What is an optical extensometer?

An optical extensometer is developed to measure local uniform strain on planar object. • The optical extensometer consists of two image sensors and a large format lens. • Virtual strain due to out-of-plane motions is eliminated by proposed correction sheet.

What are the types of extensometer?

There are two main types of extensometers: contact and non-contact.

How do you calculate extensometer?

Strain measurements are obtained by dividing the change in length by the initial length of the specimen (ε = ∆L/L). Axial extensometers provide strain data by clipping onto the specimen with their knife edges and measuring the displacement in length as load is applied and the specimen is pulled.

What are the basic requirements of extensometer?

The requirements for an extensometer are determined primarily by the characteristics of the material to be tested. This includes its shape and dimensions, test requirements and the formal standards that must be met. These define the gage length, accuracy, test sequence and environmental conditions.

How does video extensometer work?

Video extensometry incorporates a high-resolution digital camera with advanced real-time image processing to make highly precise strain measurements of a variety of specimen types. The video camera captures the image, which is transferred via an IEEE 1394 (Firewire) interface to a PC or laptop computer.

What is extensometer gauge length?

Extensometer Gauge Length is the distance between the extensometer’s initial measuring points on the specimen. If you are using a testing standard, check the standard for extensometer gauge length requirements. Many test standards specify the specimen dimensions and corresponding extensometer gauge length.

Why is an extensometer more accurate?

Extensometers measure strain (or displacement) directly on the test specimen. As a result, they provide far more accurate and repeatable measurements than measurements based on the motion of the testing machine’s grips, which include errors from the compliance of the testing machine.