A Fast Calculation Method of Thermal Stress in slm

Abstract

A fast calculation method for SLM thermal stress. The first step is to establish a single-pass cladding model and perform numerical simulation on the SLM forming process; the second step is to obtain the temperature field when the material reaches a quasi-stable state based on the numerical simulation of the first step ; The third step is to establish the heat transfer analysis model of the SLM formed parts and the substrate; the fourth step is to obtain the effect of multi-pass cladding on the material in the actual processing process according to the geometric characteristics and scanning strategy of the heat transfer analysis model in the third step. Influence, the fifth step is to conduct heat transfer analysis to obtain the temperature field results; the sixth step is to convert the heat transfer analysis model into a mechanical model, set constraint boundary conditions, and use the temperature field results obtained from heat transfer analysis as boundary conditions Thermal sequential coupling simulation analysis, to obtain simulation results; the seventh step, based on the thermal coupling simulation results obtained in the sixth step, to obtain the evolution process of temperature and thermal stress in the SLM process, and quantitatively analyze residual stress and deformation defects.

Description

technical field [0001] The invention relates to the field of numerical simulation, in particular to the numerical simulation of thermal stress of SLM, specifically a method for fast calculation of thermal stress of SLM. Background technique [0002] SLM (selected laser melting) technology is a representative technology of additive manufacturing. Its principle is: use the computer 3D design software to generate the 3D CAD model of the part and slice and layer it to obtain a series of 2D cross-sectional information, and then according to The cross-sectional shape data sets the heat source scanning strategy and process parameters. The scraper spreads a thin layer (about 30um in thickness) of powder on the substrate, and then the computer controls the laser heat source to selectively melt the layer of powder according to a preset path to form a two-dimensional cross-section of the part on the layer, and then the substrate descends Continue the above steps for one powder layer t...

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Problems solved by technology

The published "Empirical methodology to determine inherent strains in additive manufacturing" document (Computers and mathematics with Applications, 2018.05) mentioned that the efficiency of the inherent strain method has been significantly improved, but the temperature field information cannot be obtained and the accuracy cannot be guaranteed.

The equivalent heat source method mentioned in the published "A multiscale modeling approach forfast prediction of part distortion in selective laser melting" document (Journal of Materials Processing Technology, 2015.10) has poor accuracy and cannot reflect the actual temperature history experienced on the formed part

The "temperature function method" mentioned in the published "Efficient Algorithm Using Temperature as Control Variable in Welding Numerical Simulation" (Journal of Welding Society, 2009.08) also cannot obtain the temperature field of the formed part, and is only applicable to simple structures

The published "A survey of finite element analysis of temperature and thermal stress fields" document (Additive Manufacturing, 2018.03) mentioned that the adaptive grid method has high accuracy and efficiency, but the algorithm is complicated, and ordinary users can only purchase additional special modules. need to bear high costs

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