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Methods for measuring strains at high rates.

Duncan, B C (1998) Methods for measuring strains at high rates. NPL Report. CMMT(A)133

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Finite element analysis (FEA) is a powerful technique for the design and analysis of structures sustaining impacts. However, reliable predictions require both a suitable model for the material behaviour and material properties at appropriate strain rates. An aim of one of the tasks in project PAJ2 of the DTI Performance of Adhesive Joints programme was to establish methods for determining such material properties at high strain rates that would be suitable as input for FEA. One particular problem is measuring strains at these high strain rates. Test machines can carry out tensile tests at speeds of around 1 ms -1. These speeds give strain rates of 10s-1 or more. Conventional extensometry is unreliable at these speeds. As part of project PAJ2, a high scan-rate, linescan camera has been developed to determine strains in the high rate tests. The measurement and analysis procedures for this instrument are complex and it is not yet suitable for carrying out routine measurements. However, it has confirmed that a technique devised for estimating strains from the movement of the test machine crosshead gives a reasonably reliable estimate of the strains. Both of these methods are described in this report.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CMMT(A)133
Subjects: Advanced Materials
Advanced Materials > Mechanical Measurement
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/2782

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