Characterization of Chip & Cut Behavior with an Instrumented Laboratory Device

Transcription

1 Characterization of Chip & Cut Behavior with an Instrumented Laboratory Device Radek Stoček 1,2, Martin Stěnička 1,2, Christopher G. Robertson 3, Reinhold Kipscholl 4 1 PRL Polymer Research Lab s.r.o., Nad Ovčírnou IV 3685, Zlín, Czech Republic 2 Centre of Polymer Systems, Tomas Bata University, Zlín, Czech Republic 3 Endurica LLC, 1219 West Main Cross St., Suite 201, Findlay, Ohio 45840, USA 4 Coesfeld GmbH, Tronjestraße 8, Dortmund, Germany

2 Presentation Outline Background Description of the instrument and testing methodology Results for model rubber compounds typical of tire tread applications Ongoing/future research Thermal imaging of the cyclic impact process with high-speed, infrared camera Simulations to give insights into complex rubber deformation fields and crack orientations during operation of the device Final Comments

3 Background: Chip & Cut (C&C) Damage to Tire Treads (a) and (b): TBR/heavy truck tires (c) OTR/construction vehicle tire (d) mud-terrain light truck tire

4 Description of the Instrument and Testing Methodology The Instrumented Chip & Cut Analyzer (ICCA ) is designed to analyze the C&C resistance of cured rubber specimens at room temperature The principle of measurement involves rotating the round rubber sample at a selected speed and striking the sample with a stainless steel impactor at a specified frequency and contact time The ICCA is manufactured by Coesfeld GmbH, Dortmund Germany Rubber Specimen Geometry 55 mm outer diameter 13 mm thickness

5 Description of the Instrument and Testing Methodology The impact is produced using a pneumatic cylinder, where the following can all be separately controlled: Normal force Impact frequency Contact (sliding) time with the rubber surface Normal force, shear force, and indentation depth are all measured as a function of time for each impact impactor geometry F S sample actuator F N 2-dimensional loading cell impactor w

6 Normal force Description of the Instrument and Testing Methodology top view Time side view

7 Shear Force F S [N] Method of Analysis Evaluation: C&C Propensity, P 250 One key characterization factor that is evaluated from the multi-channel data acquisition is the C&C propensity, P Cycles n [-]

8 Method of Analysis Evaluation: C&C Propensity, P

9 Shear Force F F S S [N] Method of Analysis Evaluation: C&C Propensity, P 250 One key characterization factor that is evaluated from the multi-channel data acquisition is the C&C propensity, P The parameter P is determined from integrating the fluctuations in shear force related to roughness of the damaged surface over a number of impacted cycles A lower value of P is associated with greater C&C resistance Cycles n [-]

10 Parameter P Shear Force F S [N] Shear Force F S [N] Method of Analysis Evaluation: C&C Propensity, P Cycles n [-] Cycles n [-] Cycles n [-]

11 Evaluation Study Test Conditions for C&C: Rotation speed = 140 rpm Impact normal force = 150 N Impact frequency = 5 Hz Contact time = 35 ms

12 Evaluation Study Tensile Data Hardness Shore A and DIN Abrasion Volume Loss

13 Evaluation Study n = NR Impactor direction n = SBR n = 300 BR 13

14 Evaluation Study NR n = SBR Impactor direction n = BR n = 300

15 CC Propensity, P C&C Propensity [N/cycle] Evaluation Study NR SBR BR Number of Cycles, n Number of Cycles n [-]

16 Ongoing Research: Thermal Imaging - High-Speed IR Camera First Few Impacts After 30 Impacts Impact can generate heat due to mechanical energy dissipation in the rubber (hysteresis)

17 Endurica IMPACCT Investigative Modeling Package for Analysis of Chip and Cut Test ENDURICA finite element model of the Coesfeld ICCA with guidelines for its effective use will be offered as an option with the purchase of the testing equipment View the stress and strain response across the specimen cross-section during impact testing Guide selection of ICCA testing conditions to match typical deformations in desired rubber application Tire treads Rubberized tracks Conveyor belts Investigate testing geometry effects Impactor tip shape Diameter of specimen holder

18 Ongoing Research: FEA Simulation Maximum Strain = NR SBR BR

19 Ongoing Research: Prediction of Lifetime SBR Crack precursor size = 50 m Simulation vs. Real Behavior

20 Ongoing Research: Prediction of Lifetime

21 Conclusion The ICCA is a new test device for the rubber laboratories that controls and records applied loads and displacements during cyclic impact to mimic and quantify the C&C damage experienced by tire tread compounds on rough terrain Development of shear force fluctuations related to surface roughness with number of impact cycles (slope of P vs. n) can clearly differentiate rubber compounds for their resistance to C&C damage side view

22 Acknowledgement The Endurica Team Dr. Will Mars Founder & President Linda Mars Office Manager Joe Suter Business Manager Mark Bauman Engineering Analyst Jesse Suter Development Engineer Dr. Chris Robertson Sales Director Pauline Glaza Marketing Communications (contract) Margaret Bauman Web Designer (contract)

23 Thank You for your kind attention!