How to – Model the Additive Manufacturing Process


Over the last decade the Additive Manufacturing process has attracted a high level of interest due to the potential that the process has to revolutionise the way engineering companies design products. As well as offering rapid cycle times from initial concept to finished product it also allows previously unmanufacturable designs to be produced. However, even with AM, it is not possible to just “print” any shape out of metal. Distortion and cracking are recurring issues. Process simulation has a key role to play in resolving these issues and optimising the process parameters.

This document provides guidance for people wanting to predict residual stress and distortion of metal additive manufactured parts using a physics-based numerical simulation of the manufacturing process.

It is relevant for processes in which metal is cooled down from a molten state or a very high temperature, such as Powder Bed Fusion and Directed Energy Deposition. Although much has already been written about this family of processes and their simulation, this text contains some pragmatic guidance needed to obtain good results for everyday industrial use. For example, what to pay attention to when selecting a simulation software if you need to predict build stressinduced part buckling? What time-step to impose on a simulation intended to accurately predict cooling rates?

Contents

1Why simulate? 1
2How to simulate? 3
3.1Thermo-mechanical simulation 3
2.2Inherent strain based simulation 3
3Thermo-mechanical simulation method 5
3.1Heat-source model 5
3.2Spatial discretisation and aggregation of layers 7
3.3Element activation or birth and temporal discretisation 9
3.4Risk of inducing errors / factors that most strongly influence precision 12
3.5Model set up time 21
3.6Simulation time 22
3.7Outputs and words of warning 24
4Inherent strain simulation method 27
4.1Variants of the inherent strain approach 27
4.2Spatial discretisation and layer aggregation 28
4.3Temporal discretisation for inherent strain simulation 30
4.4Inherent strain identification 31
4.5Material properties for inherent strain analyses 33
4.6Risk of inducing errors / opportunity of improving accuracy 33
4.7Risk of missing certain failure modes and counter-distortion 33
4.8Model set up time 34
4.9Simulation time 35
4.1Outputs and words of warning 36
5References 37
6Acronyms 43

 

Document Details

Reference

HT53

Authors

Van-Der-Veen. S;Hurrell. P;London. T;Megahed. M;Rome J;Saunders. B

Language

English

Type

Publication

Date

2022-02-21

Organisations

Region

Global

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