The importance of stress relaxation tests on a Texture Analyser and typical applications

Stress relaxation tests are critical for understanding the viscoelastic properties of materials, particularly how they respond to a constant strain over time. These tests are essential in industries such as food, pharmaceuticals, and materials science, where the long-term mechanical behaviour of materials can significantly impact product performance and quality.

What are stress relaxation tests?

Stress relaxation tests involve deforming a material to a fixed strain/distance and then observing the decrease in stress/force over time while maintaining the deformation. This behaviour is characteristic of viscoelastic materials, which exhibit both elastic (instantaneous recovery) and viscous (time- dependent flow) properties.

Why are stress relaxation tests important?

These tests help in characterising the viscoelastic nature of materials, providing insights into how materials behave under prolonged stress.

Stress relaxation tests can help determine how cosmetic products will behave when applied to the skin and help predict how materials such as polymers and plastics will perform under constant load conditions.

This type of testing also assists in the formulation of new products with desired mechanical properties by understanding how different compositions affect stress relaxation behaviour.

How a stress relaxation test works

Interpreting stress relaxation data

Stress decay curve: Plotting stress/force against time provides a stress relaxation curve, showing how stress/force decreases over the testing period.

Stress relaxation test on 2 powders

Relaxation time: The time it takes for the stress to reduce to a certain percentage of its initial value.

Comparison of stress relaxation data from cake
tested at days 1, 2 and 3 of storage

In the case of food testing, this is related to the term ‘springiness’, a desirable property denoting

product freshness.

Residual stress: The remaining stress in the material after a prolonged period under constant strain. Stress relaxation tests are essential for understanding the viscoelastic properties and long-term performance of materials. By conducting these tests, industries can ensure that their products meet quality standards and perform reliably in their intended applications. Whether in food, pharmaceuticals, or materials science, stress relaxation tests provide valuable insights that drive product development and quality control.

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There is a Texture Analysis test for virtually any physical property. Contact Stable Micro Systems today to learn more about our full range of solutions.

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For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

The TA.XTplusC Texture Analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

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