Chinese Journal of Lasers, Volume. 49, Issue 14, 1402207(2022)
Effect Prediction of Stress and Deformation for Laser Additive Manufacturing of Characteristic Structure Based on Inherent Strain Method
Figures & Tables(25)
Fig. 1. Model and scanning strategy. (a) Meshing; (b) scanning without interlayer rotation
Fig. 2. Distributions of temperature field and stress field during printing of first layer. (a) Temperature field; (b) stress field
Fig. 5. Residual stress of thin-walled structure using two methods. (a) Inherent strain method; (b) thermal-elastic-plastic model
Fig. 6. 3D models and mesh generations of typical characteristic structures. (a) Crossed thin wall; (b) unsupported cantilever beam (short); (c) unsupported cantilever beam (long); (d) supported cantilever beam; (e) suspended circular hole
Fig. 7. Scanning strategies of crossed thin wall. (a) 0° line scanning; (b) 45° line scanning; (c) thickness directional line scanning; (d) 90° rotation scanning
Fig. 8. x-directional deformations of crossed thin-walled structure under four scanning strategies. (a) 0° line scanning; (b) 45° line scanning; (c) thickness directional line scanning; (d) 90° rotation scanning
Fig. 9. y-directional deformations of crossed thin-walled structure under four scanning strategies. (a) 0° line scanning; (b) 45° line scanning; (c) thickness directional line scanning; (d) 90° rotation scanning
Fig. 10. Deformations of crossed thin-walled structures with different printing heights. x-directional deformation: (a) 10 mm, (b) 20 mm, (c) 40 mm; y-directional deformation: (d) 10 mm, (e) 20 mm, (f) 40 mm
Fig. 11. Deformation of edge side of crossed thin-walled structure for different scanning strategies. (a) x-directional deformation; (b) y-directional deformation
Fig. 12. Deformations of five different height points on edge side of crossed thin-walled structure for 0° line scanning. (a) x-directional deformation; (b) y-directional deformation
Fig. 13. Deformations of unsupported cantilever beams with different lengths. (a) 60 mm; (b) 30 mm
Fig. 14. Scanning strategies of supported cantilever beam. (a) 0° line scanning; (b) 45° line scanning; (c) 90° line scanning; (d) 90° rotation scanning
Fig. 15. Deformation of supported cantilever beam after cutting under four scanning strategies. (a) 0° line scanning; (b) 45° line scanning; (c) 90° line scanning; (d) 90° rotation scanning
Fig. 16. Length directional deformations of cantilever beams under different scanning strategies
Fig. 17. Scanning strategies of suspended circular hole. (a) 0° line scanning; (b) 45° line scanning; (c) 90° line scanning; (d) 90° rotation scanning
Fig. 18. Deformation of suspended circular hole after cutting under four scanning strategies. (a) 0° line scanning; (b) 45° line scanning; (c) 90° line scanning; (d) 90° rotation scanning
Fig. 19. Residual stresses of suspended circular holes with different printing heights. (a) Residual stress along x direction; (b) residual stress along y direction; (c) residual stress along z direction
Fig. 20. Residual stress of suspension circular hole before and after cutting. (a) Residual stress along x direction; (b) residual stress along y direction; (c) residual stress along z direction
Table 1. Process parameters used for LPBF of Ti-6Al-4V
View tableTable 1. Process parameters used for LPBF of Ti-6Al-4V
Process parameter Value Laser power /W 150 Laser scan speed /(m·s－1) 1.2 Radius of laser spot /μm 50 Emissivity 0.3 Hatch spacing /μm 100 Optical penetration depth /μm 65
Table 2. Thermo-physical parameter of Ti-6Al-4V[30]
View tableTable 2. Thermo-physical parameter of Ti-6Al-4V[30]
Thermo-physical parameter Content Solidus temperature /K 1878 Liquidus temperature /K 1928 Thermal conductivity [W/(m·K)] 1.57＋1.6×10－2T－7×10－6T2 @273-2273 K Specific heat [J/(kg·K)] 512.4＋0.15T－1×10－6T2 @273-2273 K Density /(kg·m－3) 4000
Table 3. Mechanical properties of Ti-6Al-4V[6]
View tableTable 3. Mechanical properties of Ti-6Al-4V[6]
Temperature /K Young’s modulus /(109 Pa) Poisson’s ratio Thermal expansion coefficient /(10－5 K－1) Temperature /K Yield stress /(108 Pa) 300 1.25×102 0.345 8.76×10－1 300 9.55 533 1.10×102 0.35 9.83×10－1 573 8.36 589 1.00×102 0.37 1.00 773 7.32 700 9.30×10 0.43 1.07 1023 5.81 755 8.00×10 0.43 1.11 1073 5.47 811 7.40×10 0.43 1.12 1173 4.8 923 5.50×10 0.43 1.17 1273 4.05 1073 2.70×10 0.43 1.22 1373 3.3 1098 2.20×10 0.43 1.23 - - 1123 1.80×10 0.43 1.24 - - 1573 1.20×10 0.43 1.30 - - 1873 9.00 0.43 1.63 - -
Table 4. Dimensional sizes of typical characteristic structures
View tableTable 4. Dimensional sizes of typical characteristic structures
Typical characteristic structure Dimensional size Crossed thin wall L＝60 mm，W＝60 mm，H＝40 mm，δ2＝10 mm Unsupported cantilever beam (short) L＝30 mm，W＝7.5 mm，H＝16 mm，δ1＝5 mm Unsupported cantilever beam (long) L＝60 mm，W＝7.5 mm，H＝16 mm，δ1＝5 mm Supported cantilever beam L＝60 mm，W＝10 mm，H＝16 mm，δ1＝5 mm Suspended circular hole L＝20 mm，W＝10 mm，H＝8 mm，φ＝4 mm
Table 5. Mesh sizes, numbers of elements and equivalent layer thicknesses of typical characteristic structures
View tableTable 5. Mesh sizes, numbers of elements and equivalent layer thicknesses of typical characteristic structures
Typical characteristic structure Mesh size /mm Number of elements Equivalent layer thickness /mm Crossed thin wall 1 44000 1 Unsupported cantilever beam (short) 0.5 16920 0.5 Unsupported cantilever beam (long) 0.5 25920 0.5 Supported cantilever beam 0.5 55680 0.5 Suspended circular hole 0.25 96600 0.25
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Qingyuan Yin, Huiliang Wei, Changchun Zhang, Tingting Liu, Wenhe Liao. Effect Prediction of Stress and Deformation for Laser Additive Manufacturing of Characteristic Structure Based on Inherent Strain Method[J]. Chinese Journal of Lasers, 2022, 49(14): 1402207
Paper Information
Received: Jan. 10, 2022
Accepted: Mar. 7, 2022
Published Online: Jun. 14, 2022
The Author Email: Wei Huiliang (hlwei@njust.edu.cn)
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