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Ultimate Tensile Strength

Ultimate Tensile Strength

Ultimate Tensile Strength

While you may be unfamiliar with the term ultimate tensile strength, you have likely reaped the benefits of its measurement. From the aerospace industry to the beverage industry, there are countless ways that tensile strength has impacted the goods and services you use on an everyday basis.

For example, if you have ridden an elevator at a mall or hotel, you have likely noticed the weight limit printed somewhere inside. This limit indicates how much stress the elevator’s cables can endure before breaking. This limit was identified through tensile strength testing. As long as the weight limit is not reached, passengers ride with confidence in the elevator’s cables. Though you may not fully understand tensile strength, you rely on it for safety and quality all the time.

Keep reading to learn more about the importance of tensile strength and how it impacts the manufacturing process.

What is Tensile Strength?

Tensile strength refers to a specific material’s ability to resist being pulled or stretched apart. The force of stretching or pulling is called tensile stress. It is an important characteristic for many different objects ranging from rubber to metal. Tensile strength indicated a material’s ability to withstand stress before weakening.

What is Tensile Strength?

A series of tests are conducted to ensure that the objects and materials manufacturers are using are strong enough to support and withstand specific amounts of weight and tension. These tests are typically carried out by destructive engineering in material testing labs.

If you were to pull a piece of yarn with its ends in opposite hands, you can test its tensile strength. Of course, this would not be as scientific and specific as engineering testing, but you can get a great idea of how what these tests are seeking out. The yarn will stretch until it is pulled taught. Beyond this point, the yarn piece will likely begin to deform. If it is stretched beyond its ultimate tensile strength, it will not bounce back to its original form or it may even begin tearing apart.

Understanding a material’s ability to withstand weight and stress is important for the manufacturing process. Tensile strength impacts what materials are used and not used. For products that will need to lift or pull considerable weight, manufacturers need to know what characteristics to look for when choosing materials. Depending on their needs, they may seek out materials with high or low tensile strengths.

Features of Materials with Differing Tensile Strength

Features of a Material with High Tensile Strength include:

  • Resistance to breakage and deformation from stretching
  • Used for tools and mechanisms that lift, hoist, or pull materials
  • Durable and relatively strong

Examples of Materials with High Tensile Strength include:

  • Steel
  • Bamboo
  • E-glass
  • Silicon
  • Diamonds
  • Carbon fiber
  • Spider silk

Features of a material with low tensile strength include:

  • Typically have lower densities
  • Typically more malleable
  • Deform when stretched
  • Shatter or break when pulled

Examples of materials with low tensile strength:

  • Acrylic
  • Rubber
  • Concrete
  • Polyester
  • Aluminum
  • Copper

How is Tensile Strength Measured?

The tensile strength of a material is determined through testing processes that take place in material testing labs.  During this testing, certain amounts of force are applied to the specimen in different directions to see how much tension can withstand before breaking.

How is Tensile Strength Measured?

To prepare for the tensile strength testing process, an engineer will secure the material to a tensile machine. Usually, these machines attach to the object in at least two places. Then, the engineer will have the tensile machine adding continuous tension by stretching and pulling the specimen apart.

Engineers closely monitor the process and record changes to the material on a stress-strain curve until the material breaks or deforms. Tensile strength is generally measured by the amount of force per cross-sectional area. These tests are used for several reasons such as:

  • Identifying and choosing high-quality materials for manufacturing
  • Predicting the performance of the materials for real-time uses
  • Determining a program’s compliance with specifications, contracts, and quality standards
  • Testing new products
  • Determining if the material meets safety standards

While engineers carry out these tests to ensure product parts are meeting standards, they are also seeking out specific information about the material they are testing. Tensile strength tests typically give engineers valuable information about the material’s properties such as:

  • Maximum load: The greatest amount of weight a material can withstand without breaking or becoming weaker.
  • Ductility: The extent to which a specimen can withstand disfigurement before any sort of rupture occurs.
  • Bend: A material’s ability to bend without fracturing on either convex and concave sides.
  • Elongation: The elasticity and ductility of a product when weight is constantly adding stress and lengthening the material.

