ISO 18437-6:2017

Overview

ISO 18437-6:2017 - "Mechanical vibration and shock - Characterization of the dynamic mechanical properties of visco‑elastic materials - Part 6: Time‑temperature superposition" - defines a standardized method to acquire and analyze dynamic visco‑elastic data using the time‑temperature superposition (TTS) principle. It is applicable to thermorheologically simple materials tested at equilibrium and converts multiple isothermal frequency sweeps into a single master curve for prediction of material behaviour over a wide frequency (or time) range.

Key topics and technical requirements

• Scope & applicability: Works with test data from ISO 18437‑1 to ISO 18437‑5, ISO 6721‑4 to ISO 6721‑7 and ISO 6721‑12. Applies to linear behaviour at small strains for thermorheologically simple materials.
• TTS principle: Horizontal (frequency/time) and vertical (modulus) shifting of isothermal data to produce a master curve representing behaviour at a chosen reference temperature.
• Shift factors: Definition and use of horizontal shift factor (lg aT) and vertical shift factor (lg bT); temperature dependence of shift factors is expected to be smooth. Common models (Arrhenius, WLF) are referenced; WLF discussed in ISO 18437‑4 and ISO 4664‑1.
• Data acquisition requirements: Sufficient temperature/frequency coverage and overlap between neighbouring isotherms. Example of good quality DMA data: measurements every 5 °C with frequencies such as 0.1, 0.2, 0.3, 0.5, 1, 2, 3, 5, 10, 20, 30 Hz, or at least one decade overlap.
• Thermorheological simplicity check: Use of wicket plots (loss factor vs. storage modulus) and consistency checks to determine if TTS applies.
• Algorithms & verification: Standard includes a closed form shifting (CFS) algorithm when sufficient data are available and defines verification and uncertainty considerations.
• Uncertainty sources: Narrow overlap, large experimental errors (>10%), low data density, end effects, and choice of reference temperature.

Applications and who uses it

• Materials scientists and polymer technologists for characterizing visco‑elastic properties.
• Test laboratories using DMA or other dynamic mechanical tests to generate master curves.
• Mechanical and acoustic engineers designing damping, isolation and vibration-control systems who need long‑term or out‑of‑range frequency predictions.
• R&D and quality control in polymer manufacture and product development where time‑temperature dependent performance is critical.

Related standards

• ISO 18437‑1 to ISO 18437‑5 (principles, test methods, and data handling)
• ISO 6721‑4 to ISO 6721‑7 and ISO 6721‑12 (dynamic mechanical analysis methods)
• ISO 18437‑4 and ISO 4664‑1 (discussion of WLF and related TTS models)

Keywords: ISO 18437‑6:2017, time‑temperature superposition, TTS, visco‑elastic materials, master curve, storage modulus, loss modulus, shift factor, thermorheologically simple, DMA.