applications ➤


expensive to manufacture on an individual user basis. Te soſtware allows us to speed up the entire design verification process and gives us confidence that our products will stand the test of time.’ Honeywell is involved with several AM


programs. Some programs, such as DARPA Open Manufacturing, are developing a suite of tools to simulate the process. Others are developing technologies to help understand what it takes to make specific products to meet aerospace requirements. Peralta said: ‘Te overall goal is to understand the physics of the process and to define the process parameters that yield a part meeting dimensional and structural requirements to meet all aerospace safety and quality standards.’ Tese programs have used simulation


soſtware from the ESI Group to model the powder spreading, followed by the melting of the powder with all the different phenomena governing the fluid flow, and ending with the solidification of the molten metal. Solidification results in high residual stress caused by the large thermal gradients that develop during the process. Peralta said: ‘We have been able to simulate the melting of the powder, including all the relevant physical phenomena that play a part on the formation of the melt pool size and shape, and then we have been able to simulate the deformation that arise because of the residual stresses that develop during the process.’ Te huge range of phenomena to simulate


means that challenges remain to understand how most efficiently to obtain the correct solution. Peralta added: ‘Te biggest challenge has been to understand all the knobs that need to be turned in the soſtware to model the correct physics to obtain the desired results and, once we obtain those, to be able to interpret them correctly given that oſten, the obtained behaviours go against our preconceived notion.’


Designing the future Engineers at the Manufacturing Technology Centre (MTC) take prototypes from the research arena and use industrial equipment and cutting-edge simulations to


In Evolve rendered images of the optimised lug, side and front views


mature these designs. Tey work with a range of materials, including steels, titanium, aluminium alloys and nickel super-alloys, to create complex geometries through AM. Te engineers have used simulations to optimise a particular AM technique known as shaped metal deposition (SMD). In contrast to powder-based AM techniques,


SMD has the capability to build new features on pre-existing components or allow a number of materials to be integrated into a single part. It is also a faster technique, but not as refined as powder-based processes. Similar to fusion welding, a mass of molten


metal is incrementally deposited on a surface. However, components manufactured through SMD contract as they cool down, causing internal tensions to accumulate, which results in component distortion, such as bending, when a straight edge is desired. Two strategies can be used to overcome


these distortions. One method is to predict the outcome of the design by modifying certain build parameters to minimise deformations and the other involves changing the design to counteract such deformations. Engineers at the MTC used COMSOL


Multiphysics to turn an existing model into a simulation app, which is based on a thermomechanical analysis of thermal stresses and deformation resulting from SMD thermal cycles. It can predict whether the resulting component will pass a range of acceptance criteria, based on the specific nuances of the application area. A major benefit of the simulation app


Analysis of the lug after optimisation 26 SCIENTIFIC COMPUTING WORLD


is its intuitive user interface, which means individuals and teams without a background in simulation can run their own tests and obtain results. Borja Lazaro Toralles, advanced research engineer of digital engineering at the MTC, said: ‘Tis meant that complex simulation models that usually required a specialist to run them now had an interface with a front-end that a designer could use. Te designers can work out how to manufacture a product by editing certain parameters, which frees specialist resources and gives a wider


range of alternatives to the designers.’ Within this app, users can test different


geometries and materials, alter the deposition path, change the heat source or apply varied meshing sequences. Te next step is to link a range of different


applications, including COMSOL Multiphysics, CAD, and statistical analysis soſtware, into one integrated workflow with an equally intuitive user experience. Lazaro Toralles added: ‘Te idea is that we would like to produce a simplified interface in the same vein as the simulation app we produced using COMSOL.’ Incorporating multiple pieces of soſtware


that are not designed to work together is more tricky than the simulation app development, but the team are working to make the workflow more robust and are working with designers to


THE HOLY GRAIL IS TO PRODUCE THERMAL HISTORIES THAT CAN PRODUCE THE REQUIRED MICROSTRUCTURE/ PROPERTIES AND OVERALL STRUCTURE


improve the interface, as well as taking a little design inspiration from the apps you find on mobile phones. Te engineers are also endeavouring to


improve simulations to more accurately predict specific properties in a range of materials – for example, to predict when cracks may appear in certain structures fabricated using SMD. Tere is still a long way to go to fully realise


the potential that additive manufacturing could offer the industrial world. Simulations are the driving force behind the push to make AM a mainstream technology, but such computational techniques must improve to meet the massive multi-scale issues and simulate the sheer range of phenomena required to provide a coherent picture. It’s a huge undertaking, but the potential advantages are equally awesome. l


@scwmagazine l www.scientific-computing.com


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