STEP Lab’s electrodynamic testing machines carry out DMA tests on specimens of all sizes, from small material samples to components, at frequencies of up to 1,000 Hz and with precise control of force and displacement.
DMA (Dynamic Mechanical Analysis) is a test that characterises the properties of a material as a function of temperature, time, frequency, stress and atmosphere. A small sinusoidal deformation is applied to the specimen, under force or displacement control, and its response is measured.
The typical test parameters are derived from the amplitude of the response and the phase shift:
Preservation module (E’)
The elastic component: the energy that the material returns.
Loss modulus (E’’)
The viscous component: the energy dissipated by the material.
Tan δ
The ratio of E” to E’. This indicates damping.
Glass transition temperature (Tg)
It is identified by the peak in tan δ as the temperature varies.
Up to 1,000 Hz on UHF machines.
Also suitable for rigid materials and test specimens with a large cross-sectional area.
DMA, fatigue and other dynamic tests.
100% electric. Ideal for laboratories.
Ultra-high-frequency (UHF) machine
STEP Lab offers three ranges of electrodynamic machines for DMA testing: UD, XUD and UHF. The choice depends on the material, the force and the frequency required.
UD – Frequencies up to 250 Hz
| UD SERIES | UNITS | UD01 | UD04 | UD08 | UD012 | UD025 | UD030 | UD050 | UD100 |
|---|---|---|---|---|---|---|---|---|---|
| Max. Dynamic Force | kN | 0.70 | 4.00 | 8.00 | 12.00 | 25.00 | 30.00 | 50.00 | 100.00 |
| Max. Static Force | kN | 0.54 | 2.90 | 5.80 | 8.70 | 14.50 | 19.20 | 29.00 | 58.00 |
| Max. Test Speed | m/s | 2.00 | 2.00 | 2.00 | 2.00 | 1.00 | 2.00 | 1.00 | 1.00 |
| Max. Test Frequency | Hz | 125* | 125* | 125* | 125* | 100 | 125* | 100 | 100 |
| Standard Stroke | mm | 80 | 250 | 250 | 250 | 130 | 100 | 130 | 130 |
| Cooling | Air | Air | Air | Air | Water closed circuit | Water closed circuit | Water closed circuit | Water closed circuit | |
| Working Temperature | °C | 5-30 | |||||||
| Facility Requirement | 3PH 400V | ||||||||
XUD – Frequencies up to 600 Hz
| XUD SERIES | UNITS | XUD05 | XUD010 | XUD020 | XUD030 |
|---|---|---|---|---|---|
| Max. Peak Force | kN | 5.5 | 10.4 | 20.5 | 31.2 |
| Max. Dynamic Force | kN | 1.5 | 2.7 | 5.4 | 8.1 |
| Max. Static Force | kN | 1.0 | 2.1 | 4.2 | 6.3 |
| Max. Test Speed | m/s | 6.0 | |||
| Max. Speed at Peak Force | m/s | 4.0 | |||
| Max. Test Frequency | Hz | 600 | |||
| Standard Stroke | mm | 220 | |||
| Working Temperature | °C | 5-30 | |||
| Cooling | Air | ||||
| Facility Requirement | 3PH 400V | ||||
UHF – Frequencies up to 1000 Hz
| UHF Specs | UNITS | UHF04 | UHF010 | UHF020 | UHF025 |
|---|---|---|---|---|---|
| Max. Peak force | kN | 4.40 | 11.10 | 20.75 | 24.75 |
| Max. Dynamic force (Sinusoidal fatigue) | kN | 2.25 | 5.55 | 10.65 | 15.85 |
| Max. Static force | kN | 1.25 | 3.20 | 6.20 | 9.30 |
| Max. Test speed@Peak force | m/s | 5 | 5 | 2.7 | 2.7 |
| Max. Test frequency | Hz | 1000 | 1000 | 600 | 600 |
| Standard stroke | mm | 115 | 115 | 160 | 160 |
| Working temperature | °C | 5-30 | 5-30 | 5-30 | 5-30 |
| Cooling | - | Air | Air | Air | Air |
| Facility requirement | - | 3PH 400V | 3PH 400V | 3PH 400V | 3PH 400V |
| Standard | Materials | Mode / method | Quantity determined | Notes |
|---|---|---|---|---|
| ISO 6721-1 | Plastics | General principles | Definitions and principles shared by all parts of the series | Introductory part |
| ISO 6721-2 | Plastics | Torsion pendulum | Storage and loss components of the torsional modulus versus temperature | Low frequency |
| ISO 6721-3 | Plastics | Flexural vibration, resonance-curve method | Dynamic mechanical properties in flexure | Resonance method |
| ISO 6721-4 | Plastics | Tensile vibration, non-resonance method | Dynamic mechanical properties in tension | Forced vibration |
| ISO 6721-5 | Plastics | Flexural vibration, non-resonance method | Dynamic mechanical properties in flexure | Forced vibration |
| ISO 6721-6 | Plastics | Shear vibration, non-resonance method | Complex shear modulus G* | Typical frequencies from 0.01 to 100 Hz, storage moduli from 0.1 to 50 MPa |
| ISO 6721-7 | Plastics | Torsional vibration, non-resonance method | Dynamic mechanical properties in torsion | Better suited than shear mode for materials above 50 MPa |
| ISO 6721-11 | Plastics | Temperature scan | Glass transition temperature | Tg by DMA |
| ISO 6721-12 | Plastics | Compressive vibration, non-resonance method | Dynamic mechanical properties in compression | Forced vibration |
