Simulation using BikeSim to analyse vibration of racing motorcycles during cornering (left) and simulation of a motocross jump using BikeSim (right) ➤ At the high speeds and with a very high
angle of lean during cornering, as described in the paper, Watanabe explained that this is effectively a different system from that of a motorbike under normal conditions. Tis is largely because the suspension effect is reduced as they are not directly over the wheel due because of the very steep cornering angle. Dr Michael Sayers, CEO and founder
of Mechanical Simulation, stated that understanding these complex problems would not be possible without simulation tools such
THE USE OF
SIMULATION ENABLED THE RESEARCHERS TO IDENTIFY AND UNDERSTAND THIS VIBRATION MODE
as BikeSim. Sayers said: ‘Without simulation this kind of testing is just not feasible because of the difficulties in recreating these conditions with physical testing. While normal physical testing could not
provide a comprehensive answer to describe this phenomenon, the simulation environment provided by Mechanical Simulation – through its BikeSim soſtware – was used to identify the existence of a vibration mode that aligns with the experience of the riders using these bikes under these cornering conditions. Watanabe explained that further research
using BikeSim tools for linear analysis showed that all motorcycles have the potential for chatter vibration as well as weave and wobble motions. However, the chatter is usually stable and doesn’t resonate under normal riding conditions; it mainly appears under race conditions when the chassis structure is not stiff enough. Te use of simulation, in this case, enabled
36 SCIENTIFIC COMPUTING WORLD
the researchers to identify and understand this vibration mode which was very hard to test accurately without simulation because of the very steep angles that these racing motorcycles would achieve while cornering at the very edge of the limits of the tyres’ grip.
Limits to physical testing Another aspect to consider is that while the physical testing could be used to identify the problem, it cannot be used to elucidate the root causes fully, and thus cannot always be used as a tool to give the researchers and engineers knowlege about how to fix the problem. Tis is an area where simulation can perform
much more efficiently than physical testing alone, as a sensor does not need to be attached to every critical part as physical testing would require. In a simulation environment, you can collect much more information, which can then be used to influence future design changes. ‘Te physical testing tells you the “what”
but not necessarily the “why”,’ said Dodd. ‘Understanding the “what” and the “why”, means you can learn about your design and you can make progress. You don’t have to do the same thing next time you design it; you add to your knowledge and make things better the next time around.’ One way to increase the knowledge
generation process is to couple different simulation disciplines into a single environment. Tis can be used to provide a more comprehensive solution to a particular problem, as changing one system or component can have a knock-on effect on another. Dodd explained that recognising that
this ability to generate more knowledge from simulation is seen as critical to driving automotive design for MSC users – not only because it provides more information to users but also because it can increase the fidelity of the simulation response. Dodd
said: ‘Recognising that, and working with our customers in the past, we have provided the capability to couple these tools. We can run a co-simulation, which is where two of these tools talk to each other as they are doing the analysis, and they can swap information.’ One example that MSC soſtware supplied
to illustrate the use of MSC soſtware in the motorcycle industry, was a project that they worked on in partnership with Mahindra Motorcycles, an India-based motorcycle manufacturer that wanted to improve the design. In the past, the design of new two-wheeler
models at Mahindra was based on building prototypes and driving them on a test track. Te obvious limitations of this approach were that prototypes took an average of five weeks to build, and had to be run for about two weeks to evaluate component durability – leading to a long development cycle and the extra costs associated with the construction and testing of these prototypes.
24-hour testing A major improvement to this system came from the development of test rigs, which were introduced to recreate the conditions of the test track, using automated equipment that eliminated the need for a driver and could be operated 24 hours a day. Although this approach saved time, costly vehicle prototypes were still required for each major design change. Te final solution was to use MSC soſtware
– specifically ADAMS for its multi-body dynamics capabilities – to simulate this vehicle and the test track. In this way, the process can be largely automated and used to optimise the process, as many different design iterations could be tested in a much shorter period of time and at a significantly reduced cost. ADAMS is an acronym that stands for Automated Dynamic Analysis of Mechanical
@scwmagazine l
www.scientific-computing.com
Mechanical Simulation Corporation
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
