‘Rising to the Post-Covid Challenge – How One UK Aerospace Engineering Services Company Has Adopted MSC Apex’
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Introduction
The global pandemic has hit our lives in ways that could not have been imagined previously. We have had most of our personal freedoms curtailed to stop the spread of this horrible disease. Our daily news is filled with stories of the sacrifices we have all had to make personally, and as a society. For many of us as engineers, our work has been significantly impacted, through economic constraints, reductions in manufacturing demand and company-wide remote working. Coupled with the additional uncertainty of Brexit, many companies have taken a very cautious approach to future development.
One area which has been hit harder than most is the aerospace industry. With limits on travel, the number of passengers in the air has fallen to previously unseen levels, which has placed the airline operators and aircraft suppliers under significant, sustained pressure. According to Forbes, Ref [1], international flights in 2020 saw a drop of 68% compared with the previous year, with domestic US flights falling by 40%. The figures for the rest of the world are far worse. However, recent reports have suggested that, as the effect of the vaccination program becomes more widespread, the industry will bounce back, with market intelligence suggesting that double-figure growth will return by 2022.
Airframe Designs Ltd. – Typical Aircraft Development Structure
Airframe Designs Ltd.
One player with their roots planted firmly in the aerospace supply chain is Airframe Designs Ltd, an engineering services provider based at the Blackpool Airport Enterprise Zone in the UK. Founded in 2009 by Jerrod Hartley, the business has grown a strong team of aerospace engineering specialists, and concurrently support a wide range of aerospace and defence projects. The core business is aviation safety, supporting UK CAA and EASA Part 21J design organisations to certify structural changes and repairs to flight structures. Historically, their skills have been in very high demand due to a shortage of experienced aerospace stress engineers, both in the UK and globally.
AFD works across multiple industries with an emphasis towards the aerospace, defence, and special mission sectors. They also work on a range of platforms and products including aircraft, rotorcraft and many types of interior structures. Commercial projects are numerous and have included bespoke VIP galley upgrades, narrow-body aircraft seat design, and various antenna installations to support avionic upgrades. For the special mission sector, AFD has certified a family of helicopter lifting baskets for human external cargo to access high-voltage power lines. Military projects have included support to ejection seat sled testing, UK Puma helicopter upgrades, and design activity associated with 6th generation fighter aircraft, Ref [2].
There are many areas of expertise, which AFD employ, to ensure the success of these projects. These include (i) employing static analytical methods to assess airframe structures, (ii) fatigue/damage tolerance assessment to ensure continued airworthiness, (iii) vibration assessment, especially prevalent for rotor and spacecraft and (iv) regulatory compliance to ensure that design changes meet the necessary airworthiness requirements.
However, one area which underpins all this work, is in the application of an effective FEA strategy to yield a detailed understanding of structural behaviour in a virtual environment. In short, demonstrating a high level of FEA application is a first step in any development work. Anything less than this is simply not an option – like a house of cards, if the FEA is wrong, then it is all wrong.
Airframe Designs Ltd. – VIP Galley Upgrade
AFD’s Journey
The UK leads the world in the development of flight vehicles, with the advent of the next-generation fighter aircraft just one example. Equally, the manufacturing industry is going through a digital transformation with the deployment of new methods to ensure sustained, high quality output whilst chasing down efficiency gains wherever possible. Couple this with the potential post-Covid bounce-back, and it becomes even more imperative for companies at all stages in the supply chain to be at the forefront of new technology to ensure continued success.
The global pandemic, and its impact on the aerospace industry, was a catalyst for AFD to re-think many of their existing processes and development methods, as a means of preparing for the bounce-back. This was born out of several factors – the ability to offer clients higher value from early concept through to critical design review, an opportunity to upskill and invest in the engineering team as part of their AS9100 quality framework, and an overall desire to be more agile in a tough competitive marketplace.
AFD had been reliant on a number of legacy FEA programs for the past decade, and assessment of contemporary methods highlighted many new platforms and toolsets, which were now available and could improve AFD’s overall analysis offering. As part of a growth and development mindset, AFD performed a significant review of the modern FEA software market. The bulk of the aerospace market relies on the industry standard FEA solver, MSC Nastran, both for regulatory compliance and the ability to interact with other parties using a common data format. This meant that any new toolset must support this data format.
