CHAPTER 8 CONCLUSION
8.2 Recommendations
From this study recommendations for future work with regards to both the ISM and RS determination were noticed, namely:
• Usage of diffractive strain measurements to experimentally calibrate spatially varying inherent strains.
• The efficacy of ISMs in RS prediction in the presence of geometric stress raisers.
• The ability of the ISM to predict RS of complex geometries.
• The use of an orthotropic thermomechanical ISM approach in RS prediction.
• The effect of perimeter scans on the accuracy of inherent strains derived through cantilever geometries.
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APPENDIX A
Simulation parameter inputs
Appendix A represent the specification of build parameters, thermal properties, mechanical properties and simulation inputs for the ISM simulations. Mechanical properties of the materials, voxel sizes and cutting height remain unchanged between the mechanical and thermo- mechanical ISM simulations. The thermal properties shown herein represent the values used between all thermo-mechanical simulations with the exception of the volumetric expansion factor which is correlated to the HR of a specific instance.
Figure A-1: Build parameters for thermo-mechanical ISM simulations for 67° HR.
Figure A-2: Specification of directional cutting for removal of component from the build plate.
Figure A-3: Specification of thermal parameters used in thermal and thermo-mechanical ISM simulations.
Figure A -4: Initial material, chamber and base plate temperatures use in thermal and thermo-mechanical ISM simulations.
Figure A -5: Specification of build plate dimensions and material for ISM simulations.
Figure A -6: Mechanical properties of build plate used in ISM simulations.
Figure A -7: Elastic modulus of build plate varying with temperature.
Figure A -8: Thermal properties of build plate for ISM simulations.
Figure A -9: Thermal conductivity of build plate as varying with temperature.
Figure A -10: Thermal properties of IN718 powder used in ISM simulations.
Figure A -11: Thermal conductivity of IN718 powder as varying with temperature.
Table A -1: Mechanical properties of IN718 used in simulations, as varying with temperature.
Temperature Modulus of Elasticity [GPa]
20 190
200 180
400 164
800 134
1000 118
1100 110
1200 98
1500 1
1
APPENDIX B
The results presented herein represent the RS as derived from the ISM simulations on the central plane at Y = 7.5 mm.
Figure B -1: σxx simulation results.
Figure B -2: σyy simulation results.
Figure B -3: σzz simulation results.
APPENDIX C
The results of the lattice spacing as measured using ND are presented in this section in graphical format.
Figure C -1: Neutron diffraction lattice spacing.
⊥Y Z
⊥X Z
⊥X Y
0°67°90°
0 1 5
7.
5 1 2
3
Z [mm]
0 1 5
7.
5 1 2
3
Z [mm]
0 1 5
7.
5 1 2
3
Z [mm]
1 5
0 7.
5
3 1
X 2 [mm]
1 5
0 7.
5
3 1
X 2 [mm]
1 5
0 7.
5
3 1
X 2 [mm]
d-spacing [Å]
APPENDIX D
This section presents the results of the stress differences between the ND results and the simulated RS values.
Figure D -1: Central grid stress differences for 0° HR.
Figure D -2: Central grid stress differences for 67° HR.
Figure D -3: Central grid stress differences for 90° HR.
Figure D -4: Central grid σxx stress differences by height for 0° HR.
Figure D -5: Central grid σyy stress differences by height for 0° HR.
Figure D -6: Central grid σzz stress differences by height for 0° HR.
Figure D -7: Central grid σxx stress differences by height for 67° HR.
Figure D -8: Central grid σyy stress differences by height for 67° HR.
Figure D -9: Central grid σzz stress differences by height for 67° HR.
Figure D -10: Central grid σxx stress differences by height for 90° HR.
Figure D -11: Central grid σyy stress differences by height for 90° HR.