Research on simulation of nanosecond pulsed laser processing for TC4 titanium alloy: A novel model simplification and correction method

With the increasingly prominent issues of energy shortages and environmental protection, the research on spacecraft drag reduction has attracted widespread attention from industrialists. Surface microgrooves can effectively reduce the friction of spacecraft walls, which can be manufactured by a nanosecond laser. However, the machining process of nanosecond laser is affected by the coupling of multiple process parameters, and the processing morphology is difficult to recognize, restricting the high-precision processing of microgrooves. Therefore, accurate identification of nanosecond laser processing morphology is a prerequisite for ensuring the drag reduction performance of spacecraft. In this study, TC4 titanium alloy that is the aviation material is used as the research object, and the finite element model (FE model) for nanosecond laser processing is established. In this model, the nanosecond laser obeys the Gaussian distribution in time and space. In addition, thermal conduction, thermal convection, and thermal radiation are considered in the model. The rapid phase change of the material during laser processing is realized by using a significant convection coefficient, and finally processing profile is simulated by the deformation geometry technology. To improve the calculation efficiency of the FE model, the pulsed laser is equivalently processed, which significantly improves the computational efficiency. The prediction accuracy of the processing profile is improved, where the FE model is revised based on the experimental data. The relative error between the simulated depth and the machining depth is less than 9%. More importantly, the simulated morphology is in good agreement with the experimental data. The validity and reliability of the FE model are verified, which can guide nanosecond laser processing of microgrooves. Further, the proposed pulsed laser equivalent method and the model correction method will promote the three-dimensional simulation process of ultrafast lasers.