AFD looked at many different FEA toolsets, either directly, or through the experience of their sub-contract supply base. Any potential purchase would require significant research and validation to ensure that time and investment was well spent. This was based upon (i) ability for integration into their current workflow, (ii) potential time savings and efficiency gains to be made, (iii) ability for both early and mature concurrent design update ahead of manufacture, and finally (iv) ease of learning and ability to become productive for both specialists and occasional users.
Discussion with numerous CAE/FEA software vendors showed the development in capability and deployment of many different toolsets over the past decade. It became obvious to AFD that MSC Apex, Ref [3], a contemporary, next-generation CAE platform developed by Hexagon/MSC Software, was gathering pace within the aerospace industry. Through initial contact through an aerospace industry event, AFD engaged Evotech CAE Ltd, Hexagon/MSC Software partner and dedicated MSC Apex training provider, to help with their initial assessment, through an offload development project.
Boeing 737 Stowage Compartment – CAD Definition
A Side Note on Aerospace FEA
Much of today’s FEA software had its beginnings in the aerospace and space sectors. The ability to predict and optimise the ‘pre-production’ performance for mission-critical structures has been imperative since the early Apollo missions of the late 60s. As this technology has advanced, FEA has made its way into many industries, and is now commonplace in the design and development of every modern vehicle from planes, trains, and automobiles, through to pretty much every consumer product in our homes.
The aerospace and related industries give rise to some of the largest, most complex FEA models being developed today. A full aircraft model will often consist of many layers of assembly, sub-assembly, and part, often reflecting various idealised levels of the CAD design data, connection strategies and elaborate material representations. Couple this with hundreds or thousands of (and sometimes more) load cases, and you have an analysis strategy that requires considerable design and implementation to be successful. Consequently, there are many, many data checks that need to be performed on both the input model/loading data and the output result. The model verification task is very often OEM-specific, but generalised forms are available to help, Ref [4].
While the democratization of FEA is in full force, enabling engineers with less direct FEA experience to be productive, the days where ‘black-box’, ‘meshless’, ‘stress by colour’ and even generative design approaches are some distance away from being useful in a robust aerospace development environment.
These are some of the factors which have resulted in legacy aerospace FEA being very time consuming, laborious, and prone to error, if the appropriate verification approach is not followed. Many, many development projects have been hamstrung by slow, difficult to use software, with models that are painful to build, and even more painful to change, with results that are simply too late in the development process.
For AFD, a change from the legacy methods of old, and a pivot to the next-generation model development and analysis paradigm was imperative.
Evotech CAE Online Training – ‘Intro to FEA with MSC Apex’
Aircraft Galley Structure
Once an offload consultancy project had been completed by Evotech, with considerable efficiency gains and flexibility demonstrated against AFD’s legacy workflow, an in-house comparison was undertaken. This looked at a typical aircraft galley structure, a Boeing 737 stowage compartment, constructed of lightweight metallic and composite sub-structures, detailed joint definition and the appropriate loading. Client CAD was made available for detailed assembly definition and idealisation, dependent on the downstream meshing strategy.
AFD engineers took initial MSC Apex training using Evotech’s 12-hour online training course ‘Intro to FEA with MSC Apex’, which gave the requisite skills to hit the ground running, followed by bespoke Evotech/Apex training in the application of specific galley structure FEA. Once enabled, AFD Lead FEA Engineer, Bill Thorne, performed the model build and analysis in MSC Apex. Comparison of the main build steps was made with legacy tools, either in-house, or with the support of external sub-contract resource.
Boeing 737 Stowage Compartment – FEA Model Detail and Output
The main steps in the FEA model build were,
- Assembly Rationalisation
- CAD to Mesh
- Model Connections and Properties
- Load Case Generation
- Client Design Update 1, 2 & 3
This workflow allowed i) the effectiveness of model build, but also ii) the flexibility offered by MSC Apex in handling 3 typical design updates to be seen. The resultant model was prepared for external MSC Nastran analysis, as per client requirement.
The discrete steps and total model development times are shown in the chart. MSC Apex proved to be significantly more efficient than Patran, the legacy AFD toolset, but also Altair Hypermesh and Siemens FEMAP (where build data was provided by sub-contract resource), two other popular FEA model build toolsets used in the aerospace industry.
Three interesting observations could be made by this comparison,
- The MSC Apex build was performed by engineers with minimal product exposure and training, compared with significant exposure to all three legacy tools.
