© 2016 High Value Manufacturing Catapult. All rights reserved.

The process of additive layer manufacture (ALM) consists of selective

laser or electron beam melting of specific regions in a bed of metal

powder to build a component sequentially from hundreds or thousands

of horizontal layers. Conventional ways of modelling ALM processes

have failed to meet industrial demands due to the huge computational

effort required and the associated challenges with numerical

convergence.

The MTC Simulation Group has addressed this limitation through an

MTC Members’ Collaborative Research Project aimed at developing an

innovative and robust, rapid predictive methodology for powder-bed

ALM technologies. The methodology has been validated and applied to

complex industrial components to predict distortion and residual

stresses as well as give indications of crack initiation risks.

The implementation of the developed methodology in the design of ALM

is typically expected to:

• reduce the number of physical prototypes by 50%;

• decrease the lead time for design by 50%;

• reduce the cost of manufacture by 25%.

Numerical Modelling of Powder-Bed Additive Layer Manufacturing Technologies

March 2016

Integration of Powder-Bed Additive Layer Manufacturing Simulation on anIndustrial Scale

MTC Case Study 30876-001

Figure 1: Component produced by 3T RPD Ltd with the

application of ALM

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© 2016 High Value Manufacturing Catapult. All rights reserved.

Overview of Validated Methodology

The innovative part of the developed methodology lies in both the

combination of analytical and numerical physically-meaningful

analyses, as well as being able to scale the created solutions from the

micro-scale to the macro-scale. A concept of using a specimen is

introduced to accommodate the micro-to-macro scaling and calibrate

the analytical thermal model. This allows the mechanical solution to be

numerically derived without the need for a micro-thermal analysis,

which would otherwise be prohibitively lengthy.

March 2016

MTC Case Study 30876-001

Figure 2: Rapid ALM Predictive Methodology

Figure 3: Metal 3D printed bicycle frame manufactured by Renishaw

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© 2016 High Value Manufacturing Catapult. All rights reserved.

Key CapabilitiesThe key capabilities of the methodology can be summarised as:

• Residual stresses and distortion can be predicted during ALM

fabrication.

• Industrial components can be simulated in less than 12 hours using

a desktop computer with Xeon® X5650 @ 2.67Hz processors.

• Different materials and process parameters can be incorporated for

selective laser melting and electron beam melting.

• Alternative user-defined toolpath strategies can be modelled that will

minimise distortion and residual stresses.

• It has been applied to a number of industrial components to reduce

and compensate distortion, reduce the risk of crack initiation and

understand the effect of the induced residual stresses on the

component life expectancy.

• ALM simulation results have been integrated into a manufacturing

process chain, including post-processing technologies, such as heat

treatment, machining operations and surface treatment & hardening,

in order to understand the overall component mechanical behaviour

and predict its structural quality.

March 2016

MTC Case Study 30876-001

Figure 4: Application of an aerofoil –prediction of residual stresses in ALM

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© 2016 High Value Manufacturing Catapult. All rights reserved.

The methodology has been successfully used in the following

applications:

• Distortion prediction of thin tube structures.

• Distortion reduction of a lightweight bracket by improving the

geometrical stiffness.

• Distortion reduction in the blade of an aero-engine by using a

geometry compensation technique (see Figure 5).

• Prediction and reduction of tensile residual stresses, thereby

improving the service life of an aerofoil.

• Predictions of crack initiation risks during fabrication and their

mitigation using geometrical modifications for a gas turbine

component used in the power generation industry.

• Selection of appropriate materials in the design of components

subjected to thermo-mechanical loading.

Simulation Applications

March 2016

MTC Case Study 30876-001

• Aerospace• Medical Devices• Power Generation• Automotive Industry• Railway • Defence

Figure 6: Distortion prediction of a specimen using a range of metals

Figure 5: An example of applying a geometry compensation strategy based on FEA predictions where component distortion was reduced

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© 2016 High Value Manufacturing Catapult. All rights reserved.

Simulation of Manufacturing Process

Chains of Additively Manufactured Blade

The MTC has successfully simulated two manufacturing process chains

for an additively manufactured blade by integrating the novel

methodology into a process chain simulation platform. The final

distortion and residual stresses were predicted and used for the life

assessment of the blade. The simulation results contributed towards

making key decisions during the design and manufacture, including

geometry compensation to reduce distortion and mitigate risks of crack

initiation in service.

March 2016

MTC Case Study 30876-001

Figure 7: Simulation of a manufacturing process chain. The figure shows predicted residual stresses using the same legend scale in all illustrations

Figure 8: ALM blade followed by post-processing - Morris Technologies

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© 2016 High Value Manufacturing Catapult. All rights reserved.

The MTC has developed and matured simulation methodologies and techniques that have been applied to

reduce distortion and improve service life of high-value ALM parts. More maturation in modelling and

simulation is required to address other engineering aspects in ALM and further improve the quality of the

parts, as shown in Figure 9.

March 2016

MTC Case Study 30876-001

Figure 9: Technology roadmap for the maturity in modelling and simulation of additive layer technologies - 2016

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