The automotive industry, more than ever, has to cope with the following obligations:
- To push innovative technologies;
- To reduce development times;
- To reduce costs.
These obligations must attend to and provide improvements in the following:
- Safety (e.g. pedestrian protection and occupant safety);
- Environmental Protection (e.g. reducing CO2 emission);
- Handling and Comfort (e.g. vehicle dynamics, vibration comfort, and acoustic properties).
Computer Aided Engineering (CAE) tools play a key role in creating an improved design by simulating and analysing new vehicle concepts intended to fulfil these requirements. They enable optimum use to be made of information in the various design phases, from the conceptual design phase to the detailed series-development phase.
Although the design and validation process differs from company to company, the importance of early functional coverage is universal. In the early development phase, there is an emphasis on fast evaluation of different concepts. Quickly and accurately understanding relative trends is most important. In this design phase there are frequently no CAD models available. By the detailed series-development phase, CAE models used for prognosis must be highly accurate because, in this phase, relative results are no longer sufficient. Results must be absolute.
Therefore, in 2005 NAFEMS proposed and initiated a project with the aim of reviewing the current use of CAE and studying ways to improve its use. This was the start of the AUTOSIM project.
The aim of AUTOSIM was to focus on three topics. These were as follows:
- Integrating Simulation into the Development Process
- Materials Characterisation
- Improving Confidence in the Use of Simulation
The overall goal was to identify Best Practice (BP) and Breakthrough Technology (BT). Because designers may have different interpretations of these terms, the consortium suggested the following definitions:
- Best Practice (BP): How we currently make the best use of available technologies and procedures to tackle engineering problems.
- Breakthrough Technology (BT): Novel or revolutionary technologies and procedures needed to solve engineering problems successfully in our vision of the future.
AUTOSIM established an international team of leading experts representing much of the European automotive industry. They developed a preliminary set of Best Practice Guidelines, standard analytical procedures and research strategies. They then consulted with the wider automotive industry to gain feedback on the preliminary documents and establish credibility of the final documents. During the AUTOSIM project a series of workshops were held in which speakers were invited to present on BPs and BTs in the three AUTOSIM discussion areas of Integration, Materials and Confidence. Final authoritative versions of these Best Practice Guidelines, standard analytical procedures and research strategies were delivered and widely disseminated.
The main project conclusions are as follows:
- Today, simulation is typically used under predefined, predicted, and controlled conditions. The current state of the art seems to couple two disciplines, such as Structural Analysis and Computational Fluid Dynamics. But a car — tested as it would be driven — should have been tested by simulation for a combination of concurrent factors, such as Occupant Safety, CFD, Multi-Body-Systems, Structural Dynamics, Fatigue, and the like. Simulation and Analysis should become more comprehensive. We should proceed in the areas of Multi-Physics and Multi-Disciplinary Optimisation.
- It has been determined from the work carried out in AUTOSIM that the principal areas of interest and concern regarding CAE confidence relate to the validation of CAE models, CAE staff training, the quality of model material data and the discretisation of CAE models.
- With Materials Characterisation clearly of high importance, a methodology is needed to ensure that characterisation of materials is reliable, accurate and achieving best practice; this should also ensure that novel materials can be introduced as early as possible. Development of an extended database holding not only basic material properties but also essential information regarding, for example, the effect of forming processes on material behaviour is essential. Close collaboration between vehicle manufacturers, material suppliers, testing houses and software developers will be required to achieve this.
- FE models are approximations of reality, but must be realistic and capture the physics of the situation. Inclusion of Uncertainty will boost the Level of Confidence. Uncertainty stems from the physics and must be considered. The availability of powerful and low-cost computers able to analyse parallel considerations will support this paradigm shift dramatically.
- In the future, automatically generated models should speed up the Conceptual Design Stage. The need is for tools that will allow a simulation analyst to do more analysis more quickly during the early stages of the design process, and to do them in a well organised way. For example, a designer could develop parameterised car body models to quickly study design variants when CAD data is not available. The use of these parameterised models, together with sophisticated optimisation tools, will and must play a significant role in the future.
- How to Store Data and how to Retrieve Knowledge. Tools should be set in place to take advantage of knowledge gained from analysis runs from designs of car predecessors, or simply from previous analysis runs of crash, NVH, durability, etc.
In the future, CAE needs to take into account extended distributed development environments to address Product Life Cycle Management. Tools and Processes must be integrated, with consideration given to the OEMs and Suppliers, recognising their knowledge and resources.