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David Ross-Pinnock Progress Report Q1 2016

Research Theme 2: Quarterly Report Q4 2015


David Ross-Pinnock

Research Theme 2:

Model-based and physical measurement methods for establishing the uncertainty of the spatial fidelity of large, complex tools and parts due to gravitational effects and thermal gradients


Work Package 2.1 – Hybrid model-based and physical measurement technique for structural fidelity
Work Package 2.1 – Hybrid model-based and physical measurement technique for structural fidelity
Work Package 2.2 – Strategy for measurement data acquisition and fusion with model data

Progress Update

Large scale product assembly is often carried out in thermally unstable environments that do not meet the metrology standard of a uniform 20°C. A scaled-down assembly resembling an aerospace product has been designed and manufactured to study these effects and create a methodology for predicting the tolerance stack-up under thermal loading.

A conference paper based on the lab-based aluminium frame study in which the frame is subjected to convective heating has been presented at the 9th Digital Enterprise Technology conference in Nanjing, China.

Interpolation as an alternative to the thermal finite element method for populating structural analyses with temperatures is currently being explored. This appears to offer a quicker and less complex method than the thermal analysis. The simulation based upon interpolation currently gives displacement results that are slightly less accurate than the thermal analysis but not prohibitively so. Further work is being done to improve this method.

Measurements have been taken at Airbus in order to scale up the frame experiments carried out in the laboratory. A test rig structure used for wing-bending with a height of around 17 m was measured using a laser tracker and temperature sensors placed around the volume. This was a challenging metrology environment as whilst the heating was on, the temperature gradient was measured to be around 7-8°C vertically. A horizontal temperature gradient was also present. Ambient heating of the environment was also deactivated for a period of time causing the temperature gradient to reduce dramatically to less than 2°C vertically, allowing for contrasting measurement scenarios. Work is being done to model this structure computationally to see how well displacement predictions agree.

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