Component design How to predict the service life of plastics more quickly

Editor: MA Alexander Stark

Germany — If the development of plastic components is to be accelerated, service life tests must also be shortened. For complex application scenarios, the Fraunhofer LBF is now coupling customised testing methods with modelling software for life prediction.

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Laboratory weathering of plastic components is just one test of many. Together with industrial partners, the Darmstadt researchers adapt it to the respective problem.
Laboratory weathering of plastic components is just one test of many. Together with industrial partners, the Darmstadt researchers adapt it to the respective problem.
(Source: Fraunhofer LBF / Ursula Raapke)

Plastics are under stress from their environment: changing temperatures, solar radiation, humidity, chemical substances and mechanical loads all affect them and change the material properties. In order to minimise the risks when using new materials or when operating conditions change, reliable statements on service life are required. In addition to test methods that detect damage at an early stage, this requires suitable ageing and failure models as well as application-relevant damage criteria. In order to accelerate material and component development, it is also useful to shorten the duration of test cycles, climate storage or laboratory weathering.

Coupling ageing experiments and modelling

Time-consuming and costly tests are required for material and product development and to reduce the probability of failure in use. There are limits to accelerating such tests through increased temperatures, ambient humidity, irradiance or shorter test cycles. It is even more difficult to predict ageing and failure for new operating cycles or for use under changed environmental conditions.

In the department for plastics at the Fraunhofer LBF, interdisciplinary teams are working closely together to better understand the ageing processes and failure mechanisms of plastics and to improve the associated material and service life models. The aim is to optimise test methods and software tools for life prediction for complex application scenarios. By coupling ageing experiments and modelling, the Fraunhofer LBF scientists can better estimate service life and risk of failure for given use cases. By superposing successive temperature, humidity, irradiation and mechanical loads, they can simulate almost any scenario. Time-resolved measurement data for various operating conditions, weather data or hypothetical application scenarios serve as input variables.

Results are directly incorporated into component design

The Fraunhofer LBF has a toolbox available for this purpose, consisting of climate storage and weathering, a variety of measurement and test methods, a wide range of chemical analysis and adaptable ageing and service life models. The approach can be directly coupled with component design using FE methods. Together with industrial partners, the Darmstadt researchers adapt these to the respective problem and accompany the transfer into existing processes and existing infrastructure. The results are application-specific test standards, shorter development times and a reduced risk of failure in later use. Target groups are manufacturers and users of plastic components and parts as well as polymer-based coating materials in almost all economic sectors.

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