An automated testing method to investigate the fatigue behaviour of strongly elastic materials has been developed under the DIMECC HYBRIDS program. The testing procedure enables the automated detection of the crack growth under fatigue loading for materials like rubber. Utilization digital image processing technology and servo hydraulic loading frame the resistance of materials against fatigue loading can be defined in a precise and traceable manner. By using an automated testing routine a variety of materials can be effectively tested in the required design cycle.
Modern high-tech industrial products are mostly made by combining and joining various materials with unique properties with the aim of improving the overall capacity and performance of the products. When more complex systems of materials are applied in the same product, more knowledge of systems components and more design parameters are required. One of the key questions of the hybrid structures is related to the overall durability at both the system and component level. I order to achieve a good level of reliability proper testing and design methodology is needed.
Elastomers have a strong tendency for viscoelastic behaviour and this poses challenges for dynamical testing of this class of materials. In industrial applications the substrate, or base material, undergoes strong cyclic loading and the resistance of the system against fatigue becomes noticeable important. To understand how new materials and material combinations behave in various loading conditions, a comprehensive test series needs to be accomplished in a short time.
The developed test procedure can be applied for elastic materials found in numerous products. Although the test is already applied especially for rubber material, the work will continue toward more generalized form of the developed method. Typically experimental testing of cyclic loadings is very time consuming and savings due to robust and automated test procedures will remarkably shorten the design time, and thus enable the development of totally new design candidates and speed up the overall design process.
Kari Dufva, Mikkeli University of Applied Sciences
Nokian Tyres, Mikkeli University of Applied Sciences