What do tensile strength ratings mean for shock cord performance?

Tensile strength ratings are one of the most important specifications you will see when looking at shock cords. Essentially, these ratings provide a reliable measure of how much force a cord can take before it reaches its breaking point. Knowing what these ratings mean can be instrumental in helping you to choose cords are the most suited to your specific application, whether you are using them for activities like securing loads, creating tension in covers, or holding equipment in place. Here are the essentials of what you need to know. 

What tensile strength ratings mean for shock cords

Tensile strength basically ratings tell you how much force a cord can withstand before it fails. For shock cords, this is measured in terms of how much pulling force the cord can take before the fibres or the cord as a whole break. The overarching purpose is to give you a clear idea of the cord’s limits, which means you can plan for how it will perform when stretched, pulled, or loaded during use. The tensile strength is particularly important for applications where cords are under constant tension or subjected to sudden strain – such as in transportation, outdoor use, or heavy-duty fastening.

A cord with a higher tensile rating can tolerate more force, giving you assurance that it will hold up in demanding situations. It also enables you to assess whether a certain cord is suitable for repeated stretching without degrading too quickly. That means if you need to secure heavy tarpaulins, tie down cargo, or use cords in high-stress environments, knowing the tensile strength can give you peace of mind that the performance of the cord will stand up to the application at hand. 

How are tensile strength ratings determined?

Tensile strength ratings are primarily established through controlled testing, in which force is gradually applied until the cord reaches its breaking point. This process uses calibrated equipment to measure the precise amount of load the cord can handle, ensuring that the rating you see on the product matches its real-world capability. These tests often follow standardised procedures to maintain consistency, which means you can compare cords from different sources with confidence in the numbers you are reading.

This testing process is designed to take into account different stresses, like gradual increases in load or sharp, sudden pulls, both of which affect how a cord performs in different applications. And as far as the manufacturing process goes, these tests also help in quality control. They ensure that every batch meets the expected performance level. 

3 reasons tensile strength matters for your applications

As we have now established, a higher tensile strength gives you confidence that the cords will hold up under load, stay functional over time, and adapt to the variety of tasks you need them for. There are three key reasons why tensile strength is so important for ensuring suitability and success in any application:

• Safety

• Durability

• Versatility

So, let’s take a look at each one of these in a little more detail.

Safety is one of the most immediate reasons tensile strength matters. Shock cords with appropriate ratings give assurance they will not give way under strain while securing equipment, covering loads, or holding items in place. Choosing cords with the correct ratings reduces the risk of them failing in use, ensuring the safety of people and property alike. This is particularly important in settings where a snapped cord could cause injury or damage, such as during transport of goods or holding heavy covers in position during high winds. 

Durability is another key benefit. Cords that can withstand the forces they are exposed to can  resist fraying, maintain their elasticity, and remain effective even after repeated stretching. This essentially results in products that last longer, saving time on replacements and keeping your work running smoothly. Choosing cords with the correct tensile rating also reduces the likelihood of unexpected failures, which can interrupt projects or create safety hazards. What’s more, this durability makes the cords themselves more economical over time, as less is spent on replacements.

Finally, tensile strength contributes to versatility, enabling the cords to be used confidently across a broad range of applications. Light tasks at home, demanding outdoor setups, and commercial or industrial projects all benefit from cords rated for their specific demands. This flexibility makes it easier to tackle a wide spectrum of tasks without concern about whether your cords are up to the challenge. It also streamlines your kit, as well-rated cords can often serve multiple purposes, reducing the need for buying and storing different types for each job.

How to match tensile strength to your project requirements

When you are choosing shock cords, the first key consideration is naturally to think carefully about what you expect them to do. We would suggest starting by considering the maximum load they will need to hold, or the amount of force they will experience in your project. Once you have a clear idea of this, you can then compare it against the tensile strength ratings available, to make sure the cord you choose exceeds these requirements. As a general rule, it is better to work with a cord that has a higher rating than you expect to need, as it gives you an extra margin of safety.

It is also advisable to consider the environment in which the cords will be used. For example, cords that are exposed to outdoor elements – such as sun or rain – may degrade faster if they are not designed for those conditions, even if they have high tensile strength. In these situations, you need to look at cords with coatings or materials designed to handle exposure without losing their strength. Matching tensile strength involves considering both the ratings and how the cord will perform in the real-world conditions of your specific application.

Of course, if you need any extra peace of mind, or if you even have reason to believe that your shock cords may have been damaged in some way in the course of their normal operations, you may wish to test them out in the field. If so, we suggest reading our previous post on the subject. 

And of course, if you ever need any input or advice about the condition of your shock cords – or any replacements – this is where we can help here at Ibex Ropes Marina. We have unrivalled experience with shock cords, and serve a wide range of sectors across the UK and beyond, including aerospace, military and defence, subsea and offshore, and sport and leisure – just to name a few. If you require any expertise or advice, feel free to give us a call on 01706 360 363, and we will be happy to help however we can.