Simulate to innovate!

CiMFeb21Feature - altair1
CiMFeb21Feature - altair1

In Altair’s recent Virtual ATCx Composites webinar, vice-president of composite technology, Jeff Wollschlager, discussed the latest integrated multi-disciplinary simulation solutions used to develop composite products more efficiently in his ‘Introduction to the Design and Analysis of Composite Structures’ presentation.

 

Altair’s Composites Team’s primary objective is to provide composites solutions across our entire product suite and connect all our products to provide intuitive workflows using the absolute latest composites technology. We’re guided through what I call the composites solutions design pyramid which describes four main areas of development that we're actively working on.

Altair's vice-president of composite technology, Jeff Wollschlager

The first, and the absolute foundation of that pyramid is Advanced Material Model Development, where we’re working on creating highly predictive material models while we are additionally retaining computation efficiency. The next development block is Integrated Manufacturing and Structural Simulation. The goal here is to use the manufacturing simulation material, principally fibre orientations and residuals, in a structural simulation in order to improve the predictive accuracy and efficiency of the structural simulation models we're building.

Altair’s composites solutions team is focused on bringing and extending these fundamental technologies into the composites world. Here, we're offering a unique Composites Design and Optimisation methodology that produces some really interesting composite designs much quicker than other traditional methods.

And last but not least, our composite design certification development block produces an FEA integrated composites stress toolbox to perform traditional or classical composite calculations that you would use with your certification agency to substantiate the design you may have. So, let's talk about a bit about each of these blocks in slightly more detail.

Material property values

The Advanced Material Model Development block involves transitioning from a homogeneous isotropic world to a heterogeneous anisotropic one and becoming as comfortable with heterogeneous anisotropic material models as we are with homogeneous isotropic material models. We’re focusing on three main product forms in the continuous reinforced product world, mostly on unidirectional and woven product forms. Within these two product forms, the unique capability is actually the ability to bridge the scales from the homogeneous ply level to the constituent fibre and matric level and the ability to do that computationally efficiently and to obtain results at the constituent fibre and matrix level, such that we can obtain significantly more accurate material models.

It’s the same in the discontinuous reinforced product world, where we’re focusing on reinforced injection moulded material and doing the same. We’re describing the heterogeneous anisotropic nature of these materials characterising that heterogeneous anisotropic nature and accurately and computationally efficiently developing material models to describe all of that for you.

Altair’s simulation solutions have been used on the AC75 Luna Rossa Prada Pirelli Italian sailboat Image credits: Luna Rossa Prada Pirelli, Studio Borlenghi

Ultimately, it's about reducing the time and cost in the design process due to incomplete material understanding and the inability to highly accurately model these materials and bringing that to the forefront. It's also about reducing the amount of experimental data required to build these models - not necessarily bringing it to zero, but absolutely reducing what’s required in order to develop these highly accurate material models. Increasing simulation accuracy while we are doing all this and retaining computational efficiency.

The principal product we’re using inside the Advanced Material Model Development block is what we call Altair Multiscale Designer, which allows for the exact same material models to be used within all commercial implicit and explicit solvers. This is tightly integrated into our own OptiStruct and Radioss solvers, but the exact same material models are also available in other commercially available solvers too. It’s exactly the same material model in exactly the same code we’re using that through the User material capabilities in all of the codes.

When we talk about ‘integrated manufacturing’ and ‘structural simulation’, it's all about being able to efficiently build these structural simulation models while we are bringing manufacturing information into the structural simulation in order to improve our predictive accuracy of these structural simulation models.

Adept at adaptation

The three main areas of focus are firstly, the area of traditional or automated layup and infusion methods. Here, we’re working on integrating draping simulations to obtain fibre orientations and/or residuals into the structural simulation very quickly and efficiently.

Secondly, injection moulding - mainly in the reinforced injection moulding world but also unreinforced injection moulding. We’re again working on bringing into the structural simulation world, the fibre directions and the residuals - be that thermal gradients - and using them to understand warpage and residual stresses and strains, so that we can again improve the accuracy of those structural simulation models.

The third area is filament winding for pressure vessels, where we’re using filament winding simulation software, which again provides us with fibre orientations and/or residuals of various natures that we can bring into the structural simulation world and apply them to improve the accuracy of those structural simulation models.

