Robert Roe investigates the use of optimisation software in modelling and simulation and its power to re-invigorate traditional manufacturing methods
Casting and moulding are some of the oldest industrial processes. But a process that to this day seems to be the embodiment of old-style ‘smoke-stack’ industry is being reinvigorated by optimisation software that allows engineers to define the manufacturing constraints early in the design process.
Computer aided engineering (CAE) that performs this kind of multi-objective simulation provides engineers with a much higher level of precision earlier – ultimately leading to a cheaper better performing product.
Traditionally the design of a product and its manufacturing where two separate processes; in larger projects this would often be handled by two completely separate teams with different levels of specialisation in their given fields. Ultimately, this meant that it was down to the experience of the users to identify potential problems that might arise later in the product development process. It is not an efficient strategy, for it costs companies time and money as they have to redevelop models or make several iterations of a design that would otherwise have been unnecessary.
Now CAE engineers can apply manufacturing constraints imposed by a specific process into the design phase of the product, which leads them to make better decisions about material distribution and how the design will transition from the simulation to a physical part or component in the real world.
One aspect of this which has been successful for all sectors of engineering is topology optimisation. This approach optimises a material layout within a given design space, allowing engineers to analyse a material distribution based on realistic physical loading, allowing them to reduce weight significantly, or increase overall structural performance for a given loading.
Dr Uwe Schramm, the chief technical officer for Altair’s solvers, optimisation and smart multi-physics solutions and strategy, said: ‘Topology optimisation gives you the optimal material distribution for a given loading; it is a kind of load path analysis.’
Schramm explained that if a user wants to use a specific manufacturing process – for example milling or casting – then they must acknowledge the manufacturing constraints introduced by using this process. Altair has put considerable time into developing its software package Optistruct, part of the HyperWorks software platform, so that users can include specific manufacturing constraints at the beginning of the optimisation process. HyperWorks is a multidisciplinary CAE software platform that includes modelling, linear and nonlinear analysis, structural optimisation, fluid and multi-body dynamics simulation, visualisation, and data management.
Schramm stated: ‘Doing a topology optimisation at the beginning of your design process gives you a material layout that gives you the opportunity to have fewer design iterations.’
He went a step further by explaining that, although a designer or engineer may have a specific idea for the basic shape of the part, topology optimisation can define a true representation of the necessary geometries for a given part. ‘We know of certain geometry conditions where if you make one wrong decision in your geometry, you can chase that wrong decision forever’ said Schramm. For this reason it is important that CAE designs include topology optimisation as early in the initial design phases as possible, so that a particular design does begin on the wrong path.
In addition to applying topology optimisation to understand a given loading and the impact that that will have on the final design, it can also be used to identify design changes that are necessary because of a particular manufacturing process and the specific constraints that are introduced through the use of this process.
Schramm explained that, in order to plan a design effectively, users can include manufacturing constraints in addition to the load paths to understand how these manufacturing processes might impact the strength of the given design.
Although failure to do so may not result in the failure of the part, it may exacerbate the fatigue and stresses imposed by the shape and composition of the material and the load that it is subjected to.
However, Schramm was keen to highlight that topology optimisation is not tied to a specific manufacturing process. Schramm said: ‘It helps you to get better-performing designs because you are using the material in the optimal way and it gives you a quicker time to market because you are starting with a material distribution that actually fits your loading conditions, your use case, and that gives you a better chance to find the right design.’
Schramm stated that it is a case of developing specific manufacturing constraints associated with a given process and integrating those with the other constraints specific to the design of the part.
Another aspect of optimisation technology is the application of mathematical optimisation principles to any aspect of the design process. Esteco developed modeFRONTIER, a multi-objective optimisation and design environment, to couple CAE tools for finite element, structural analysis and computational fluid dynamics (CFD). modeFRONTIER is a GUI driven software, written in Java that wraps around the CAE tool. It is used to perform optimisation of a given parameter by modifying the value assigned to the input variables, and analysing the outputs based on pre-defined objectives or constraints of the design.
Carlo Poloni, president of Esteco said: ‘Cost reduction, time reduction, and performance enhancement: all of these three major categories are touched by optimisation.
‘That may mean reduced scrap material or it may reduce the actual mass of the components; it may decrease the energy costs for the manufacturing. Really any parameter that you want minimise or maximise can be considered with an optimisation environment,’ said Poloni.
Poloni said: ‘We are independent of the code which is coupled to modeFrontier to do the simulation.’
Poloni commented that some optimisation characteristics are often present in the software packages that couple to modeFrontier, but Esteco software allows the coupling of multiple systems around any number of objectives and constraints. He sees this as critical to a multi-disciplinary optimisation process that can take manufacturing processes into account.
Poloni said: ‘If you want to bring to the highest level, it is important that we design for the manufacturing process. Instead of separating the two problems you may face them together and this has some important advantages because there are some components that can be built with a particular manufacturing process and some that cannot.
‘This means that you can design an optimisation process that is at a higher level because you can manage a complete process’ concluded Poloni.
