Strain measurement is a key component of mechanical testing and is required by nearly all relevant ASTM and ISO standards. Instron offers a wide range of strain measurement devices to suit every material and application. From simple bonded strain gauges to the most advanced video extensometry, all of our devices are designed and manufactured by Instron engineers to meet our own stringent accuracy standards. If your testing application requires a creative solution, our Custom Engineering Group is available to design and implement a strain measurement solution that meets your needs.

Strain Measurement Devices

AVE 2 Advanced Video Extensometer


Non-Contacting Video
A video extensometer is a non-contacting extensometer that can measure deformation by tracking the movement of two attached markers on the specimen, using high-resolution digital camera technology. Key advantages of video extensometers are that they do not exhibit any influence on the test specimen, problems with knife-edge slippage are eliminated, and errors due to inertia of moving parts is also eliminated.

Overview
Travel GL: > 5, 10 mm, 60 mm, 200 mm, 500 mm
Temperature Range Can be used with a chamber and bath
Automatic or Manual Automatic
Suitable For Almost every material
Common Standards Conforms to the most rigorous testing standards, including ISO 527 and ASTM D638
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AutoX750 on 5900 Series Universal Testing System


Automatic Contacting
The need for increased specimen throughput has created a demand for faster, more reliable, and more accurate materials testing routines. Automatic contacting extensometers provide this capability by enhancing the productivity of testing laboratories that can take advantage of the automatic gauge length positioning feature, as well as the automatic attachment to the test specimen.

Overview
Travel GL: > 10 mm
750 mm
Temperature Range Ambient (10° to 38° C)
Automatic or Manual Automatic
Suitable For Almost all materials and a variety of geometries, such as strip, round, hexagonal, and flat shape
Common Standards ASTM D638, ISO 527-2, ASTM D412, ISO 37, ASTM D790, ISO 178, ASTM D882, ISO 527-3, ASTM D3039, ISO 527-4, ASTM F2516
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300DX Tension Space with Clip on Extensometer


Static Axial Clip-On
Clip-on extensometers for static testing offer speed of attachment and ease of use. Their light-weight, rugged cross brace design eliminates errors caused by physical distortion, while built-in protection ensures that damage is not caused by over-extension. The low operating-force arms of the extensometer reduce the possibility of knife-edge slippage when testing hard or smooth surfaced materials.

Overview
Travel Wide variety of selections
Temperature Range -100° to 200° C
Automatic or Manual Manual
Suitable For Static clip-on extensometers are used for static strain measurement on a wide range of materials and specimens including metals, plastics, and composites
Common Standards ASTM D638, ISO 527-2, ASTM E8, ISO 6892, ASTM D3039
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Long Travel Extensometer on Single Column Universal Testing System


Long Travel
The long-travel (XL) extensometer is a precise device for measuring strain in highly extensible materials. Designed for use with electromechanical testing instuments, long-travel extensometers can be used to measure specimen elongations up to 10 in or 250 mm. The XL is designed to clamp directly onto to a specimen quickly and easily. It will adjust to incremental gauge lengths ranging from 0.5 in to 5 in, or 10 mm to 200 mm.

Overview
Travel GL: 10 mm - 100 mm
300 mm or 750 mm maximum travel
Temperature Range Ambient
Automatic or Manual Manual
Suitable For Elastomers, semi-rigid plastics, and films
Common Standards ASTM D412, ISO 37, ASTM D882, ISO 527-3
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Dynamic Clip On Extensometer


Dynamic Axial Clip-On
Clip-on extensometers for cyclic fatigue testing offer a versatile contacting solution for precise strain measurement. Their lightweight rugged construction and high natural frequency makes them ideal for high frequency and fatigue testing applications. The low operating force arms reduce the possibility of knife-edge slippage when testing hard or smooth surfaced materials.

