Gary Carter reports on how CAD integrated software was used to push forward one of the latest innovations in washing machines.

British entrepreneur James Dyson took the humble act of vacuuming, complete with clogged bags, fading suction and dowdy designs, and turned it upside down. Or rather, round and round. Dyson's patented dual cyclone technology which promises no loss of suction, plus innovative and attractive design, was launched in 1993. The company is the UK market leader and has a worldwide turnover of £300m.
The company has now turned its attention to a new area in the home, launching an innovative washing machine, the Contrarotator. It is the only washing machine on the market with two-drums rotating in opposite directions to give the cleanest wash results, with the largest load, in the fastest time. Launched in January2001, it has already achieved a significant share of the £500+ market and is first, second and third in the £900 plus category.
"James Dyson built over 5000 prototypes of the original dual cyclone," explains Stefan Kukula, head of the analytical services group at Dyson. "With products such as a washing machine it's more difficult and costly to make that number of prototypes, so we made much more use of analytical techniques."
Key to this effort was DesignSpace - the CAD integrated software from ANSYS. "For example, the CR-01 uses a single high performance sports car bearing to support the drums instead of two lower grade bearings," explains Kukula. "DesignSpace was used to check the supporting 'spider' could take the load and help optimise its design."
"In many ways it is a natural extension of physical prototyping. With virtual prototyping provided by finite element analysis (FEA) complementing our test program we could run through hundreds of designs before settling on suitable candidates to check physically."
FEA allows design engineers to construct computerised models of linear, planar and solid engineering structures and components. The concept of the method is that a structure or component is optimised as an interconnected assembly of elements. These elements are designed to model specific engineering phenomena and to respond under loading conditions accordingly.
"We also used FEA to help design fatigue test rigs, ensuring that the stresses produced mirrored those we expected the components to see in service. After all, there's no point in doing a test if it isn't helping you design a better product."
Dyson places great emphasis on the design of products, and is keen not to stifle creativity. "DesignSpace is the ideal tool for this. We can allow trained engineers to do preliminary analyses and checks locally, straight from CAD models on our Unigraphics system, before later stage designs, or trickier problems, are qualified by more specialist software, such as ANSYS/MultiPhysics, if required." This method was used on Dyson's latest cleaner, the DC07, which extends the original dual cyclone concept to eight cyclones to produce the Root8, the most powerful upright cleaner on the market. "We used DesignSpace to check the structural integrity of key components as the product was being designed, reducing the number of surprises we came across during user trials."
The mix of dispersed design level and concentrated specialist tools offers great advantages for a company such as Dyson, and Kukula is keen to stress the opportunities. "The capability to tie in the different powerful analysis physics available in ANSYS/Multiphysics with the design friendly front end of DesignSpace has been very exciting, and we're looking forward to using the new parametric abilities of DesignSpace 6 to exploit whole new areas."
DesignSpace 6.0 features numerous capability additions including parametric simulation, thin sheet metal capability, advanced non-linear contact, fatigue and new meshing controls. Of these, parametric simulation, through bi-directional computer-aided design (CAD) associativity, is the most innovative feature and is unique to ANSYS.

ENQUIRY No 61

Gary Carter is with ANSYS Europe, Riseley, UK. www.ansys.com. For more information on Dyson, visit www.dyson.com