Abstract During laser manufacturing, the inevitably generated thermal stress may lead to cracks and defects, thus resulting in work-piece damages. In order to optimize laser manufacturing to inhibit the stress, detailed analysis on the time-varying stress field is necessary. Compared to experimental stress measurement requiring expensive setups and complicated procedures, numerical stress calculation techniques attract much attentions because of their simple and cost-effective requirements as well as multi-parameter analysis capability. However, most of them can only numerically calculate the residual strain in steady state, ignoring the time-varying stress analysis during the laser fabrication. Besides, they did not consider the thermal softening effect with stress release, thus decreasing the accuracy in laser fabrication analysis. In order to realize real time stress analysis inside the work-piece with high accuracy, in this paper, we designed an online monitoring method composing of level set method for free surface monitoring, thermal transfer theory for temperature field calculating and thermo-elasticity theory for stress field retrieving. Proved by the comparisons between the numerical simulations and practical measurements, it is believed that the proposed model can provide quantitative stress with high precision for future stress analyze and laser manufacturing optimization.

中文翻译：

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毫秒激光器制造中热应力的演变

摘要 在激光制造过程中，不可避免地产生的热应力可能导致裂纹和缺陷，从而导致工件损坏。为了优化激光制造以抑制应力，需要对时变应力场进行详细分析。与需要昂贵设置和复杂程序的实验应力测量相比，数值应力计算技术因其简单、经济高效的要求以及多参数分析能力而备受关注。然而，他们中的大多数只能数值计算稳态残余应变，而忽略了激光器制造过程中的时变应力分析。此外，他们没有考虑应力释放的热软化效应，从而降低了激光制造分析的准确性。为了实现高精度实时工件内部应力分析，本文设计了一种由水平集法自由表面监测、热传递理论计算温度场和热弹性理论组成的在线监测方法。应力场检索。通过数值模拟和实际测量的对比证明，所提出的模型可以为未来的应力分析和激光制造优化提供高精度的定量应力。用于温度场计算的热传递理论和用于应力场反演的热弹性理论。通过数值模拟和实际测量的对比证明，所提出的模型可以为未来的应力分析和激光制造优化提供高精度的定量应力。用于温度场计算的热传递理论和用于应力场反演的热弹性理论。通过数值模拟和实际测量的对比证明，所提出的模型可以为未来的应力分析和激光制造优化提供高精度的定量应力。