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[Display omitted] • In this paper, the mechanical and friction experiments of composite hydrogels used in biomedical field in recent 3 years are summarized. • In this paper, the shortcomings of mechanical and friction experiments of biological hydrogels in recent 3 years were evaluated. • A more comprehensive method for testing the properties of biological hydrogels is put forward in this paper. Hydrogel is a porous three-dimensional network material that is insoluble in water and can store a large amount of water. This material has excellent mechanical properties, such as medical fields, wastewater treatment and other fields, and are widely used. With the development of modern science and technology, the research on hydrogel, a new kind of biomaterial, is increasingly extensive. Many researchers have carried out research on bone tissue-related engineering based on the advantages of hydrogel, such as adjustable mechanical properties, convenient production and combination with bioactive factors. The researchers mainly focus on the mechanical properties and biocompatibility of hydrogel made of composite materials. The disease causes extensive trauma, broken bones and cartilage damage that does not heal on its own, while traditional surgical treatments can bring side effects such as infection, inflammation and pain. As a new kind of biomaterial, hydrogel has controllable mechanical properties and biocompatibility, and is widely used in bone tissue engineering as scaffold material for growth factor transport and cell adhesion. In order to make hydrogels more suitable for local treatment of orthopedic diseases, the excellent properties of hydrogels are combined with synthetic materials with advanced technologies in different fields. In this paper, the test methods used in the study of mechanical and tribological properties of bone repair hydrogels are reviewed, and the shortcomings of experimental methods in the study of cartilage repair hydrogels are pointed out. the application of the combination of mechanics and tribology in the study of cartilage repair and cartilage replacement was discussed, and the research progress of molecular dynamics in characterizing the micromechanical state of hydrogel was summarized. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of iron powder types and contents on the friction and wear properties of copper matrix composites for breaking of high-speed trains were investigated through microstructure observations and components analysis of tribofilm. • The wettability and combination between ferrophosphorus and matrix is poor and carbonyl iron is more suitable for strengthening matrix. The friction coefficient is most stable and the wear rate is also relatively low with 10% carbonyl iron. • The increase of carbonyl iron content can promote the formation of the friction film and improve the thickness, hardness and strength of the film. When the Fe content is larger than 10%, it accelerates the generation of the friction film. However, cracks are easy to form between the thicker film and softening matrix, which leads to large wear and fluctuating friction coefficient. • The oxide process during the braking is carried out from the surface to the matrix. The oxide degree of friction film increases in the direction from the matrix to the surface. This paper studied the effects of iron powder types and contents on the friction and wear properties of copper matrix composites for breaking of high-speed trains. The mechanical properties, microstructure, interface, tribofilm, elements and microhardness of samples were analyzed by hardness tester, SEM, EDS and nanoindentation tests. The braking performances were measured by a tribometer mimicking the braking conditions. The results show that the wettability and combination between ferrophosphorus and matrix is poor and carbonyl iron is more suitable for strengthening matrix. The friction coefficient is most stable and the wear rate is also relatively low with 10% carbonyl iron. The increase of carbonyl iron content will promote oxidation and be conducive to the formation of friction film. The oxide degree of friction film increases in the direction from the matrix to the surface. However, too much iron powder produces excessive iron oxide which makes the friction film be easy to peel off especially under high speeds. [ABSTRACT FROM AUTHOR]