Feature

Prestressing of compression springs

Most people who work with springs will be aware of the concept of prestressing, or at least the idea of a spring becoming shorter the first time it is used. However, the underlying mechanisms of why this occurs and the benefits beyond stabilising the dimensions of the spring are probably less well known…

03/05/2022 12:35:27

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Prestressing occurs when a spring is loaded to a point where the stress in the wire is high enough that it undergoes plastic deformation, but in a controlled manner. This plastic deformation causes a change in the spring,
which is visible as a reduction in the free length

What happens during prestressing?

When a relatively low stress (compared to the tensile strength of the material) is applied to most metals/alloys, they act by obeying Hooke’s Law. The
deflection experienced by a material (strain) under a load is directly proportional to the stress on it. This is known as the elastic region, and any material stressed in this way will return to its original dimensions after the stress
is removed. This relationship holds to a certain stress, known as the yield stress or elastic limit. After this point, the relationship between the stress and strain is not directly proportional. This can be seen in a tensile test,
shown in Figure 1. This is known as the plastic region. Material stressed beyond the yield stress, into the plastic region, will not return to its original shape after the stress is removed.

Read the full article in the May issue of DPA

Written By Sophia Bell

Sophia Bell is the Group Editor of DPA, Connectivity, and PBSI. She joined the team in 2020 as Assistant Editor after achieving a First-Class Honours BA in English Literature and Film Studies from the University of East Anglia. In her current role, she leads the editorial strategy, driving digital growth and ensuring each title continues to deliver trusted, relevant insight for engineering and manufacturing professionals.