Composites News

Strain Measurement Techniques for Composites Testing

Composite materials consist of two or more distinct phases. The most common type of high-performance composite materials are those consisting of continuous carbon or glass fibers embedded in a polymer matrix. These composite materials are now used in a wide range of critical structural applications.

Generally, the mechanical properties of composite materials depend on the material's direction.  Determining the tension, compression, and shear properties of composite materials requires a wide range of mechanical tests. The measurement of strain is a key requirement in all of these tests.

Traditional approaches to strain measurement in composites testing use contacting methods involving either bonded strain gauges or clip-on extensometers. However, recent developments in non-contacting strain measurement allow these systems to offer similar performance compared to contacting systems, as well as providing other benefits such as the ability to provide full-field strain maps.

Destructive and Non-Destructive Testing of Composites for Design and Manufacture

Early in the design cycle, the modeling and simulation of composite components for use in demanding structural applications requires a detailed knowledge of the properties of these anisotropic and inhomogeneous materials. The determination of these properties requires a wide range of mechanical tests, possibly over a range of temperatures, on materials conditioned in a variety of different environments. Later in the design cycle, mechanical tests on composite components are often employed to validate models by comparing model predictions to measurements on prototypes.

Non-Contacting Strain Measurements Techniques in Fatigue Testing of Polymer Matrix Composites

Instron's Dr. Peter Bailey and Maeve Higham published a paper titled Non-Contacting Strain Measurement Techniques in Fatigue Testing of Polymer Matrix Composites. This paper presents a short investigation of the benefits of non-contact strain measurement for monitoring and control of fatigue tests on composites. Recent developments in measurement technology offer the means to effectively measure both axial and transverse strain, instantly, throughout cyclic and highly dynamic tests. Several test scenarios are examined which demonstrate potential benefits of current state-of-the-art video extensometry for strain controlled fatigue tests on thermoplastic composites.

Exhibition Update

Instron recently attended the Advanced Engineering 2016 exhibition in Birmingham UK. This exhibition included Composites Engineering 2016. The exhibition gave us a chance to demonstrate our products and capabilities. We had application experts on the stand; they stayed busy speaking with both existing and new potential customers on a variety of topics.  

We demonstrated a number of products including:

• 5944 Electromechanical Testing System and BlueHill^® 3 Software: capable of tension, compression, shear and many other static tests on a wide range of materials and products
• Advanced Video Extensometer (AVE 2): non-contact strain measurement with an accuracy that is comparable with traditional contacting extensometers
• Digital Image Correlation (DIC): integrated DIC system based around the AVE2 which produces “full-field” 2D strain maps
• E1000 ElectroPuls™ Dynamic Testing System: a revolutionary low force dynamic test machine capable of a wide range of dynamic and static tests
• Examples from Instron’s wide range of composite test fixtures

An exciting new innovation that we bought to show for the first time was the Instron Virtual Reality experience. This used the latest 3D visualization technology to allow visitors to experience our systems and options in depth. In this way we were able to bring examples of large, high capacity single and multi-axis test systems to the show!

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