| ISO 4664-1 | Vulcanized and thermoplastic rubber | General guidance on free and forced vibration methods, for both materials and products | Dynamic properties (stiffness, damping) | Excludes rebound resilience and tests aimed mainly at fatiguing the rubber. 2022 edition |
| ISO 4664-2 | Vulcanized and thermoplastic rubber | Torsion pendulum at low frequencies | Shear modulus and mechanical damping | 0.1 to 10 Hz, very small strains |
| ASTM D4065 | Plastics | General practice for gathering and reporting DMA data | Elastic and loss moduli and transition temperatures versus temperature, frequency or time | 2020 edition |
| ASTM D4092 | Polymers | Terminology | Definitions of terms used in dynamic mechanical measurements | 2021 edition |
| ASTM D5023 | Plastics | Flexure, three-point bending | Dynamic mechanical properties | |
| ASTM D5418 | Plastics | Flexure, dual cantilever beam | Dynamic mechanical properties | |
| ASTM D5026 | Plastics | Tension | Dynamic mechanical properties | |
| ASTM D5279 | Plastics | Torsion | Dynamic mechanical properties | |
| ASTM D4440 | Plastics | Melt rheology | Dynamic mechanical properties of the melt | |
| ASTM E1640 | Amorphous and semi-crystalline materials | DMA | Locating the glass transition region and assigning Tg | For materials with a modulus from 0.5 MPa to 100 GPa. 2023 edition |
| ASTM D7028 | Polymer matrix composites | DMA | Glass transition temperature (DMA Tg) | |
| ASTM D5992 | Vulcanized rubber and rubber-like materials | Guide to vibratory methods: free resonant, forced resonant and forced non-resonant | Stiffness, damping and dynamic modulus | Also applicable to finished products |
| ASTM E1867 | DMA instruments | Calibration | Temperature calibration | 2022 edition |
| ASTM E2254 | DMA instruments | Calibration | Storage modulus calibration | 2024 edition |
| ASTM E2425 | DMA instruments | Verification | Loss modulus conformance | 2021 edition |
By material type and test specimen
What does a DMA test involve?
A DMA (Dynamic Mechanical Analysis) test applies a small deformation, or a force, oscillating in a sinusoidal manner to the specimen, and measures its response: the amplitude and the phase difference between stress and strain. From this data, the storage modulus, loss modulus and tan δ are calculated. The test is carried out by varying the frequency, temperature or amplitude, whilst the machine controls the force and displacement.
What sort of machine do I need for a DMA test?
It depends on the force, frequency, specimen size and test temperature. STEP Lab offers three ranges of electrodynamic machines: UD, XUD and UHF. The UHF models operate at up to 1,000 Hz, with peak forces ranging from 4.4 to 24.75 kN; the XUD models at 600 Hz and 31.2 kN; and the UD models at 250 Hz and 100 kN. A climatic chamber is also required for temperature testing.
What does a DMA test measure, and why is it important?
A DMA test measures the stiffness of the material (storage modulus E’), the energy it dissipates (loss modulus E”) and the damping (tan δ), as well as the glass transition temperature. This is important because it shows how the material behaves under real-world conditions: how its stiffness changes with temperature and frequency, how effectively it dampens vibrations and noise, and at what point it changes state. It is used to select and compare materials, design components such as bearings and bushings, and monitor quality.
What are the different types of DMA tests?
There are three main types of scan. The frequency scan, carried out at a constant temperature, shows how the moduli change with frequency. The temperature sweep, at a fixed frequency, identifies transitions such as Tg. The amplitude sweep verifies the linearity limit and phenomena such as the Payne effect in filled rubbers. In addition, there is the time test, for ageing or cross-linking, and the master curves, constructed by combining frequency and temperature with the time-temperature overlay.
Which deformation mode should I use for DMA?
It depends on the material, the shape of the test specimen and how the part will be used. Tensile testing is suitable for films, fibres and thin test specimens. Compression testing is suitable for cylindrical test specimens, foams and elastomers. Shear testing is suitable for softer materials: ISO 6721-6 specifies storage moduli between 0.1 and 50 MPa and recommends torsion testing for stiffer materials. Flexural testing (three-point or double cantilever) is suitable for rigid plastics and composites. It is advisable to choose the test method that most closely resembles the actual application, as different methods may yield results that are not directly comparable.
