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The aim of this work was to investigate the impact of nanosecond pulse laser drilling on the quality of carbon fiber reinforced polymer (CFRP). The effects of laser parameters, including laser power, scan speed, pulse width and laser frequency on micro-hole quality and the thermal damage generated during the drilling process were analyzed. 0.4 mm diameter micro-holes were drilling using a 1064 nm fiber laser, using univariate and orthogonal experimental method. The results indicate that pumping at the entrance leads to a significant increase in hole diameter and heat-affected zone (HAZ) width at both the entrance and exit, as laser power, pulse width and frequency increase, and scanning speed decrease. The width of the HAZ at the exit is dependent on whether the energy reaches the carbon fiber ablation threshold. The holes were tapered and the hole taper was closely related to the change in laser parameters at the entrance and exit of the hole. A taper of approximately 0.3 was achieved with a combination of 99 W, 50 mm/s, 13 ns and 1500 kHz. The experiments indicate that laser power and pulse width are crucial factors that affect the quality of micro-hole processing. However, nanosecond laser drilling can result in thermal damage defects, including striations, micro-cracks, delamination, voids and surface fiber 'fish scale' peeling. [ABSTRACT FROM AUTHOR]

The increase in port scale and business complexity has led to an increased demand for comprehensive and lean control on ports. The current operation mode is facing the bottleneck of the increasingly significant production efficiency and performance. Digital twin (DT) technology realizes holographic visual management and control patterns using cyber-physical fusion and promotes the transformation of a port to an intelligent operation mode. In this paper, the framework of a digital twin application system is proposed based on the analysis of business characteristics of large-scale comprehensive ports. Construction methods and technologies such as digital twin modeling, global ubiquitous perception, data mapping, and model fusion are analyzed. With regard to the construction needs of Qingdao Port's digital twin system, this paper presents a case study and illustrates the overall design process and function of the digital twin system for typical terminals. The system realizes the intelligent operation of the port with the core functions of three-dimensional visual monitoring and optimal dispatching based on real-time perception data. This paper serves as a feasible reference for future intelligent development of large ports and the application of digital twin technology. [ABSTRACT FROM AUTHOR]

Soft abrasive flow (SAF) finishing has advantages in precise processing for titaniferous alloy parts with large-area surfaces. However, the processing efficiency and surface quality of current SAF methods require to be improved. To address the issues, a novel gas–liquid-solid three-phase rotary abrasive flow polishing method (RGLSP) is proposed based on the microbubble cavitation effect. Referring to the energy conservation principles of bubbles group movement, an improved realizable k-ε turbulence model is set up. Based on the above model, a mechanical dynamic model of the machining apparatus is established to obtain the flow field distribution of different structural parameters. The simulated results show that the pitch-down angle determines the distribution of the rotary flow field, and an optimized processing apparatus is developed. The machining experiments show that the proposed RGLSP method can improve the machining efficiency by 60%, and the surface roughness can reach Ra 0.1 μm with lower surface defects. The RGLSP can provide an important reference direction for low-carbon emission processing. [ABSTRACT FROM AUTHOR]