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Thermomechanical Simulation for Distortion and Residual Stress Prediction in SLM Parts: Sensitivity Analysis II
Excessive distortion and the existence of high levels of residual stress are of the major concern for AM products. The sensitivity of predicted residual stress to the type of material constitutive model will be evaluated.
Keywords: Additive Manufacturing, Thermomechanical simulation, Material model, Sensitivity analysis
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 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 the 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.
An important consideration for thermomechanical modelling is the constitutive deformation material model which describes the stress-strain (-time) relationship for the material at different temperatures. It is expected that the thermomechanical simulation results are strongly sensitive to the type of considered constitutive model formulation. However, such sensitivity has not been ever systematically investigated.
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 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 the 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.
An important consideration for thermomechanical modelling is the constitutive deformation material model which describes the stress-strain (-time) relationship for the material at different temperatures. It is expected that the thermomechanical simulation results are strongly sensitive to the type of considered constitutive model formulation. However, such sensitivity has not been ever systematically investigated.
The aim of the present student project is to investigate the sensitivity level of predicted distortion and residual stresses within an SLM part to the type of deformation constitutive model.
The observations from a comprehensive mechanical testing program will be employed to underpin different types of constitutive deformation material models, namely: a) elastic, b) elastic/ideal plastic, c) elastic/isotropic-hardening plastic, d) elastic/kinematic-hardening plastic, e) elastic-visco-plastic. The different constitutive models will be employed in ABAQUS FE package for thermomechanical simulation of a single SLM part and the sensitivity of the predicted residual stresses and distortion will be evaluated.
This project is suitable for **ETH** MSc/BSc students who have a background or interest in computational mechanics and finite element modelling. S/he will be working in close contact with our PhD student who is working on the thermomechanical simulation of the SLM process.
The aim of the present student project is to investigate the sensitivity level of predicted distortion and residual stresses within an SLM part to the type of deformation constitutive model.
The observations from a comprehensive mechanical testing program will be employed to underpin different types of constitutive deformation material models, namely: a) elastic, b) elastic/ideal plastic, c) elastic/isotropic-hardening plastic, d) elastic/kinematic-hardening plastic, e) elastic-visco-plastic. The different constitutive models will be employed in ABAQUS FE package for thermomechanical simulation of a single SLM part and the sensitivity of the predicted residual stresses and distortion will be evaluated.
This project is suitable for **ETH** MSc/BSc students who have a background or interest in computational mechanics and finite element modelling. S/he will be working in close contact with our PhD student who is working on the thermomechanical simulation of the SLM process.
Contact:
Dr. Ehsan Hosseini ehsan.hosseini@mavt.ethz.ch
Mr. Patrik Markovic patrik.markovic@empa.ch
Contact: Dr. Ehsan Hosseini ehsan.hosseini@mavt.ethz.ch Mr. Patrik Markovic patrik.markovic@empa.ch