Overview
Travel Wide variety of selections
Temperature Range -80° to 200° C
Automatic or Manual Manual
Suitable For Dynamic clip-on extensometers are used for cyclic strain measurement in tension, compression or reverse-stress through zero measurements on a wide range of materials and components including metals, plastics, and composites
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Biaxial Extensometer on Composite Specimen


Averaging Axial and Biaxial
Averaging axial and biaxial extensometers are used for testing advanced composites, rigid plastics, and metals. Average axial strain is determined from independent strain measurements on opposite sides of the specimen. The use of average strain eliminates errors due to specimen bending and allows the determination of precise modulus values. By integrating a transverse strain transducer, the extensometer can simultaneously measure average axial and transverse strain allowing the determination of Poisson’s ratio. Generally, this type of extensometer is intended for measuring small strains such as those used for the determination of elastic properties.

Overview
Travel GL: 25 / 50 mm
Axial travel: 1.25 mm
Transverse travel: 0.5 mm (biaxial versions)
Temperature Range -200° to 200° C
Automatic or Manual Manual
Suitable For Static tests to determine elastic properties (modulus and Poisson’s ratio) of composites, rigid plastics, and metals
Axial Info    Biaxial Info
 



LVDT


LVDT
Linear variable differential transformer (LVDT) displacement transducers are measuring devices that measure the displacement of the load frames of materials testing systems. They feature an LVDT as the active element, and are designed for use on both electromechanical and hydraulic testing systems.

Overview
Temperature Range -40° to 100° C
Automatic or Manual Manual
Suitable For Almost all materials – dependent on travel
Common Standards ISO 178, ASTM D1621, ASTM D575-91, ASTM A370
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Bonded Strain Gauge


Bonded Strain Gauge Adapters
From aerospace to construction, strain gauges are used in a variety of industries to measure strain in both materials and structural testing. Instron strain gauge adapters allow a single strain gauge to be used with any standard Instron strain channel.

Overview
Gauge Resistance 120 ohm and 350 ohm models available
Gauge Factor 1.5 to 2.5
Full Scale Strain 50,000 με / 5%
Strain Gauge Connections Spring-loaded terminals
Controller Connection Instron standard 25-way connector
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High Temperature Extensometers



High-Temperature
Most clip-on contacting extensometers use strain gauges to measure strain on the specimen. These devices use a high-temperature capacitive sensor allowing them to be used up to maximum temperature of most environmental chambers used in materials testing.


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Deflectometer



Flexural Deflectometers
The deflectometer on its own is not a strain measuring device – it is simply a spring loaded plunger that is used in conjunction with an extensometer, whether it be a clip-on, an automatic contacting extensometer (AutoX750), or a video extensometer (AVE 2). It is primarily used for flexural tests.


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Circumferential Extensometer



Circumferential
Circumferential extensometers are used to determine the circumferential deformation of cylindrical specimens. The extensometer is attached around the circumference of the specimen using a chain assembly. As the specimen deforms under compression, the change in circumference is monitored by the extensometer.


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Crack Opening Displacement Gauge



Crack Opening Displacement Gauges
Crack opening displacement (COD) transducers are designed specifically to perform standard ASTM and ISO fracture mechanics tests (both cyclic and static), covering all common specimen geometries (CT, SEB, Centre Crack, Arc Shaped).
 


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Transverse Clip-On Extensometers



Transverse Clip-Ons
Transverse clip-on extensometers are used to measure displacements across the width or diameter of a test specimen. They are commonly used for the measurement of Poisson's ratio and transverse strain on anisotropic materials such as composites. A special version is available for determining "r" value of sheet metals.


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Knife Edges Clips and Parts for Extensometers



Replacement Knife Edges and Clips
A range of optional parts and replacement parts are available for extensometers. Replacement knife edges can be used when existing ones become worn or damaged. Optional clips allow different specimen sizes to be tested.
 


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Accessories Catalog


Accessory Catalog
Find even more extensometers in our 7th Edition Accessory Catalog, in addition to accessories for extensomters, such as knife edges, clips, connecting cables, and more.


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