Preload-Induced Switchable Adhesion.

Animals with robust attachment abilities commonly exhibit stable attachment and convenient detachment. However, achieving an efficient attachment-detachment function in bioinspired adhesives is challenging owing to the complexity and delay of actuators. In this study, a class of multilayer adhesives (MAs) comprising backing, middle, and bottom layers is proposed to realize rapid switching by only adjusting the preload. At low preload, the MAs maintain intimate contact with the substrate. By contrast, a sufficiently large preload results in significant deformation of the middle layer, causing underside buckling and reducing adhesion. By optimizing the structural parameters of the MAs, a high switching ratio (up to 136×) can be achieved under different preloads. Furthermore, the design of the MAs incorporates a film-terminated structure, which prevents the embedding of dirt particles, simplifies cleaning, and maintains the separation and uprightness of the microstructures. Consequently, the MAs demonstrate practical potential for simple and efficient transportation applications, as they achieve switchable adhesion through their structure, exhibiting a high switching ratio and fast switching.

[Study on infrared characteristics of bolt and rock in condition of loading].

The infrared radiation experiments on bolt and rock in the process of loading were carried out. It was found that the infrared radiation temperatures rose wholly and uniformly before stress peak with increase in loading. The bolted rock presented local dissimilation in the thermal image after stress peak. The multi-layer round infrared radiation isothermal lines were formed around bolt. The temperature was gradually reduced from inside to outside. There were two kinds of infrared omens for bolted rock fracturing, i. e., the infrared thermal image anomaly and curve of infrared radiation temperature and time anomaly, which reflected the spatial and temporal features of infrared omens respectively. The curve of infrared radiation temperature and time anomaly was temperature drop. The infrared thermal image omen was classified as high-temperature strip and low-temperature strip.