In metal additive manufacturing the Laser –Powder Bed Fusion (L-PBF) manufacturing process has the potential to manufacture high spec aerospace parts in an additive way rather than in a conventional subtractive way. This technology is often called revolutionary in terms of design and manufacturing potential; however it also comes with its complexity and challenges.
The quality of the printed products depends strongly on the thermal behaviour during the print process. The temperatures and the size of the melt pool can influence, among other things, print accuracy, material density, porosity, and material strength. Thermal gradients determine the thermal shrinkage and for a large part the microstructure and therefore the mechanical properties of the part. Understanding the thermal effects and conditions during the print process is needed to control and improved the process. With a controlled print process, first time right production, standardization and certification come within reach.
A Laser Powder Bed Fusion (L-PBF) printing facility is equipped with a Melt Pool Monitoring (MPM) system which monitors the laser melt pool track throughout the complete build job. From the data collected during the build and by analysing and filtering it, differences in thermal behaviour can be investigated and linked to the actual differences seen in the part.
Example of MPM data representation (left) and Ti6Al4V samples showing overheating (right)
The ultimate goal is to understand and control the thermal process in such way that methods can be developed to manage the thermal behaviour during the build job. Currently a fixed set of process parameters is used for a build job, but the printed part properties, such as microstructure, can vary throughout the part and are (strongly) depended on part geometry, laser scanning strategies and the thermal boundaries conditions.
The aim of the research is to increase understanding and to develop and improve thermal simulation model(s) to explain the thermal effects and relate those to the differences that are observed in the experiments, e.g. microstructure. This includes a literature study on focussing on the relevant parameters affecting temperature distribution and thermal gradients throughout the part. You will investigate ways to control the thermal behaviour using variable process parameters and demonstrate with a thermal simulation model. For this, different types of software can be used, Abaqus, Simufact, or a Matlab-based in-house tool. The simulations can be verified/validated with literature, MPM data or thermal camera imaging data (if feasible) from the build job. The following is a list of foreseen activities:
- Literature research; L-PBF process thermal modelling and simulation
- Develop a thermal model simulating the relevant thermal effects, verification/validation
- Demonstrate the potential of variable process parameters with the model
- Preparation of a report
- Improved model for L-PBF thermal process simulation
- Investigation on methods to validate the simulation with measurement data
- Comparison/validation of thermal model with data of actual printed test cases / benchmarks
Duration and place
The duration of this assignment is about 9 months.
The location is:
NLR Marknesse (FL)
8316 PR Marknesse, The Netherlands
Salary is 375 euro bruto
Compensation could be possible for transport or housing,
subject to restrictions
POC: Rutger Bruins, email@example.com
We are looking for a motivated student with a background in computational mechanics, preferably thermal mechanics, and experience in finite element modelling.
Study direction: Aerospace Engineering, Mechanical Engineering, Structures and Materials
Datum : 01/01/2020
Locatie : Marknesse
Uren : 40
Opleidingsniveau : MSc of BSc
Werkniveau : HBO/WO