A good example of a complete workflow in the integrated manufacturing and structural simulation world is the Altair Injection Moulding Solution Workflow. This involves three main elements. We’ve just released Inspire Mold, which is a fantastic moulding simulation product which allows you to do fill, pack, and cool simulations in addition to all that you can get your fibre orientations after a filling simulation.

Multiscale designer is used in concert with the moulding simulation to develop an heterogenous anisotropic material model for that particular reinforced injection moulded material and we then bring both of that information together in the pre-and post-processing world, which is HyperMesh and HyperView. HyperMesh is where we build the structural simulation model; HyperView where we are post-processing that particular structural simulation model. We’re using OptiStruct to perform the solution, whether it's a warping simulation or a strength simulation, including warp residuals in that strength simulation for ultimate load-carrying capability.

Systems within systems

What's unique about this particular simulation workflow is that it is wholly-contained from the beginning to the end within the Altair product suite. It’s solving the interoperability problem that you might have to go through if you were going to ‘a la carte’ the pieces of this from other commercially available offerings.

Going into Composite Design Optimisation, again using traditional capabilities in the concept design optimisation role: namely, topology optimisation which in the composite optimisation world it gives us the part shape. We’re using that exact same technology to actually tell us what the part shape should be, but we need to go a little further with composites. Once we know we have a certain part shape we can make up that part shape with any number of composite plies and any number or orientations and thicknesses that we need.

We’ve extended our optimisation capabilities into two primary technologies. The first one in the composite concept design optimisation world which is called composite free-size optimisation which is really focused on trying to describe what is the most efficient ply shapes. Just like topology is synthesising a structure, we’re actually synthesising ply shapes that make up that structure with that particular concept design optimisation technology.

Once we've interpreted our concepts, we can get into the detailed composite design optimisation phase. Here, we’re talking about composite size and shape optimisation. It's equivalent to the size and shape optimisation, but we put the word ‘composite’ on the front, because we’re talking about sizing ply shapes now, so it's going to principally answer the question: how many of each ply shape do I need to meet my engineering targets or my engineering requirements in terms of no fibre breakage, no buckling, maybe certain deflections, so bringing in those engineering requirements.

We’re also focused on bringing in repeat laminate technology and double-double laminates into this design methodology and you're going to see the ability to optimise with these double-double laminates which are theta, minus theta, phi, minus phi. ‘Ns’ type laminates, where we’re optimising on what is ‘N’, the number of repeats, what are theta and phi, what are angles in this double-double laminate, and using our optimisation technologies to solve for that.

The real difference in the unique aspect of these composite design optimisation technologies is the ability to synthesise these ply shapes. Shapes that you might not have intuitively thought of to make before, but are actually totally valid and can be manufactured. Why we are synthesising these ply shapes and optimising the ply angles and the ply thicknesses? To provide a modern robust composite design methodology that is different from traditional design methodologies in the world of composites.

Right tools for the job

Last, but not least, our development block of Design Certification is all about integrating composite stress toolboxes into a finite element architectural world. This has always been the kind of outstanding item of these stress toolboxes which exist in numbers across many companies. It's really interoperating within the finite element architecture or finite element information.

Altair has a unique opportunity since we acquired ESAComp, which is a fantastic composite stress toolbox that came out of a project initiated by the European Space Agency. We’ve acquired this technology and we are working on providing an integrated version of it inside the HyperWorks framework. It’s about solving the interoperability problem when exchanging information between your finite element models and your traditional composite sizing and certification calculations in order to really reduce the pain point there.

This FEA integrated stress toolbox will provide capabilities for composite beams and panels, and bonded and bolted joints for both design and analysis. It can handle linear static, nonlinear, buckling, first ply failure and even progressive failure of laminated structures. It's quite exciting to see this technology come in.

In summary, these are the four main areas we’re focused on developing. Hopefully, this gives you some insight into the vision and the roadmap of where we’re going. We should start seeing the fruits of our labours coming in with this version and beyond. I hope you enjoy it.

www.altair.com

https://www.altair.com/resource/composites-at-altair-atcx-presentation

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Altair [**]

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