Management guru Robert Townsend once wrote that consultants are people who borrow your watch, tell you what time it is, and then walk off with the watch.

Frazer-Nash Consultancy, and Dan Bray in particular, would beg to differ with that negative assessment.

Although he has only been working as a full-time employee for two years, Bray’s association with the company goes back further. Before he went to Cambridge University to take a four-year degree in mechanical engineering, Bray had already been accepted on the company’s undergraduate sponsorship scheme while studying for his A Levels.

Apart from providing him with a bursary, the scheme promised him the opportunity to work on some exciting projects during his degree, and the option to join the company after he graduated.

After two years of studying a variety of engineering subjects, Bray found himself attracted to the study of how finite element methods can be applied to solving complex structural analysis problems in mechanical engineering.

His love of the subject was put to good use during one summer assignment at the company. Frazer- Nash was sponsoring a powerboat racing team and Bray was given the chance to perform an engineering analysis on the structure of the boat.

To do so, he built a finite element model of the boat and ran it through the company’s proprietary hydrodynamic simulator to simulate the wave flow around it as it travelled at different speeds through the water. Once the mathematical model had been completed, Bray compared the results with physical measurements he had taken from the boat to assess the accuracy of the model.

‘Although it was an in-house project, I was given the sole responsibility to ensure that it came in on cost and in time. I took the project from an initial proposal, which I wrote myself, through to completion,’ said Bray.

Having successfully finished his work on the water, Bray’s next challenge was up in the air. Again, his passion for modelling was brought to the fore, as he was asked to create a computer model to optimise the production of composite wings for aircraft.

Composite materials in the aerospace industry must be manufactured costeffectively and efficiently, and the autoclave is the principal equipment used to produce them. It can be used to accelerate the curing, hardening and drying of large components such as the wing and fuselage components of aircraft.

Inside an autoclave, components such as wings are subjected to high pressure and temperature in an atmosphere of circulating nitrogen gas.

‘Creating a simulation of the procedure can help to identify which operating parameters can be optimised during the process so that it can be performed as expediently as possible,’ said Bray.

With that thought in mind, he developed a computer model to predict the transient temperature distribution through the different layers of composite materials in the aircraft wing inside the autoclave, a process that required him to model the effects of changes in temperature, pressure and airflow in the process. His software was later used as the front end for another programme that could automatically optimise the parameters involved in the production process.

Although Bray says he was challenged by those, and other assignments he was given during his summer placement work, he admits the projects he has been offered since he joined the company full-time have been even more intellectually stimulating.

Many have involved characterising the reliability of welded joints of components used in the commercial nuclear power industry.

To a casual observer, welding might seem a little old hat. After all, the technique - used to join two metal parts by heating workpieces and joining them with a pool of molten material - has been widely used in industry for years.

But the reality is a little different. Many companies, especially those in the nuclear industry, need to be able to accurately predict the likely lifetime of a joint in a system. The job involves creating a simulation of the entire welding process on a computer. That is no trivial task, yet that is exactly the task that Bray was assigned.

To solve the problem, Bray created a finite element analysis model of the specific components that were to be welded together, based on their geometry and the material that welds them.

Then, he modelled the intrinsic properties of the materials as they would behave during the welding process, using a combined isotropic and kinematic model in a finite element analysis program. ‘The model of the materials would have previously been fitted to cyclic test data at different temperatures close to the melting point of the material to ensure their accuracy,’ said Bray. Where such models were unavailable, he had to create them from the material test data.

He then created another computer model to simulate the heat delivered to the joint from the welding source, and thermally simulated the transient temperature distribution through the components during the welding process.

That thermal data was fed into a mechanical model that predicted how the materials would expand and contract the welding process, highlighting where residual stresses would be formed in the welded material.

‘The stress field created by the simulation could then be fed directly into a creep damage simulation that, together with other data such as the load and temperature that the joint would be subjected to in the field, can predict where and when such a crack is going to happen.’

Bray said his work on the welding project is typical of the simulation work that Frazer-Nash is involved with. While the company has access to the usual high-end FEA, CFD and thermal analysis tools, it is often the case that engineers like Bray need to write their own code as add-ons to those programs, or develop entire software from scratch if the job demands it to give them a capability that may not be available off the shelf.

But there is more to it than that.

‘Often, our customers do not have enough data that they can provide us to allow us to create a model of a particular system or process in the first instance,’ said Bray.

He added: ‘Ideally, we would like details about the properties of the materials that were used to manufacture a system. But if that detail does not exist, perhaps because of the age of a plant, then we have to make valued estimations before developing our model.’

However, Bray is quick to point out that conservative estimates are always used in such instances to ensure that the reliability or lifetime expectancy data created by the model always errs on the side of safety.

‘That’s a critical requirement for our customers in the nuclear power industry,’ said Bray.

Although it is clear that he loves the technical aspect of his job, Bray is also helping to manage other projects for which other engineers have the day-to-day responsibility.

At the moment, he has upped the ante in the simulation stakes by accepting a role that will enable him to model a complete manufacturing process for a particular part of nuclear power plant. While doing that, he will simultaneously manage a classified project for the defence industry.

Bray acknowledged that in part, his success at the company must be attributed to the encouragement that Frazer-Nash has given him to work on particularly demanding projects. ‘When I joined the company two years ago, I was given a very responsible role and that level of responsibility for managing and completing assignments has increased ever since,’ he said.