Dynamic testing can help address key industry issues

Dutch group VMI recently introduced advances to its LAT100 dynamic testing system, which employs mathematical functions that allow the software to alter test parameters of vehicle tires.

Characteristics such as load, speed, and slip angle can now be tested simultaneously with the travelling distance – previously, the only parameter that could be varied with test time. 

Here, Dr. Ir. Marzieh Salehi, process specialist, R&D apexing and compound testing, at VMI explains the background to the development and its contribution to industry efforts to address environmental issues around tire wear:

ERJ: Why is dynamic testing of tire treads important right now?

MS: In short, dynamic testing is a lot faster, and more accurate with limitless choices of test design. This can open a new horizon in tire testing compared to conventional measurements.

The substantially reduced testing time provides a steadier state in the rubber contact area. Thus, the accuracy is enhanced by omitting the inherent noise factors of long-term experiments due to the travelled distance of rubber on the track. Overall, this can provide up to eight times more productivity and testing capacity in LAT100 testing per year.

ERJ: Which type of tires is this testing applied to?

MS: Almost all types of tires. You can define dynamic functions for any test procedure, surface condition (dry, wet, ice), and test track type. For agricultural and OTR tires, there may be some limitations due to different mechanisms involved in rubber abrasion and friction based on the type of surface being used in the test configuration.

ERJ: What are the main limitations of conventional equipment used for these tests?

MS: Longer testing time and lower degree of freedom in the test design in comparison to dynamic testing. Conventional testing with LAT100 equipment is widely being used with valid measurements output because it is still remarkably cheaper with reduced testing time compared to real tire testing on the road. Dynamic testing is more advanced with a higher degree of freedom for flexible test designs which is similar to what actually happens on the road.

ERJ: Is VMI’s new testing feature already being used in the tire industry and, if so, any more details?

MS: At present, there are four clients using the beta version of LAT100 dynamic testing. This new dynamic future is not officially released yet. Basically, we proved the idea of dynamic testing in strong correlation with the tire data.

Currently, the machine software supports a variety of designs of experiments. By finalising the data analysis software, documentation, and technical manuals, VMI will officially release the dynamic [offering] by the end of this year.

ERJ: What are the next steps in the development programme?

MS: The next interesting step for the development of LAT100 is to implement dynamic testing for abrasion resistance measurements to benefit tire wear – the most expensive and time-consuming test in the tire industry. VMI already has a good basis of ISO 23233:2016 for the determination of resistance to abrasion using a driven, vertical abrasive disc.

It is of high value to enhance this ISO standard, especially with the upcoming demanding regulation of tire energy labelling and the emergence of important issues around tire microplastics, and tread road wear particles (TRWP).

ERJ: Any other points?

MS: Yes. The ‘care for the environment’ tire labelling is a tailored measure to benefit and reduce TRWP emissions, a growing issue which is turning into a newly emerged problem.

It is time to put laboratory measurements of rubber abrasion as a priority to minimise the need for tire wear measurements related to rubber material development.

By far, rubber abrasion is one of the most difficult topics known in elastomer science and engineering because it involves the friction and interaction between two complex constructs: the tire and the road track.

Generation of TRWP is inherently embedded in the rubber abrasion phenomenon. There is enormous research being done in rubber abrasion and tire wear and yet, more investigations are required to be pursued with a rather newer vision of TRWP generation.

This topic demands special attention, as described by ETRMA: a holistic and multi-stakeholder approach that involves different organisations, associations, and tire companies to offer a solution.