Poloni stressed that to truly integrate engineering and manufacturing processes into the design of a part requires collaboration between the various teams or individuals that are responsible for these areas, something that has increased in recent years but that still must be improved for users to see the most benefit.
Poloni said: ‘ModeFrontier can help with that, because you may have different teams that deal with the functionality on one side and another team of people that deals with the manufacturability on the other side. If the two teams can effectively share information then you may end up with the complete process.’ ‘That really is the next challenge. More than the optimisation itself,’ Poloni concluded.
Poloni stated that part of the driving force behind Esteco’s continued success had been its mission to work with a wide selection of software packages and workflows. Poloni said: ‘We never wanted to get too focused on a single product; we think that optimisation is a horizontal technology that must fit different application areas.’
This has meant that the company has had to develop a means of integrating the various outputs from more engineering software codes so that they can be identified quickly and easily by the modeFrontier software.
Poloni explained that there are many ways that modeFrontier might interface with other software packages. The most tried and tested of these methods is to ‘extrapolate the variables to individual text files and this is done through a graphic interface.’
However with modern software platforms this can become very complex in short order, so Esteco has also established direct interfaces with more than 40 industrial software packages to date.
‘When a code has become more established at an industrial level, it has usually evolved to the point of having APIs that allow you to build a direct interface to the product. In those cases, you do not need any special coding. The parameters will actually be recognised by the software,’ said Poloni.
He explained that, in the majority of cases, Esteco will form partnerships with these companies because there is a mutual benefit as modeFrontier is enhancing the use of the software by enabling automation of multiple simulations.
Although manufacturing constraints con be considered at the very inception of a new product, not all manufacturing processes are suitable and some parts have to be produced in a specific way.
In recent years additive manufacturing, or 3D printing, has become a hugely popular topic, not only for consumer markets but also as the next big buzz word in many sectors of engineering.
Uwe Schramm said: ‘3D printing claims that you can manufacture everything, and this is not true. There are manufacturing constraints for 3D printing: you generally do not get a finished product out of 3D printing; it requires some additional machining; you need to drill holes because this cannot be accomplished using the additive manufacturing process.’
Schramm continued: ‘My personal view here is that, like materials and everything else in the world, the manufacturing techniques are going to compete with each other. He went on to give an example: ‘Casting a part a million times is going to be cheaper that using 3D printing a million times.’
This is largely because of the time and materials costs associated with production, but even when the cost of metal powders for additive manufacturing have been significantly reduced, the process of layering a design will always be a time consuming when compared to some traditional manufacturing techniques such as casting or moulding.
The future of optimisation
The future of optimisation, as with many areas of the CAE chain, lies with the integration of other processes to give a more holistic simulation that combines objectives in much the same way that optimisation can now include manufacturing constraints.
Altair has developed its Altair Partner Alliance to provide a broad portfolio of specialised solutions that would not necessarily be large enough to require standalone development. However, by integrating these with the HyperWorks platform, users can experience the full portfolio of Altair and its partners’ solutions through a single software licence.
Schramm said: ‘When the APA started we did not have CFD technology, electromagnetic simulation, fatigue simulation, and we recognised that we need this functionality in our portfolio to do multi-disciplinary design. So we created this partner alliance to bring their software in.’
In addition to the APA, Altair also seeks out relevant technologies which are then added into the HyperWorks platform. He gave a recent example of Altair’s acquisition of Click2Cast, which aims to increase the usability of simulation software for casting industry.
Schramm explained that Altair choose to acquire this company because of the specific feature that the software brings in the areas of feasibility testing, which can now be included early in the deign process.
‘If you get a certain material distribution you recover some geometry, with casting simulation you can decide “can you cast that part?”’ Schramm explained that, if there is some reason why it is not possible, then you can ‘make changes to your optimisation setup which will generate a part that is much more suitable’ to the specific manufacturing constraints imposed by that process.
The nature of Esteco’s software platform means that it is not primarily concerned with acquisition, but much more with the effective integration of CAE tools into the modeFrontier platform. Poloni stated that the company is committed to offering as open a platform as possible to its users, from being able to use many CAD or CAE inputs but this also extends to the optimisation strategies and algorithms available for its users.
Poloni said: ‘There is no free lunch theorem: that means that there is no optimising strategy that is good for every single problem. As we don’t know the answer in a specific case, we believe it is important to offer more than one option in terms of optimisation because it is a search activity.’
‘We give to our users the ability to use different optimisation algorithms and the ability to switch between them without any effort from the user.’
One aspect that Poloni stressed as an area of innovation for the future is around the collaboration of different teams in the design process. ‘As soon as the process becomes more complex more people get involved ad that means that you have to have collaboration tools in place, and for that reason we are now offering the enterprise solution SOMO,’ said Poloni.
He explained that this allows companies to have different development teams working on the same project. This would depend on the internal strategy for collaboration within a specific company: ‘They have to start sharing models instead of specifications,’ Poloni pointed out. Such collaboration, he concluded: ‘Will probably make the design for manufacturing possible, because you may have different individual experts in their field sharing through the modeFrontier environment.’