No abstract

Process evaluation is widely accepted as an effective strategy to improve product quality and shorten its development cycle. However, there has been very little research on how to evaluate the process plan with the dynamic change of the machining condition and uncertain available manufacturing resources. This paper proposes a novel process evaluation method based on digital twin technology. Three core technologies embodied in the proposed method are illustrated in details: 1) real-time mapping mechanism between the collected data in machining and the process design information; 2) construction of the digital twin-based machining process evaluation (DT-MPPE) framework; and 3) process evaluation driven by digital twin data. To elaborate on how to apply the proposed method to the reality, we present a detailed implementation process of the proposed DT-MPPE method for the key parts of the marine diesel engine. Meanwhile, the future work to completely fulfill digital twin-based smart process planning for complex products is discussed. INDEX TERMS Digital twin, process planning, process evaluation, mapping mechanism, digital twin data.

In the past decades, drag-reduction surfaces have attracted more and more attention due to their potentiality and wide applications in various fields such as traffic, energy transportation, agriculture, textile industry, and military.

Puffers show good drag reduction performance during migration. It is worth noting that spines which are different from ordinary fish scales are densely distributed on the puffer skin. Here, the special morphological structure of puffer spines was observed using microscopy techniques, accurate contour models were established based on image processing techniques and curve fitting, then feature sizes were obtained. Based on the results, the nonsmooth surface was established by orthogonal test to simulate the flow field. In addition, the influence of spinal structure on boundary layer flow field and the drag reduction property of nonsmooth surface were further analyzed. The nonsmooth surface formed by spinal structure elements can effectively reduce the wall shear stress and Reynolds stress, and there was a special “climbing vortex” phenomenon, so as to reduce the surface viscous friction resistance and achieve drag reduction. Compared with the smooth surface, the drag reduction rate of the nonsmooth surface was 12.94% when the inflow velocity was 5 m/s, which revealed and verified the drag reduction performance of the spines of puffer skin. The results lay a foundation for further research and optimization of drag reduction ability of nonsmooth surface of bionic spines.Highlights The contour of the spinous process was accurately reflected by the Fourier function. The spines of puffer skin have good drag reduction effect. There was a special “climbing vortex” phenomenon to explain the drag reduction property.