EUROPEAN COMMISSION SEVENTH FRAMEWORK PROGRAMME THEME SME Research for benefits of SME Association

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1 EUROPEAN COMMISSION SEVENTH FRAMEWORK PROGRAMME THEME SME Research for benefits of SME Association GA No Classification of retreaded truck tyres in order to comply with future environmental performance and safety requirements Deliverable No. RETYRE D5.1 - revised Deliverable Title Validate tool for predicting retreaded tyre performance Dissemination level Written By David Gallegos (IDIADA), Jesús Gallego (IDIADA), Alba Fornells (IDIADA), 23/02/2015 Anna Molinari (KCL), Richard O Connell Checked by Steering Committee and Ruud Spuijbroek (KCL), WP leader 10/03/2015 Approved by Ruud Spuijbroek (KCL) Project Coordinator 13/03/2015 Issue date 13/03/2015 1/9

2 Executive summary Based on the deliverables from WP1, WP2, and WP3, a mathematical model is set up which can be used to estimate the performance of a retreaded tyre (Deliverable D4.2). Next, a prototype of a tool has been developed (Deliverable D4.3). This alpha version of the software tool needs to be validated by feedback from the users and randomly selected tyres. 2/9

3 Contents 1 Introduction Document Purpose Background of the deliverable Overall Description of validation procedure Extra tests Feedback from retreaders and experts Cross check Results Analysis of the Comparison Outcome/Lesson learnt Conclusions Acknowledgment /9

4 1 Introduction 1.1 Document Purpose This document describes the steps undertaken for the validation of the predictive tool. It was planned, according to the DoW, to proceed with the validation following two parallel/complementary ways: A. Via feedback from the retreaders on the usability and user friendliness of the software tool. This may lead to modification and improvement of the software. B. Via tests of randomly selected retreaded tyres according to UN-ECE Regulation 117 The software tool is validated if the results of the tests of the randomly-selected retreaded tyres and in alignment with the predicted retreaded tyre performance. The validated tool is the basis for enabling type homologation of retreaded tyres according to the UN-ECE Regulation Background of the deliverable The project accumulated in the first period (till the end of the second one) a delay of close to 4 months. In order to recover the delay, as suggested by the Commission during the second Review Meeting (18 th February 2014), the following actions have been undertaken: - Front-load work in WPs 4 and 5 to ensure that the developed code can be ready and checked before end of project duration - Optimisation of the selection and number of additional tests for validation - Usage of existing database to provide extra necessary information for the preparation of the tool This deliverable reports on the outcome of those actions. After the first submission at the end of the project an update has been requested in order to include the results from the cross-check: as mentioned in this report a validation matrix has been prepared and field tests have been performed at IDIADA, at the same time some virtual tests have been done using the available version of the software tool. This revised deliverable includes the cross-check results. 4/9

5 2 Overall Description of validation procedure 2.1 Extra tests The retreaders participating in WP5 (Banden Plan Europe, Insa Turbo, Carling and Bandvulc) prepared 12 tyres (divided in 3 sets, 4 tyres for each set in order to have a good statistic and reproducibility) for the validation phase. The dimensions selected for the tyres are based on market representation and availability. Three dimension have been chosen: - 385/65 R /70 R /70 R19.5 Most of the other input parameters were different for the different retreaders: - Original manufacturer - Original design - Retreading process (7 SETs were processed with HOT-cure method and 5 with COLD-cure method) - Tread compound - Retread pattern The total 48 tyres have been tested for Rolling Resistance, Noise Emission and Wet Grip at IDIADA according to the ISO standards. Because of the public dissemination level of this deliverable the results will not be presented here (but they will be available for review in the Periodic Report). The same input parameters used for the validation tests by IDIADA has been inserted in the alpha version of the software tool in order to check if the results for the selected retreaded tyres are in line with the predicted retreaded tyre performances. 2.2 Feedback from retreaders and experts In parallel with the validation tests at IDIADA, VORtech prepared the first online tool for the estimation of tyre performances. As reported in the deliverables submitted for WP4 the software tool has been prepared based on the tests results for WP1-3 and the BAC database for new tyre performances available at VACO. The first version have been distributed to the Steering Committee for a preliminary check. Different inputs on the necessary inputs parameters have been provided an implemented in the system. The Steering Committee agreed on the general presentation, its look & feel and the user-friendliness. At the time of the preparation of this document two suggestions are not yet implemented (but work is in progress): - To at least be able to comply with 1222/2009 the possibility of printing the values resulting from the label estimation: we have been using the tyre labelling figures and ranges (classes) defined for new tyres - Possibility of selecting (for the retreading specifications) among few different possible (max 7) tread patters: the noise emission results are currently mainly based on the data available in the BAC system for new tyres, but the original pattern is different. However, to reduce too much deviation further steps are in progress. (To be published in the Periodic Report) 5/9

