CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Deliverables
Testing methods were developed for characterisation of rubber materials including elasticity, softening/recovery and fatigue performance. They are mainly focused on mechanical properties determination and feeding constitutive and life prediction models for elastomers. They account for dependency of material properties on several functional aspects like temperature, ageing and strain rate.
The effect on physical properties related to microstructure from processing like state-of-mix, molecular-orientation and memory-interfaces, was determined and their relative importance established. Fatigue testing of various materials, accounting for processing and thermal effects, has shown the important aspects of material response determining component life.
A working procedure for F.E. characterization of rubber materials as well as its limitations were established focused on determination of appropriate numerical models for simulating rubber-components. Material models developed to represent fatigue properties can be used with appropriate functional analysis to predict component life. Sometimes, a fracture mechanics approach is required. In others, a local strain based approach is sufficient.
This know-how can be exploited by rubber-component-manufacturers and polymer-processors to improve manufacturing processes. Ability to exploit these methods depends on companies being aware of the results of the project and the potential application in their field. For this, there should be targeted dissemination of the relevant information to companies.
Mould-filling simulation is potentially very useful to rubber-component-manufacturers, reducing tooling costs, and increasing production efficiency by reducing waste of material, time and energy. However, there is little use of filling-simulation by rubber industry due to their experience of poor predictions and the large number of measurements of material properties that have to be made.
A methodology is developed on the basis of commercial codes for rubbers processing simulation and intends to be a useful tool for design or improvement of manufacturing processes with rubber. It includes understanding of mathematical description of models that account for special rheological properties and testing methods for assessment of necessary parameters. During the project the sources of many of the poor predictions were identified and ways of avoiding them established. Also it is determined how to minimise the number of material-parameter measurements.
In addition to the outputs of filling-simulation, a stress relaxation model was developed which, together with existing FE-software, can predict skin orientation in rubber-parts. This is important because it causes distortion and may also significantly affect fatigue life. All these models are validated against experimental data provided for two materials.
We can offer a service of mould filling simulation for elastomeric components, which is of great value to the rubber industry.
Planes of weakness may occur in rubber products where material interfaces come together during processing. A test has been developed to diagnose if such weaknesses are present in a moulded rubber product. The test is a gas decompression (GD) test.
Gas is dissolved into the rubber under elevated pressure and temperature conditions for a period of time. When the pressure is released, the gas forms bubbles that may grow and cause fracture at a weak interface. A number of variables are available to adjust the severity of the test (type of gas, pressure, temperature, time, decompression rate).
By adjusting the severity of the test conditions, a test can be performed that only causes damage when a weak interface is present. The test was developed using test pieces with controlled and measurable interface strengths. The test has been successfully applied to a rubber pad from a tracked vehicle to show the effect of different processing methods. The methodology can be extended to consider weak bonds in rubber-to-metal bonded components and other interfaces such as with reinforcements in tyres. The methodology may therefore be applied to a range of industrial rubber products where structural integrity is important: tyres, mounts, bushes, seals etc.
It is also applicable to components that are required to operate under high pressure/high temperature conditions e.g. seals and hoses used in the oil and gas industry. The methodology is particularly relevant to rubber materials that possess low tack, where the risk of weak interface formation is greater i.e. materials used for high temperature applications.
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