling suspension behaviours, improving system reliability and increasing power regeneration.

The steering performance of off-road tires on sandy soil has a great influence on the maneuverability of the vehicle, which has long been studied by scholars. However, the discrete element method (DEM) modeling of tire steering on sand is still lacking. In this paper, an off-road tire steering model on sandy soil is established by using the discrete element method, and the parameters of the sandy soil model are calibrated based on the triaxial compression test and inclined plate experiment. Then, the parameters of the sandy soil model are verified by the reduced-scale single wheel soil bin test under a straight-driving condition. Finally, the influence of the steering radius, roll angle, roll angle, and slip rate on the tire steering process is studied. The results show that a reduction in the steering radius has a slight influence on the drawbar pull and driving torque but a greater influence on the growth of the lateral force, the aligning torque, and the reduction in sinkage. The slip rate and sideslip angle play an important role in drawbar pull, drive torque, lateral force, and torque. The roll angle has a small influence on the drawbar pull and driving torque but a greater influence on the lateral force and the aligning torque.