Written by Bert Suffis, Development & Application Sales Manager – ARPRO, JSP
In all sectors, not least automotive, the need to get products to market rapidly is key. However, for products which provide physical protection, there is no getting away from physical testing to deliver real verification of performance and so satisfy increasingly stringent safety requirements.
Whether the required component is complex or simple in design, the time and cost of virtual testing and prototype creation is actually remarkably similar. Unfortunately, for many materials, creating a physical prototype which can be guaranteed to offer the same performance under test conditions that the final product will deliver in real life scenarios remains a difficult and in many cases insurmountable challenge. Many of the materials commonly used for protective applications do not lend themselves readily to the creation of prototypes due to the expense of tooling required and the fact that a small batch of prototypes may differ significantly from the final product in terms of their physical characteristics. Meanwhile, the cost of making adjustments once a physical prototype has been tested can rapidly stack up, especially if more than one set of adjustments is needed. Consequently many designers are now eschewing physical testing until the last possible moment, preferring to invest substantial engineering time and resource in FEA (finite element analysis) and virtual testing in a bid to get as close as possible to the finished product at prototype stage.
But even with the technological advances in FEA and other software, just how reliable can these results really be? FEA can only be trusted once good correlation has been proven, which takes multiple cases of parallel virtual and physical testing, as well as material characterisations and eventually FEA material model developments. Furthermore, no matter how detailed the virtual test, the fact remains that it is still virtual, with no guarantee that the results will be replicated in a real crash scenario, especially in the case of new and previously untested materials. And as with any system, the results obtained are only ever as good as the information inputted.
However, developments in lightweight materials such as ARPRO now allow designers the option of cutting the time and cost of FEA while enabling easy and reliable physical crash tests.
These materials have been used in key safety applications for a number of years meaning there is significant data available on material performance under a range of different conditions and subject to a variety of impactors in terms of size, shape and velocity. Not only does this data allow designers to create virtual designs for FEA which are likely to be more accurate and closer to meeting safety requirements first time around, but the ability to work closely with the manufacturer of the lightweight product allows access to a wealth of knowledge about what the material is capable of and its likely suitability for a particular application.
Perhaps most importantly, the physical performance of the prototype can be guaranteed to replicate that of the finished product as exactly the same material is being used. In simple terms, it is as close to a real life scenario as possible.
Meanwhile, given that prototypes for physical testing can be rapidly created in lightweight materials from even a basic design brief using simple CNC equipment in a matter of days, there is no need for investment in extensive tooling. Even after the test, because of the accuracy of the FEA based on the enhanced data available, it is rare for more than one set of design amendments to be needed. What is generally the case with lightweight materials is that the first real test equates to the third optimisation loop of virtual testing using alternative materials.
Ultimately, regulations will invariably require a physical test to verify performance before a protective component or product is brought to market. It simply cannot be avoided, so the way forward is surely to reduce the cost and time at this stage of the process through using, wherever possible, proven materials which allow for the most accurate FEA and simple, rapid creation of physical prototypes.