The data found during testing can be utilized later on as manufacturers decide on what materials and goods to use in their processes. Tensile strength is not measured in these categories. Instead, during this testing, engineers are measuring tensile strength in three different ways:

  • Yield strength: A material’s yield strength refers to the most amount of stress that the material can endure before breaking.  Testers are also looking for a material’s yield point in which the changes that occurred during testing are not reversible and the specimen is lastingly deformed.
  • Ultimate strength: Ultimate strength is the absolute most stress that a material can resist while being pulled or stretched. The ultimate tensile strength equation is defined as the maximum load divided by its original cross-sectional area. The ultimate strength is an indication of ultimate tensile stress as well.
  • Breaking strength: The specimen’s breaking strength refers to a point of tension in which a material is no longer able to resist stress and the material breaks.

What is the Stress-Strain Curve?

The stress-strain curve displays the behaviors of a specimen as force is gradually applied to it.  The curve is documented as a graph during tensile strength testing.  The stress-strain curve is used to understand how the material passes through different stages of change before breaking or fracturing.

What is Stress?

Stress is typically measured in pounds per square inch. This is the ratio of tension or force applied to the specimen’s cross-sectional area where the force is implemented. Stress refers to the act of stretching in tensile strength testing.

What is Strain?

Strain refers to the deformation of a specific material as tension or force is applied. The material may change form and shape. To measure strain, an engineer finds the deformation inches for each inch of the specimen’s full length. Strain refers to the impacts on the material during tensile strength testing.

The Main Regions of the Stress-Strain Curve

The Main Regions of the Stress-Strain Curve

The stress-strain curve is broken down into multiple regions. Each region represents the changing behaviors of a material, such as steel or carbon fiber. Each section of the curve indicates various mechanical properties. The three main regions include:

Yield Strength

Yield strength, or yield stress, is the point at which a specimen experiences plastic deformation. In this stage, the specimen returns to its original shape and form when tension or force is taken away. A material’s form is not reversible once it reaches the yield point on the stress-strain curve.

The yield point is the limit at which the material will not go back to its original form even after all tensions are removed.

Strain Hardening

After a specimen moves beyond the yield point, it enters the strain hardening region. During this phase, the material’s microstructure is experiencing changes. Some materials are purposefully stretched or pulled to reach the strain hardening region as this can make the structure stronger.

For example, aerospace alloys are developed to meet the strain hardening phase. This strengthens alloys and allows them to be more durable. Strain hardening is also referred to as work-hardening and, in some cases, cold-working.

Ultimate Strength

The ultimate strength is an important point on the stress-strain curve between strain hardening and necking. Ultimate strength refers to the maximum amount of stress that a specimen can endure without weakening.

However, if a specimen has reached ultimate strength during testing, then the structure will begin to deform if the stress is maintained or increased. On the stress-strain curve, the ultimate strength represents the absolute maximum tolerance of an object before it begins weakening.

Necking

After a specimen reaches its ultimate strength, it begins to lose strength. The necking phase occurs when a material’s cross-sectional area decreases in size due to the material no longer being able to endure the stress.

At this point, the strain on the material increases. The material in question is headed towards fracture.

Fracture

When a specimen fractures during testing, this means that the material is no longer in one piece and has separated. The specimen could break, fragment, crack or split.

The fracture point on the stress-strain curve indicates that the material reached failure and could not withstand the stress.

Why is Tensile Strength Measurement Important?

