Tensile Force: Definition, Testing, and Examples

Tensile force is a core aspect of materials engineering. It refers to the force exerted when an object is pulled or stretched. When this happens, the force causes tension in the material, causing the axis of the applied force to elongate. It’s one of the most frequent types of testing we see from people in our industry. A strong understanding of this testing will help you choose the right equipment for your testing needs and ensure you’re performing the tests accurately.

What Is Tensile Force?

Tensile force is a force that stretches a material by pulling on it along its length. During the test process, the object is pulled and stretched. Understanding the applied force is essential for materials testing since it helps testers and researchers learn the stress limits of any object or material.

Imagine this test like a rubber band. You stretch the rubber band as far as possible, and eventually, it breaks. That process and the level of force needed to cause that break are similar to what happens during a tensile test.

Tensile Stress

While tensile force and tensile stress go hand in hand, they’re not actually the same measurement and have different testing processes.

Tensile force is the measurement of the external load of pulling force applied to a material. This is measured in Newtons (N). It’s a key factor in material selection for all types of materials.

Tensile stress is the ratio of a stretching force acting on a material to the cross-sectional area of that material in response to the applied tensile force. To find tensile stress, you divide the tensile force by the cross-sectional area of the material. Tensile stress is measured in units of pressure, typically Pascals (Pa) or pounds per square inch (psi).

Measuring Tensile Force

Across industries, tensile force is measured using material test machines like the Lloyd LD Series or universal testing machines like these Mark-10 Advanced Test Frames. These machines put the material through a controlled, gradually increasing tensile force until the material breaks or a set point is reached. The machines record the force in connection with the elongation of the material.

Testing Machines

Tensile testing machines are typically smaller and have fewer capabilities and configurations for testing force. There are a limited number of tensile-testing-only machines on the market today (and Johnson Scale doesn’t sell any at this time). Universal testing machines successfully meet the needs of most engineers, QA testers, and scientists.

Universal testing machines can be programmed for different tests and functions and have various capabilities to test force. They tend to have more options for grips and fixtures for more materials and test types. Universal testing machines are versatile and cost-effective; most tensile testing is done through these machines.

Material testing machines, like the Lloyd LD Series above, offer better performance, higher capacities, and more sophisticated software for calculations, such as elongation and modulus, than tensile testing machines or universal testing machines.

Importance and Examples

Tensile force is crucial to creating anything for quality and safety reasons. Final products, from clothing to wires to bridge cables, undergo this testing. Here are some examples:

Medical and Pharmaceutical: Our clients use tensile force testing for numerous applications in medicine and pharmaceuticals. Package peel force, suture strength, bandage strength, and tensile strength of orthodontic wire are just a few examples.

Automotive: Our clients use tensile force to test automotive parts like seat belt retraction force, switch activation force, windshield wiper arm force, and more. Many of the parts that go into making a car safe and reliable undergo this testing.

Aerospace: That’s right, even air travel needs tensile force testing. These tests are performed on materials used in aerospace machinery, like cables, wires, and electronic components.

Ropes: It may be a bit obvious, but ropes must be tested. Think about rock climbing. Most things you take hiking need to be tensile force tested: your ropes, your vest, your shoes, and your clothes. It shows how comprehensive this testing is and how much we need it to keep us safe and stress-free.

Tensile force testing is a crucial part of materials engineering and design. Ensuring you have the right machinery is a great place to start. Call us at 866-904-9734 or reach out to speak with one of our experts.