Implementation of a thermomechanical model for the simulation of selective laser melting

Hodge, Neil E.; Ferencz, Robert M.; Solberg, Jerome

doi:10.1007/s00466-014-1024-2

Cited by 283 publications

(186 citation statements)

References 18 publications

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“…General coupled thermo-mechanical analyses of SLM have been reported by several authors [16][17][18][19], but these did not examine in detail the effects of laser scan strategy and are mainly focused on developing modelling techniques. Observations from such simulations have included the reporting of an asymmetric melt-pool and that the largest stress component was generated parallel to the scanning direction, agreeing with previous experimental studies [14].…”

Section: Introductionmentioning

confidence: 99%

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Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Parry

Ashcroft

Wildman

2016

Additive Manufacturing

421

287

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract: Selective laser melting (SLM) is an attractive technology, enabling the manufacture of customised, complex metallic designs, with minimal wastage. However, uptake by industry is currently impeded by several technical barriers, such as the control of residual stress, which have a detrimental effect on the manufacturability and integrity of a component. Indirectly, these impose severe design restrictions and reduce the reliability of components, driving up costs. This paper uses a thermo-mechanical model to better understand the effect of laser scan strategy on the generation of residual stress in SLM. A complex interaction between transient thermal history and the build-up of residual stress has been observed in the two laser scan strategies investigated. The temperature gradient mechanism was discovered for the creation of residual stress. The greatest stress component was found to develop parallel to the scan vectors, creating an anisotropic stress distribution in the part. The stress distribution varied between laser scan strategies and the cause has been determined by observing the thermal history during scanning. Using this, proposals are suggested for designing laser scan strategies used in SLM. Abstract:Selective laser melting (SLM) is an attractive technology, enabling the manufacture of customised, complex metallic designs, with minimal wastage. However, uptake by industry is currently impeded by several technical barriers, such as the control of residual stress, which have a detrimental effect on the manufacturability and integrity of a component. Indirectly, these impose severe design restrictions and reduce the reliability of components, driving up costs. This paper uses a thermomechanical model to better understand the effect of laser scan strategy on the generation of residual stress in SLM. A complex interaction between transient thermal history and the build-up of residual stress has been observed in the two laser scan strategies investigated. The temperature gradient mechanism was discovered for the creation of residual stress. The greatest stress component was found to develop parallel to the scan vectors, creating an anisotropic stress distribution in the part. The stress distribution varied between laser scan strategies and the cause has been determined by observing the thermal history during scanning. Using this, proposals are suggested for designing laser scan strategies used in SLM. Nomenclature:Specific

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Section: Introductionmentioning

confidence: 99%

“…Hodge et al [18] advanced this area by incorporating a multi-phase stress term using volumetric fractions, and a phase expansion term to account for volumetric shrinkage during phase change between powder and consolidated form.…”

Section: Introductionmentioning

confidence: 99%

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Parry

Ashcroft

Wildman

2016

Additive Manufacturing

421

287

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“…Two of the best-known, trusted and widely-cited general SLM/DMLS process models were produced by Kruth et al [9,37,38] at the University of Leuven (Belgium) and manufacturing scientists at Lawrence Livermore National Laboratories (LLNL) [39][40][41][42][43] in the United States. Both research teams developed comprehensive analytical thermo-mechanical models of the SLM/DMLS process, which are based on first principles, basic energy balances, phase changes, material properties, material states and part geometries, among many other physical phenomena.…”

Section: General Slm/dmls Process Modelsmentioning

confidence: 99%

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

2017

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Abstract:A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of the literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion and material models), direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization and post-processing), experiment development (methods for evaluation, optical and mechanical process monitoring, imaging and design-of-experiments), support structure optimization and overhang feature design; approximately 143 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs and potential future research directions are discussed in-depth in light of the present review.

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“…These modeling studies can be sorted into several subcategories, as shown in Figure 7. Two of the best known, trusted, and widely cited general SLM/DMLS process models were produced by Kruth et al [9,[37][38] at the University of Leuven (Belgium) and manufacturing scientists at Lawrence Livermore National Laboratories (LLNL) [39][40][41][42][43] in the United States. Both research teams developed comprehensive analytical thermo-mechanical models of the SLM/DMLS process, which are based on first principles, basic energy balances, phase changes, material properties, material states, and part geometries, among many other physical phenomena.…”

Section: Process Modeling and Simulationmentioning

confidence: 99%

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

Patterson¹,

Messimer²,

Farrington³

2017

Preprint

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A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce fulldensity metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion, and material models), direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization, and post-processing), experiment development (methods for evaluation, optical and mechanical process monitoring, imaging, and design-of-experiments), support structure optimization, and overhang feature design; approximately 140 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs, and potential future research directions are discussed in-depth in light of the present review.

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Implementation of a thermomechanical model for the simulation of selective laser melting

Cited by 283 publications

References 18 publications

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

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