Today, getting products to market rapidly is essential in all sectors, not least the automotive, explains Bert Suffis, development & application sales manager – ARPRO, JSP. For products that provide protection, however, there is no getting away from physical testing to deliver real verification of performance and so satisfy increasingly stringent safety requirements.
The time and cost of virtual testing and prototype creation is similar whether the required component is complex or simple. But 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 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 increase.
Many designers are now eschewing physical testing until the last possible moment, preferring FEA (finite element analysis) and virtual testing. But 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, 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. As with any system, the results obtained are only ever as good as the information that has been input.
Developments in lightweight materials such as ARPRO, however, now give 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 application suitability.
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.
Prototypes for physical testing can also be rapidly created in lightweight materials using simple CNC equipment, so 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.
Regulations will invariably require a physical test to verify performance before a protective component or product is brought to market. 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.
ARPRO, JSP
