Selective laser melting (SLM) is a powder-bed fusion additive manufacturing (AM) process for layer-by-layer fabrication of (complex) three-dimensional parts. During the process, a laser beam scans over a powder bed and the laser energy is directly absorbed by the powder particles. This leads to a rapid increase in the temperature and melting. As the laser beam moves away, the molten material rapidly cools down and solidifies. Rapid cooling rates and steep temperature gradients cause development of significant residual stresses in SLM parts which affect their in-service mechanical performance. Furthermore, relaxation of the developed stresses during or after the SLM process cause distortion of the built part and violation of their geometrical tolerances.
Numerical models are required to predict the distribution of residual stresses and distortion of SLM parts, and explain their relationship with SLM process parameters and part geometry. Furthermore, they can be used to find the optimal process parameters or optimize the part geometry in order to improve residual stress state and reach acceptable distortion levels.
Thermomechanical simulation of SLM is a challenging task as it involves the calculation of a highly localized transient temperature (and stress) field generated by a laser with a typical radius of 30-100 μm and a velocity of 100-1000 mm/s. Thus a well-founded numerical analysis requires fine space and time discretization on the order of micrometers and microseconds, respectively, which makes reliable large-scale thermomechanical simulations almost impossible.
Several approximate solutions have been proposed with the aim of reducing the computational cost of the simulations and allowing for large-scale modeling. Autodesk has introduced Netfabb® additive manufacturing software with proven efficiency in reducing the thermomechanical computational cost of SLM processes.
The aim of the present student project is to employ Netfabb® software for prediction of distortion and residual stress development during SLM processes. The reliability and computational effectiveness of this approach will be compared with the results generated by the ABAQUS FE package.
Candidates should have a background or interest in computational mechanics and finite element modeling.
Selective laser melting (SLM) is a powder-bed fusion additive manufacturing (AM) process for layer-by-layer fabrication of (complex) three-dimensional parts. During the process, a laser beam scans over a powder bed and the laser energy is directly absorbed by the powder particles. This leads to a rapid increase in the temperature and melting. As the laser beam moves away, the molten material rapidly cools down and solidifies. Rapid cooling rates and steep temperature gradients cause development of significant residual stresses in SLM parts which affect their in-service mechanical performance. Furthermore, relaxation of the developed stresses during or after the SLM process cause distortion of the built part and violation of their geometrical tolerances. Numerical models are required to predict the distribution of residual stresses and distortion of SLM parts, and explain their relationship with SLM process parameters and part geometry. Furthermore, they can be used to find the optimal process parameters or optimize the part geometry in order to improve residual stress state and reach acceptable distortion levels. Thermomechanical simulation of SLM is a challenging task as it involves the calculation of a highly localized transient temperature (and stress) field generated by a laser with a typical radius of 30-100 μm and a velocity of 100-1000 mm/s. Thus a well-founded numerical analysis requires fine space and time discretization on the order of micrometers and microseconds, respectively, which makes reliable large-scale thermomechanical simulations almost impossible. Several approximate solutions have been proposed with the aim of reducing the computational cost of the simulations and allowing for large-scale modeling. Autodesk has introduced Netfabb® additive manufacturing software with proven efficiency in reducing the thermomechanical computational cost of SLM processes. The aim of the present student project is to employ Netfabb® software for prediction of distortion and residual stress development during SLM processes. The reliability and computational effectiveness of this approach will be compared with the results generated by the ABAQUS FE package. Candidates should have a background or interest in computational mechanics and finite element modeling.