Numerical Simulation Of Deformation Of Typical Thin-walled Parts In Laser Selective Melting Forming Based On Inherent Strain Method

The SLM technology has advantages such as no need for molds and unrestricted complexity of part shapes,and is widely used in the metal manufacturing field.However,during SLM forming,the high-energy density of the laser generates temperature gradients and residual stresses,which can lead to deformation,cracking,and even manufacturing interruption of metal parts.Thin-walled parts are particularly prone to deformation.Currently,there is limited research on the deformation patterns of thin-walled parts in SLM forming,especially the deformation patterns related to part size and shape,and how to control these deformations.This paper uses the numerical simulation method of inherent strain to study the stress and deformation distribution patterns of thin-walled plates with different lengths,heights,and thicknesses in SLM forming,and studies the deformation distribution of typical shaped thin-walled parts.A deformation control method based on reverse deformation compensation design is proposed.The main conclusions of this paper are as follows:(1)Using the BLT-A160 device of Xi’an BLT Company,a cantilever beam was printed on the X and Y axes to measure the deformation by warping experiments.After multiple measurements and taking the average,the maximum warping deformation values in the X and Y directions of the cantilever beam were found to be2.041 mm and 1.594 mm,respectively.With the calibrated inherent strain value,it is possible to accurately simulate the strain and deformation of printed parts and predict the performance and quality of parts.This is a critical step in ensuring the success of additive manufacturing processes and high-quality parts.(2)In thin-walled structures,the deformation in the X direction dominates,with the maximum deformation occurring in the center and showing a concave shape.As the height and length increase,the maximum deformation in the X direction first increases and then stabilizes,while the deformation in the center tends to be stable.In addition,as the thickness of the thin-walled structure increases,its deformation gradually decreases.(3)The variation of X-directional stress with height for thin plates with different heights,lengths,and thicknesses during rapid printing is described.The thin plate has a maximum stress value at the beginning of printing.As the height increases,the stress in the center of the thin plate stabilizes,and tensile stresses appear at the bottom and top,while compressive stress appears in the center.The thicker the thin plate,the higher the maximum stress value.Overall,the thin plates of different sizes all experience tensile stress at the bottom and top,and a stable compressive stress in the center.(4)This study employed SLM forming to create semi-circular rings and semi-square box parts.The parts underwent deformation compensation,and their three-dimensional(3D)scanning and deviation analysis were performed using Handy SCAN300 3D laser scanner and Geomagic Studio software.The results showed that prior to compensation,the parts’ sharp corners exhibited significant deformation.Following compensation,there was a 32.2% and 31.8% reduction in the average maximum positive deviation,and a 23.4% and 32.5% decrease in the average maximum negative deviation,respectively.Standard deviation declined by 32.5% and32.7%,while RMS Estimate fell by 31.7% and 31.9%.Therefore,deformation compensation technology can mitigate SLM-formed parts’ deformation to a certain extent.