Material characterisation

TENSILE AND CREEP BEHAVIOUR WITH 2-D STRAIN MAPPING

Photograph of creep test being set up.The Reinhold Hermann creep laboratory at The Open University has recently been expanded and upgraded to provide a dedicated facility in support of our nuclear materials research programmes. It houses some 16 constant load frames, an Instron 100 kN slow strain rate machine and a Zwick 250 kN multi-purpose machine.

Tests can be conducted in various atmospheres (air, inert gas or vacuum) at temperatures up to 1000°C.

The averaged strain can be measured with special high-temperature gauges and/or mapped using digital image correlation (DIC). The ability to map the strains on the specimen surface allows, for example, the identification of the weakest region in cross-weld specimens, or determining multiple creep curves from a single test.

We pride ourselves for being one of UK pioneers in the application of DIC for mapping strains for high-temperature tensile/creep tests. StressMap’s experience with the application of the technique over the past decade has resulted in significant improvements on the technique and a number of academic publications. See some selected examples in our projects section.

FATIGUE ENDURANCE AND CRACK GROWTH RATES

Photography of post-test metal matrix composite test specimen with a plain-strain fracture and a fatigue crack.It is crucial to understand the fatigue behaviour of materials and structures subjected to cyclic loading, such as rotating components, chassis, pipes and integrated circuits. Here at StressMap we can perform bespoke tests at temperatures ranging from -150 to 1000°C.

We have the ability to control the tests based on load, displacement, strain, temperature, or even stress intensity factor by automatically measuring the crack length and feeding it back to the control software.

We pride ourselves for being able to adjust the setup, parameters and measured variables according to the needs of our clients, offering specialist advice on how to solve each problem the best way possible.