Abstract
The surface morphology of parts has an important influence on service performance, such as wear resistance, fatigue resistance, and corrosion resistance. For example, the fatigue fracture resistance of the surface of the automobile cover mold directly determines the quality of the workpiece and the service life of the mold. In nature, the pit-shaped non-smooth form of the surface of certain organisms has good fatigue resistance. Using laser processing and other methods to prepare a pit-shaped bionic non-smooth surface on the surface of the part is an effective method to improve the fatigue resistance of the mold surface. Ball-end milling can form a regularly distributed pit-like surface morphology, and has the advantages of high processing efficiency, wide operating range, and low production cost compared with those of laser processing and preparation technology. It provides a new processing method for efficient milling preparation of bionic surfaces. In this paper, the morphology of the quadrilateral pits on the surface of the dung beetle is used as the prototype of the bionic design, and the mechanism of the antifatigue crack propagation characteristics of the quadrilateral pits of the bionic dung beetle is revealed and analyzed. The fatigue crack growth has a good retarding effect. At the same time, through numerical simulation and experimental research on the fatigue crack growth characteristics of the surface of the bionic pit, the results show that the source of fatigue cracks often starts inside the surface of the processed bionic pit, and the surface of the quadrilateral pit on the surface of the bionic dung beetle has good antifatigue crack growth characteristics.
Highlights
The processed surface formed by the high-speed milling of the hardened steel mold reflects the surface state of its final use, and the processed surface state directly affects the service life of the mold [1]
The comparative test results show that the surface morphology of the quadrilateral bionic pits has good accuracy in the analysis of the mechanism of inhibiting fatigue crack growth
Based on the previous analysis results, the bionic quadrilateral pits on the surface of the dung beetle have better characteristics for retarding fatigue crack growth, which means that the bionic morphology has better fatigue resistance
Summary
The linear elastic fracture mechanics method became the most commonly used method for fatigue crack growth analysis. In the linear elastic fracture mechanics theory, the stress intensity factor K is commonly used to characterize the strength of the crack tip stress field, and its value depends on the size of the load, the shape of the crack, etc., [23]. In 1963, Paris et al [24] first proposed to associate the fatigue crack growth rate with the stress intensity factor ∆K. The Paris formula widely used in engineering is used to describe the fatigue crack growth characteristics of the bionic specimen, and its expression. In the formula, f represents the structural geometry and crack size coefficient, and. ∆K represents the stress amplitude at the crack
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