When there is rolling or sliding contact of a rubber surface over a second hard surface of sufficient roughness, localized cutting and damage of the rubber surface sometimes becomes a problem. It occurs in off-road tires operating on stony surfaces, for example, and it can severely limit the useful life of a tire. In order to study this “cutting and chipping” failure mode, Endurica last month acquired a new testing instrument: the Coesfeld Instrumented Chip & Cut Analyser (or ICCA). It has been set up at partner lab ACE Laboratories, commissioned, and it is now ready for running tests.
The ICCA test uses a solid rubber wheel specimen. These are molded from uncured rubber compound supplied by the client. Alternatively, the mold can be rented if the client prefers to produce their own specimens. The ICCA test offers direct control and measurement of the following key parameters
- Wheel revolution speed
- Overall impact period, tP
- Peak impact force, FD
- Contact duration of impact, tD
Figure 1. Contact force control signal (left). Coesfeld ICCA impactor tool actuation (right).
It also records the following measurements
- Normal force
- Normal displacement
- Friction force
- Friction displacement (i.e. wheel rotation)
- Abrasion depth
Figure 2. Normal and friction impact forces and displacements during a single impact.
The Coesfeld ICCA instrument improves on J. R. Beatty’s 1979 “BF Goodrich Cut and Chip” (BFG) test in several ways. Perhaps the chief improvement is that the force and duration of the impact are accurately controlled and measured. The BFG test suffers from two major problems: 1) that the impact is passively applied by means of a weighted beam whose natural impact frequency is influenced by the stiffness of the rubber compound, and 2) that the impact forces and displacement are not measured and not easily relatable to applications. By quantifying the impact conditions of the test, the Coesfeld ICCA offers the opportunity to match those of the actual application.
As the Americas distributor for Coesfeld testing instruments, Endurica is proud and excited to add the Coesfeld ICCA to our portfolio of testing services and testing instruments. Reach out to us today if you have a need for testing services on the ICCA, or if you would like to bring the Coesfeld ICCA to your lab.
Figure 3. Endurica President Will Mars and Vice President Tom Ebbott with the newly installed Coesfeld ICCA at partner ACE Laboratories.
