Xu Song
Xu Song PhD
Singapore Institute of Manufacturing Technology (SIMTech)
Singapore
Email: xu.song@simtech.a-star.edu.sg
Abstract:
Advances in AM Process Simulation: Residual Stress Predictions for Laser Direct Energy Deposited Thin Wall Components and Overhanging Structures Manufac-tured via Selective Laser Melting
Due to solidification of melted powders in additive manufacturing processes, large residual stresses are created in the build. This can lead to unwanted distortions during the building phase, as well as crack initiation, propagation and immature failure. The main aim of this work is to optimize the additive manufacturing process parameters by finite element modeling and to simulate the resulting residual stresses and distortions. We focus on two manufacturing processes: (a) Laser Direct Energy Deposition (LDED), which is a powder-blown AM technology and (b) Selective Laser Melting (SLM), which is a powder-bed AM technology. The modelling results are validated through microstructure studies, residual stress measurements and distortion measure-ments. We employ the latest ABAQUS AM module to simulate both processes, as it provides new interface allowing the user to define floating point data as a function of position and time to achieve a fully-automated two-step 3D printing process simula-tion. Heat transfer and stress analysis are performed sequentially. For LDED processes, thin wall components are simulated and the residual stresses are predicted and com-pared with both FIB-DIC and XRD residual stress measurement results at different scales. It is shown that by using the optimal processing parameters for laser cladding, tensile residual stresses are still generated, with a high value, at the starting and ending positions of the wall, and especially at the corners. Cracks at the corners are also ob-served during sample preparation. For the SLM process, overhanging structures with different support thicknesses are simulated. The influence of laser path time series de-scription, time increment and surrounding powder-bed material on the resulting stress-es and distortions was evaluated. We show that the support thickness plays a key role in controlling residual stresses and resulting distortions, which is also supported by experimental measurements.
Singapore Institute of Manufacturing Technology (SIMTech)
Singapore
Email: xu.song@simtech.a-star.edu.sg
Abstract:
Advances in AM Process Simulation: Residual Stress Predictions for Laser Direct Energy Deposited Thin Wall Components and Overhanging Structures Manufac-tured via Selective Laser Melting
Due to solidification of melted powders in additive manufacturing processes, large residual stresses are created in the build. This can lead to unwanted distortions during the building phase, as well as crack initiation, propagation and immature failure. The main aim of this work is to optimize the additive manufacturing process parameters by finite element modeling and to simulate the resulting residual stresses and distortions. We focus on two manufacturing processes: (a) Laser Direct Energy Deposition (LDED), which is a powder-blown AM technology and (b) Selective Laser Melting (SLM), which is a powder-bed AM technology. The modelling results are validated through microstructure studies, residual stress measurements and distortion measure-ments. We employ the latest ABAQUS AM module to simulate both processes, as it provides new interface allowing the user to define floating point data as a function of position and time to achieve a fully-automated two-step 3D printing process simula-tion. Heat transfer and stress analysis are performed sequentially. For LDED processes, thin wall components are simulated and the residual stresses are predicted and com-pared with both FIB-DIC and XRD residual stress measurement results at different scales. It is shown that by using the optimal processing parameters for laser cladding, tensile residual stresses are still generated, with a high value, at the starting and ending positions of the wall, and especially at the corners. Cracks at the corners are also ob-served during sample preparation. For the SLM process, overhanging structures with different support thicknesses are simulated. The influence of laser path time series de-scription, time increment and surrounding powder-bed material on the resulting stress-es and distortions was evaluated. We show that the support thickness plays a key role in controlling residual stresses and resulting distortions, which is also supported by experimental measurements.