Steven Sirman - Tata Steel Automotive, UK
Steven's primary function within Tata Steel Automotive is as a design engineer using FEA extensively to guide the design process to practical, high performing, low cost solutions, in addition to project management and programming. His responsibilities include:
Highways Safety products in Tata Steel. This involves extensive use of FEA crash simulations. We use Dyna for these simulations. I do not create the Dyna models myself, others in the team create and run the models, but I generate the designs and review the simulation results, using these to lead the systems development. I also lead the correlation exercises to ensure we gain maximum benefit from test data to continuously improve our modelling capabilities.
Two large company database applications. One is related to the highways safety work and acts as a drawing control system. Users have different access rights and the system has the capability to have drawings (Autocad and their pdf prints) uploaded into the database and electronically checked and approved. The system has full version control and users can download drawings with the knowledge that it will be the latest release. The system also contains a variety of documents such as reports and contains information about the physical tests carried out including photos and videos. The database groups all of this information within safety barrier designs, so it is easy to find information required about a particular barrier and bulk download anything that is required. The database can be accessed from various Tata Steel sites and offsite providing the user has internet access. The other database is similar and related to patents. Tata Steel’s IP department upload all patents generated by any company that are relevant to Tata Steel into the database and these are distributed to Tata Steel experts throughout Europe to review and comment on.
Replacing Test with Simulation in Highways Safety – The Tata Steel Journey
Tata Steel (formerly British Steel) has been involved in highways safety products for over 50 years. It started by supplying safety fences and bridge parapets to designs available for any company to manufacture and supply. These products had been developed using a test based programme, without the use of simulation and relied on a small number of physical crash tests to help create the designs and further crash tests to achieve acceptance for use on the UK highways.In 2001 the company took the decision to start development of its own highways safety systems. An automotive group in the company had the capability of running crash simulations for the development of vehicle structures. This seemed an ideal opportunity to use this skill base to help the development of the highways safety systems using the same crash simulation expertise.Initially these unfamiliar simulations caused a number of difficulties to be overcome. The impact conditions are somewhat different from the standard automotive impacts including; high speed – 110km/h; angled impacts – 20°; sliding friction – the vehicle runs along the barrier at high speed; large physical models – up to 400m in length; and long durations – event times ranging from 400ms for cars to 1.5s for HGVs.
These initial problems were overcome alongside the development of the safety systems. Physical tests were carried out with instrumentation placed on the barriers and the vehicles to allow measurements to be taken for improved understanding of the event and to allow correlation of the simulation models. These physical tests were both at component level e.g. individual posts and full scale testing e.g. Rover75 at 110km/h into 200m of safety fence.As more and more safety systems were developed, providing further test data, the simulation expertise and accuracy have been continuously improved allowing the typical test pass rate from around 30% prior to simulations to rise up to a typical pass rate of 90% and in some cases 100%.With this significant improvement in the simulation capability, the topic of using these simulations to improve the overall safety of highways was brought up in European standard committees. A computation mechanics group (CME) was formed as part of the European highway committees in order to review the capabilities of simulations and the possibilities of using them to prove some systems instead of testing. Tata Steel was part of this group and helped to produce guidelines for carrying out such simulations.
More recently as computation power has increased, improvements have been made to more detailed parts of the simulations to yet further increase the accuracy of the predictions e.g. the detailed modelling of pre-clamped bolted joints. This increased accuracy that Tata Steel is now able to achieve has led to its first CE marked acceptance of a modified system based on simulation alone.For such a complex event, having a completely new system validated by simulation is still some way off, but Tata Steel is now able to prove varying degrees of modification to existing systems. The next step is to make use of this to gain acceptance on the highways without the need for further crash testing.