DMYO-V with sample

The concept of the new “Dynamic Mechanical Yerzley Oscillograph – V” is based on the venerable “Advanced Yerzley Oscillograph – IV as per ASTM D945-16”. Both are based on weights on an oscillating beam always testing elastomers at the natural frequency of the configuration.

  • AYO-IV has two possible moment arms, 5" or 10"; whereas, DMYO-V has a variable moment arm that automatically adjusts between 4" and 11". The weight table is motorized, it can setup automatically at any specified strain.
  • DMYO-V has a load cell in addition to a displacement transducer. Both load and displacement are measured simultaneously, enabling:
    • The observation of the phase lag between Load and Displacement.
    • The comparison of measured Phase Angle to the theoretically calculated (ASTM 5992) Loss Angle.
  • The manual “Step Wise” hysteresis test of the AYO-IV is fully automated on the DMYO-V. The static hysteresis test is user-programmable and normally runs unattended on this test machine.
  • The Dynamic Test on the DMYO-V is automated with a magnetic trigger, which enhances repeatability.
  • The data processing and parameter evaluation procedures have been improved with noise elimination and data-smoothing algorithms.
  • Minima and Maxima detection mechanisms use least square error curve fitting to improve accuracy. This is crucial for evaluating phase angles.
Specimen with Shore Harness 40
Figure 1. Point Modulus and Dynamic Modulus vs. Measured Load for NR with Shore A 40
Specimen with Shore Hardness 70
Figure 2. Point Modulus and Dynamic Modulus vs. Measured Load for NR with Shore A 70



  • Automotive door seals: Dynamic Modulus (low values), Dynamic/Static Ratio of moduli (low values), help to design the automotive door seals correctly for better sound-proofing and longevity.
  • Engine mounts: Yerzley Resilience (low values) and Yerzley Hysteresis (higher values) as well as Impact Energy (low values), Phase angle (high values) will absorb vibration energy much more efficiently for smooth riding.
  • Windshield wipers: Dynamic Modulus (low values), Dynamic/Static Ratio of moduli (low values), helps to design the wipers correctly for better and long-term wiping function. Climate change (summer & winter) should have minimal effect on the wiping function.


Seismic Pads: Dynamic Modulus, Impact Energy, Phase angle all have to have high values for high damping function. Natural frequency around 5 to 9 Hertz may also be useful for the design criteria.

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