Continuous Automatic Measurement of Static Spring Constant and Dynamic Properties before and after Durability Tests on Rubber Vibration Isolators by Combination Test Software

Significance of the Topic

Rubber vibration isolators play a vital role in reducing noise and protecting machinery from harmful vibrations. Regular assessment of their static and dynamic properties is essential to ensure long-term reliability, meet industry standards, and avoid failures that could lead to downtime or safety hazards.

Objectives and Study Overview

This work presents a method for continuous, automatic measurement of static spring constants and dynamic properties of a market-available block-type round rubber vibration isolator. Measurements are performed before and after a durability test to evaluate performance changes in accordance with JIS K 6385.

Methodology and Instrumentation

The tests were conducted at room temperature (24 °C) using Shimadzu’s EMT-1kNV-50 electromagnetic fatigue and endurance testing machine equipped with:

• 10 kN manual non-shift type plate grips
• 1 kN load cell
• ±50 mm stroke actuator
• 4830 controller and Windows software with combination test functionality

Three sequential tests were automated: static spring property test (force control, 8 N/s, 280 N load), dynamic property tests at 15 Hz (±0.5 mm amplitude) and 100 Hz (±0.05 mm amplitude), followed by a constant-load durability test (2 Hz, ±320 N, 100,000 cycles). After endurance testing, static and dynamic tests were repeated.

Main Results and Discussion

Static measurements showed negligible change in spring constant (123.7 N/mm before vs. 121.4 N/mm after) and energy absorption. Dynamic properties at 15 Hz and 100 Hz exhibited slight reductions in absolute and storage spring constants, loss factors, and damping factors after durability testing. Time-waveform analysis revealed clean sine waves without zero-force rattling, indicating stable specimen fixation. Durability cycles up to 100,000 showed no significant drift, and no cooling device was required, suggesting minimal heat build-up.

Benefits and Practical Applications

Key advantages of this approach include:

• Full compliance with JIS K 6385 test methods
• Automated sequence reduces manual intervention and testing time
• High-frequency capability (up to 100 Hz) for dynamic analysis
• Accurate detection of property changes to guide product development and quality control

Future Trends and Opportunities

Advancements may include integration of active cooling to extend test duration, real-time data analytics for predictive maintenance, expansion to complex isolator geometries, and networked connectivity for remote monitoring and control within Industry 4.0 frameworks.

Conclusion

The combination of Shimadzu’s EMT series machine and dedicated software enables robust, high-throughput evaluation of rubber vibration isolators. Automated static and dynamic testing before and after endurance cycles delivers reliable data with minimal operator effort, supporting rigorous QA/QC and research applications.

Reference

1. Rubber vibration isolators – Testing methods JIS K 6385-2012
2. T. Yoshizawa, “Laboratory test method for vibration isolation rubber,” Journal of The Society of Rubber Science and Technology, Japan, Vol. 56, No. 2 (1983)