It is necessary to have confidence in the structural integrity of the products and machines we use every day. This applies to everything from seatbelts to airplanes to athletic sneakers. Tensile strength measurement allows a multitude of industries to keep creating higher quality, longer-lasting products that keep consumers safe. Tensile strength measurement is essential for the following two reasons:

  • Safety standards: Above all, safety is the most important reason for measuring tensile strength. Understanding the durability and toughness of products allows for security. Without testing, operators would not know the maximum weight limits on machines like elevators or amusement park rides. Ignoring tensile strength testing results is dangerous as the materials can weaken or even break when overloaded.
  • Quality standards: Tensile strength measurement give us important information about the structural integrity and dependability of products or machines. Testing allows companies and manufacturers to choose better quality materials to incorporate into their products. It also provides important information for the consumer so that they have a clear understanding of how to properly utilize items without getting injured or damaging the goods.

Industries that Utilize Tensile Strength Testing

There are many industries that utilize tensile strength testing.

Electronics and Electrical Industry

The electronic industry applies tensile strength testing to its components, such as:

  • Circuit board components
  • Cables
  • Electrical wires
  • Connectors

Construction Industry

Structural stability is one of the most vital parts of any construction job. This industry focuses on strength and safety. They do this by testing the tensile strength on materials, such as:

  • Geotextiles
  • Timbers
  • Beams
  • Adhesives
  • Sealants,
  • Safety support nettings
  • Mastics

Automotive Industry

Safety and quality assurance are important aspects of the auto industry. They test interior and exterior components to cater to both security and fuel costs. The following are tested for tensile strength:

  • Airbags
  • Seat belts
  • Handles
  • Mirrors
  • Window seals
  • Bumper moldings
  • Exterior fittings
  • Interior fittings

Aviation and Aerospace Industry

For safety and optimization, the aviation and aerospace industries conduct a lot of tensile strength testing. The following are some examples of objects or materials that this industry tests for durability:

  • Seat belts
  • Cables
  • Harnesses
  • Adhesive bonds
  • Alloy development
  • Nuts and bolts
  • Airframes

Beverage Industry

The beverage industry has to conduct tensile strength tests for packaging parts that consumers have to open including:

  • Ring pulls
  • Cork extraction forces
  • Packaging
  • Cans

Plastics and Rubber Industry

This industry tests joint strength and the general properties of both plastics and rubbers for the following:

  • Carbon fiber reinforced plastics
  • Interlocking components
  • Adhesions
  • Strength of plastic
  • Strength of rubber

Health/Fitness/Sports Industry

The heath and wellness industry utilizes strength tests to ensure the safety of athletes and the durability of sports and workout equipment. The following are some examples of materials that get tested:

  • Safety nets
  • Knot strength
  • Strings on equipment such as tennis racquets
  • Rubber soles
  • Fabrics for gear and clothing

Textiles Industry

Although it may not be obvious, the textiles industry conducts many tensile strength tests on its products to make sure all pieces are properly attached and functional. Examples include the following:

  • Security of buttons
  • Security of zippers
  • Seams
  • Fabrics
  • Thread
  • Cords

Medical Equipment and Device Industry

In the medical equipment and device industry, the tensile strength of materials can mean life or death. This industry must conduct testing and it does so on the following:

  • Surgical tubes
  • Dressings
  • Bandages
  • Surgical gloves
  • Needles
  • Suture materials
  • Catheters
  • Masks
  • IV connectors

Paper and Packaging Industry

The paper and packaging industry must test their products for tensile strength to ensure they can withstand the wear and tear of shipping and handling as well as day-to-day use. The following are commonly put through testing by the industry:

  • Adhesive bonds
  • Maximum loads
  • Seals
  • Caps
  • Plastic packaging
  • Cardboard packaging

Contact American Micro Industries

Contact American Micro Industries

Tensile strength is a critical component in manufacturing efforts. If engineers want to ensure products are safe and high quality, it is important to test the strength and durability of their components. At American Micro Industries, we are a custom component manufacturer that provides and creates the parts you need with CNC machining services. Tensile strength is a key component of any manufacturing process and we can assist you in finding the highest grade materials.

American Micro Industries works with engineers to bring the best quality products to you. Learn more about our manufacturing capabilities and get a free quote!