The vacuum chuck is widely used in industrial and daily life. By observing the macroscopic and microscopic morphology of octopus sucker, it is found that the sucker surface has concave–convex continuous wave shape with large number of non-smooth morphologies. The sealing mechanism of octopus sucker is analyzed according to its surface morphology before and after adsorption, and the non-smooth morphology is found to greatly enhance the adsorption. Based on the bionics theory, the non-smooth surface morphology of octopus sucker is applied to improve the sucker adsorption. And the bionic suckers with three types of grooves are designed. According to the model of standard and bionic suckers, the sucker entities are obtained by the method of three-dimensional printing and casting. And the tensile tests of suckers are carried out. The stress of suckers is analyzed by finite element method, and the sealing mechanism is discussed. According to the test results, the bionic sucker has larger adsorption force. And the ring sucker possesses the best adsorption performance. Compared with the standard sucker, the maximum adsorption force of the bionic sucker is increased by 12.2% in the air and 25.2% underwater. The adsorption force of bionic sucker becomes larger with the increase in the groove number; when the groove number increases to a certain extent, the adsorption force becomes smaller. The deformation of non-smooth morphology during adsorption makes the bionic sucker have a larger contact area. That is the reason why the bionic sucker has good adsorption performance. The bionic design of sucker can provide a new method to improve its adsorption.

This paper uses some type engine as the research object. Inspired by soil animal earthworms of the biological world and friction reduction movement of groove shape, we process grooves in the engine piston skirt's surface. Based on the standard piston's stress distribution, this paper has made nine test plans with the orthogonal experiment method. The boundary conditions of load are theoretically calculated, which apply to finite-element analysis. Then obtained three indexes, they are maximum distortion, maximum stress and maximum load of piston skirt. Comprehensive balance analysis is used in test indexes of optimization design. Finally primary and secondary factors are got, that rank is hole and groove distribution pattern (A) groove depth(B) groove wide(C) .Optimal level is A2B3C1.

Adhesion is the basic ability of many kinds of animals in nature, which ensures the survival and reproduction of animal populations. The aquatic abalone has a strong adhesion capacity. In this study, we observed the microscopic morphology of abalone abdominal foot surface, and found that the surface was covered with a large number of fibers. Then five types of force measuring plates were designed and processed for the adhesion test of abalone abdominal foot. According to the test results, the composition of abalone abdominal foot adhesion force was analyzed and the proportion of various adhesion force to the total adhesion force of abalone abdominal foot was calculated. Among them, the vacuum adhesion force accounts for more than half of the total adhesion force of abalone abdominal foot, and its proportion is more than 60%. Van der Waals force also plays an important role, and its proportion is more than 20%. The proportion of capillary force is very small, which is only about 1%. Its main role is to form a liquid film to prevent the gas from flowing into the sucker. The vacuum adhesion of abalone abdominal foot can be further divided into the whole adhesion of abdominal foot, the local adhesion of abdominal foot and the frictional equivalent vacuum adhesion. And the whole adhesion of abdominal foot is basically equivalent to the local adhesion of abdominal foot. This study quantifies the proportion of various adhesion forces to the total adhesion force of the abdominal foot, which provides a reference for the further study of other adhesive creatures and the design of bionic underwater adhesion devices.

The abalone, a marine mollusk, inhabits fast-flowing rocky reefs. Its predation and crawling abilities strongly depend on the adhesion capacity of its abdominal foot. Here, the macroscopic and microscopic morphology of the abalone foot was observed. The foot is divided into four main regions, each having a large number of folds on the surface. The extensional ability of the folds is the source of the abalone’s locomotory power. A high-speed camera was used to photograph the movement of an abalone. It was found that two to three deep-yellow round fold areas appear and disappear periodically on the surface of the foot. The folds move forward with the movement of the abalone. This results in a crawling motion that ensures efficiency of movement and adaptability of the wide abdominal foot to adsorptive surfaces. According to underwater tensile testing of an abalone, the adhesion force of the foot is composed of suction force, capillary force, friction and an interlocking structure. Among them, suction force is the most important component of the adhesion force, and the other factors play an auxiliary and reinforcing role. The strong adhesivity and adhesion-based crawling motion of the abalone may inspire new design ideas and mechanisms for underwater suckers.