- The Apex model build time took less than 3 days whereas using legacy toolsets were all around 8 days or more.
- The efficiency gains made using Apex could translate into more time optimising a product, rather than simply verifying a non-optimal initial design, as would have been seen with legacy toolsets.
Boeing 737 Stowage Compartment – Model Build Time Comparison
There are many reasons why Apex was shown to be more efficient than legacy tools, based around an ‘easy to use, easy to learn’ user interface, several next-generation CAE-specific, patented technologies, and a Python scripting capability, which allows customisation of the environment.
In terms of the stowage compartment FEA model build, the main technologies which gave an advantage were,
- CAE-specific ‘Direct Modeling’, which allows powerful geometry editing, idealisation, and mesh control, in a manner unseen in legacy toolsets.
- ‘Generative Model Update’, where any change to the underlying CAD definition resulted in upstream model changes (such as mesh, properties, and loading) to update automatically.
- Python tools to allow automation of several build aspects, including mid-surfacing/composite lay-up generation directly from source geometry, and fastener connections.
- ‘Analysis Readiness’ using the embedded Apex solver to ensure i) component verification during build and ii) full assembly verification to ensure that the external MSC Nastran analysis of the full assembly would run first time.
For additional examples of Apex efficiency, we have downloadable CAD data and the associated Apex model build steps given in Ref [5].
So, What Does This Mean to Airframe Designs?
MSC Apex allows AFD to achieve far greater efficiency for their FEA modeling and simulation tasks for both new and existing structures. Time saved allows for effort to be focused on different areas of the design process, which simply would not be possible using legacy methods and toolsets. Clients can be assured that their development goals can be achieved earlier and with reduced risk.
The next steps for AFD’s FEA development process will be to implement Apex-specific Python training to allow bespoke workflow development for model build, verification, and down-stream post-processing, ultimately leading to optimised structures, faster.
“Compared with modeling the structure using legacy software, the model build time was reduced significantly… and the time saved in this process was then utilised to help the customer fix issues concurrently via the model”
Jerrod Hartley CEng FRAeS, CEO, Airframe Designs Ltd.
“Models developed in legacy software can be difficult to adapt or re-model, as a design evolves… In Apex you can simply modify the underlying CAD, and the model updates automatically”
Bill Thorne IEng AMRAeS, Lead FEA Engineer & NAFEMS PSE, Airframe Designs Ltd.
A Side Note on Evotech CAE Ltd
Evotech Computer-Aided Engineering Ltd is an engineering consultancy and Hexagon/MSC Software partner based in the UK, specialising in product development, technical sales, and training in advanced Finite Element Analysis (FEA). With a background predominately in the Aerospace industry, Evotech CAE are expert in strategic model development, analysis, and structural optimisation.
Evotech CAE’s Director and Lead Engineer, Dr Steffan Evans, has over 20 years’ experience of advanced FEA and holds a Doctor of Engineering degree in Structural Optimisation, Chartered Engineer status, and NAFEMS PSE Certification at advanced level (including Non-Linear Analysis, Composites, Optimisation and FE Model Verification).
References
- ‘The Aerospace Industry Is Preparing For An Upturn’, M. Fawzy, Forbes Councils Member, June 2021, https://www.forbes.com/sites/forbesbusinesscouncil/2021/06/17/the-aerospace-industry-is-preparing-for-an-upturn
- ‘Case Studies’, Airframe Designs Ltd., https://airframedesigns.com/case-studies/
- ‘MSC Apex Overview’, Evotech CAE Ltd., https://evotechcae.com/apex/#overview
- ‘MSC Nastran Linear Static Analysis User’s Guide, Chapter 10 ‘Model Verification’, Hexagon/MSC Software, https://help.mscsoftware.com/bundle/MSC_Nastran_2021.2/page/Nastran_Combined_Book/linear/modver/modver.xhtml#TOC_Model_Verification
- ‘MSC Software ‘Simulating Reality’ Conference – Apex Model Build Challenge’, Evotech CAE Ltd., https://evotechcae.com/msc-software-simulating-reality-conference-apex-model-build-challenge/
Images courtesy of Airframe Designs Ltd/Evotech CAE Ltd.
This article has also been published in Develop3D (link) and North West Aerospace Alliance ‘Plane Talk’ (link).