6 3 Cross check Results Below are reported the tests results and the results obtained by the simulation. Validation using the applied tread pattern as a reference Actual values from test Calculated values from tool Tyre Size Retreader Pattern Applied Buffed Radius % Natural Rubber RR value Noise Wet Grip RR value Noise Wet Grip 385/65R22.5 Insa XTE D 72,6 B D 69 B 385/65R22.5 BPE HN E 73,9 B C 76 C 385/65R22.5 Carling Gdyr LHT D 73,8 B C 72 C 385/65R22.5 Bandvulc XZA C 74,2 C E 69 B Actual values from test Calculated values from tool Tyre Size Retreader Pattern Applied Buffed Radius % Natural Rubber RR value Noise Wet Grip RR value Noise Wet Grip 315/70R22.5 Insa VT E 73,4 A E 72 C 315/70R22.5 BPE TDM F 74,3 B D 72 C 315/70R22.5 Carling RHD E 77,5 B D 75 C 315/70R22.5 Bandvulc BD D 78,1 C F 75 C Actual values from test Calculated values from tool Tyre Size Retreader Pattern Applied Buffed Radius % Natural Rubber RR value Noise Wet Grip RR value Noise Wet Grip 285/ Insa TDE F 74,9 C E 73 C 285/ BPE BDR-AS F 76,9 C F 74 C 285/ Carling Marangoni RD F 76,2 C E 74 C 285/ Bandvulc BDE C 75,4 D E 73 C 6/9

7 3.1.2 Analysis of the Comparison We have developed a working tool and through our tests can now establish which input data are important in producing an effective labelling system. The established important data is, tread pattern (drive, steer or trailer,) tread depth (including undertread) plus a measure of the resilience of the compound (Tan δ). The Alpha version does not contain a method of entering these important data, however the tool is well equipped to record the base information for each casing being processed which could prove useful in the future if there are significant variations between manufacturers casings in the future. The Beta version of tool must now be developed to incorporate the above data, when we will see a marked improvement in the information produced. It was not initially appreciated what a huge impact the resilience of the tread compound has on noise, wet grip and rolling resistance Outcome/Lesson learnt The manufacturing information of the tyres prepared for WP5 have been used as input parameters for the alpha version of the software tool and the simulation results have been compared with the real results. The idea is first to test how the alpha version of the software tool can predict the tyre performances (level of accuracy) and, in a second stage the values obtained by the validation phase will be used, if necessary, as extra data for the updated version of the software. From the cross check it appeared that: 1. More retread manufacturers should be in the selection for the retreading specification specifications: currently we have the two main manufacturers (Kraiburg and Bandag) but European retreaders use also other suppliers, such as Marangoni, Mezclas del Caucho, Vipal, Goodyear NextTread, Ringtread, etc.). As already communicated the compound can differ importantly on the subject of both Rolling Resistance and Wet Grip. It is therefore necessary to adjust the algorithm towards an improved understanding of the relationship between the relevant parameters and its Tan Delta properties. The choices yet in the tool are too general and abstract to define the result to an acceptable value. Usually minor the tread pattern and related tyre performance for using minor manufacturers are similar to one Kraiburg or Bandag tread, but nevertheless categories should be defined in order for each retreader to insert the available pattern. 2. Recent updates in the BAC data base for new tyres should be taken into consideration in the model (few tyres performances cannot be predicted) It is therefore necessary to disclose the database for both actual market presence and archives. 3. Information on the percentage of natural rubber in the tread composition is requested as retreading parameters, this is not always known by the retreaders and during the tests for WP2 and Wp3 it appeared clear than another more general and also most important parameter still needs to be investigated: tan delta related to the physical properties of the rubber. This point is currently under evaluation. 7/9

8 4 Conclusions General conclusions for this document are: 1. In general the estimation are in line with the expectations. 2. This is due to the use of data for new tyres, the results from WP5 tests should also be taken into consideration in the model. 3. With tan delta results and the different categories for tread patterns the results should be more realistic (we trust this is true but we still need the proof) 4. The tool is considered a very good start point but cannot be 100% validated 8/9

9 5 Acknowledgment This project is co-funded by the 7th FP (Seventh Framework Programme) of the EC - European Commission DG Research Disclaimer The FP7 project has been made possible by a financial contribution by the European Commission under Framework Programme 7. The ation as provided reflects only the author s view. Every effort has been made to ensure complete and accurate information concerning this document. However, the author(s) and members of the consortium cannot be held legally responsible for any mistake in printing or faulty instructions. The authors and consortium members retrieve the right not to be responsible for the topicality, correctness, completeness or quality of the information provided. Liability claims regarding damage caused by the use of any information provided, including any kind of information that is incomplete or incorrect, will therefore be rejected. The information contained on this website is based on author s experience and on information received from the project partners. 9/9