Influence of temperature and measurement uncertainty in sustained load testing on bonded fasteners

Abstract Sustained load testing on bonded fasteners is used for the long‐term forecast of the fastener displacement behaviour. The application of the Findley law as extrapolation method is an intensively discussed topic. This method uses a power law to forecast the long‐term behaviour. As a result, also the measurement uncertainty from measured displacements and temperature effects are extrapolated over time. Currently sustained load tests for product qualification of bonded fasteners are regulated in the European Assessment Document EAD 330499, in which certain measurement intervals and the required accuracy are defined. Recent improvements in data acquisition lead to possible reductions of measurement intervals in order to make long‐term forecasts more precise. Therefore, measurement uncertainty of the displacement measurement gains importance. Considering this issue, the influence of the measurement device itself, the location of displacement measurement in the test setup and temperature changes are discussed within this contribution.