applications
Systems. ‘Multi-body simulation, as the name suggests is taking multiple parts together’ stated Dodd. He went on to clarify that an example of this is a motorcycle chain, which is made up of many links, all joined together by a pin. ‘Now that is a very simple example, but it is a good case of a system with multiple bodies that these individual links interact with to describe the behaviour of the overall system, in this instance, the chain’ said Dodd. Tis process can be extended to all kinds of
components such as gearboxes, engines, the crankshaſt, the connecting rod or the pistons and how they interact with the stiffness of the cylinder block. Dodd said: ‘All of these components are moving relative to one another; all of these components are generating forces, and the kinds of motions can be rotational, translational. Sometimes this can be at relatively high frequencies – a car engine, for example, can typically spin at 6,000 to 8,000, RPM but a motorbike can be up to 16,000 or 17,000 RPM.’ Multi-body dynamics enables users to break
down the complex systems made up of multiple moving bodies so that the interactions can be fully understood. Tis gives engineers a much better understanding of the forces involved, and this can be translated into stresses and strain on components, which can be used to improve design performance or to look at a product’s fatigue in a certain set of conditions. While this process did not involve any
simulation – merely building a test rig that enabled the researchers to move testing from the road into the lab – the second step involved creating an analytical model that could replicate the actions of the test rig, so that the process could be moved into a simulation environment,
reducing the need for physical testing other than to validate the analytical model itself. Dodd said: ‘Tese tests allow the team to
build up confidence in the predictive nature of ADAMS and FEA, so that they can then use this virtual rig for testing out possible designs.’
Simulation on the rise Tis process highlights a trend in the automotive industry where many companies want to move as much of the design and engineering to computer-based simulation. Tis was a sentiment shared by Altair, as
Michael Johnson, senior application engineer at Altair explains: ‘A trend in motorcycles, and for the wider automotive community, is moving validation of components from the road to the lab, and now to the screen – which provides significant cost and time savings.’ Another trend highlighted earlier is the
desire of many automotive companies to build up as much knowledge as possible. Tis can be passed through the company to other teams and individuals – so that engineers do not have to re-invent the wheel every time they start a new design. By coupling simulation tools, and by
exploring and solving challenges previously unsolved through purely physical testing, simulation engineers generate a huge amount of data. Te next challenge is to understand how to utilise this data fully to generate knowledge for the organisation that puts all the time and effort into these simulations. Altair provides a comprehensive soſtware
portfolio – Altair Hyperworks – which enables users to take a product from the initial design stages through simulation to the final product, including structural analysis, durability,
Noise analysis of a motorcycle engine using ACTRAN
safety, NVH, CFD, aerodynamics, multibody simulation (MBS) , vehicle dynamics, optimisation, materials analysis, engine/ powertrain, and control systems and model- based development. By offering all of these solutions, and those
of the Altair Partner Alliance – of which Mechanical Simulation is a member – means that users can couple simulations as well as helping users to move data quickly from one stage of the vehicle design process as it is needed. Tis is also true of MSc soſtware – as
Dodd explains – by using a soſtware portfolio allowing users to concentrate on the engineering rather than moving data and selecting the appropriate file formats: ‘Using an analytical tool like ADAMS gives you the ability to post-process the results. You can start looking at loads, stresses and strains, different characteristics around the whole vehicle to try and understand why something happened. It is very difficult in a physical test, unless you happen to have put testing instruments in the right area and you can’t instrument them all.’ ‘In theory, you can retrieve information
from any part of the model when it is on the computer – but you can only understand how the part performs under physical testing if you have got some kind of instrumentation in the right spot.’ Using simulation allows engineers to switch
their interrogation as soon as some new piece of information indicates a problem could be solved elsewhere – rather than having to re-tool, create new prototypes and design new experiments, as is the case with physical testing. Dodd said: ‘It gives the ability to learn because
you can interrogate the model to find out why something happened. If you came up with a poor design for whatever reason, then you can understand why it did not work and then you can make sure you don’t do that again.’ ‘It’s not enough to say that as an individual
BikeSim graphical user interface
www.scientific-computing.com l @scwmagazine
will not make that mistake again – we need to pass that information on as a company to make sure that the enterprise does not make that same mistake again,’ concluded Dodd. l
FEBRUARY/MARCH 2016 37
Mechanical Simulation Corporation
MSC software
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