표제지
초록
Abstract
목차
제1장 서론 12
1.1. 연구 배경 12
제2장 LPBF 공정변수에 따른 영향 분석 14
2.1. 금속 적층 가공 기법 14
2.2. 시편 준비 15
2.3. LPBF 공정변수 설정 18
2.4. 상대밀도 및 표면 거칠기 측정 21
2.4.1. 상대밀도 측정 21
2.4.2. 표면 거칠기 측정 23
2.5. 실험 결과 24
제3장 격자구조물의 구조해석 기법 32
3.1. 격자구조물 형상설계 및 제작 32
3.2. 균질화 기법을 이용한 유효물성 예측 34
3.2.1. 유효 물성치 계산 34
3.2.2. mesh 수렴도 해석 37
3.2.3. 유효 물성 계산 검증 39
3.3. 압축 시험 및 해석 데이터 분석 40
제4장 결론 및 향후 계획 43
제5장 참고 문헌 45
제6장 부록 47
Table 1. Processing parameters used in laser powder bed fusion for optimization 20
Table 2. Process parameters for lattice structure printing 33
Table 3. Ti-6Al-4V mechanical properties data 41
Figure 1. The examples including AM lattice structure usage: (a) Cellcore's prototype rocket nozzle and (b) Thales Alenia Space's satellite solar panel 13
Figure 2. Representative scheme of the LPBF and DED additive manufacturing 14
Figure 3. (a) Size distribution of particles of Ti-6Al-4V, (b) SEM image of powder particles 16
Figure 4. SLM 125 HL Machine 17
Figure 5. Ti-6Al-4V cube set printed with various processing parameters 18
Figure 6. Illustration of parameters for LPBF processing 19
Figure 7. Angle rotation increment between consecutive layers 20
Figure 8. Measurement by Archimedes method 21
Figure 9. Image analysis of optical image with 'Image J' 22
Figure 10. Optical image and converted image for surface roughness 23
Figure 11. Hatching space change: optical image and relative density 25
Figure 12. Hatching space change: converted image and RMS roughness 26
Figure 13. Laser power change: optical image and relative density 27
Figure 14. Laser power change: converted image and RMS roughness 28
Figure 15. Optical images the 75 W (up) and 375 W (bottom) 29
Figure 16. Laser angle rotation change: optical image and relative density 30
Figure 17. Laser angle rotation: converted image and RMS roughness 31
Figure 18. Lattice structure unit cells 33
Figure 19. LPBF-fabricated octet lattices 34
Figure 20. RVE of octet structure 34
Figure 21. Coordinate system used in homogenization method 35
Figure 22. Periodic boundary condition 35
Figure 23. Schematic of displacement boundary conditions applied to calculate the effective elastic properties 37
Figure 24. Mesh sensitivity of Octet unit cell (4 x 4 x 4) mm 38
Figure 25. Full-FEA simulation for (a)lattice structure and (b)equivalent solid 38
Figure 26. Compression boundary conditions for validation of effective properties 39
Figure 27. compression analysis (a) octet lattice structure , (b)equivalent model 40
Figure 28. Boundary condition for compression test 41
Figure 29. Comparison of the FEA simulation of octet lattice structure, experiment test and equivalent model 42