Quantifying and visualizing change: Strain monitoring of tapestries with digital image correlation

Abstract

A three-year research project at the University of Southampton (2007–2010) investigated whether monitoring techniques commonly used by engineers to assess the strength and durability of materials could be usefully applied to inform the condition assessment of historic tapestries. To date it has not been possible to obtain an objective picture of the overall condition of a tapestry; the study investigated whether it is possible to identify precursors of structural damage. The two techniques, digital image correlation (DIC) and optical fibre sensors, were used to monitor a representative wool fabric, specially woven tapestry samples, a newly woven tapestry, and historic tapestries, both in the laboratory and in situ in a historic house. This study first sets out to answer the question: can DIC be used to monitor and visualize strain in historic tapestries? It is shown that DIC can be used successfully. Secondly, it discusses the map function, a novel development which allowed the monitoring equipment to be moved, so that it could be used in situ in a historic house. Thirdly, it provides further details of the experimental work using optical fibre sensors to confirm the accuracy of the DIC technique.

Keywords:

• Tapestry
• Strain monitoring
• Digital image correlation
• Optical fibre sensors
• Strain map
• Map function
• Adhesives
• Polymer optical fibres

Acknowledgements

The project was funded by the UK Arts and Humanities Research Council. AHRC Research Grant award AH/D001404/1, £386 000. Principal Investigator: Frances Lennard. Co-investigators: Professor Janice Dulieu-Barton, Dr Alan Chambers. Team member: Dr Dinah Eastop. Post-doctoral researcher: Dr Chen-Chun Ye. PhD students: Djallal Khennouf (PhD awarded 2010), Helen Williams. The authors wish to thank all members of the project team and fully acknowledge their part in the research. The team was supported by members of the project Advisory Panel: Dr Paul Garside, Textile Conservation Centre (now at the British Library); Dr Kathryn Hallett, Historic Royal Palaces; David Hollis, LaVision; Ksynia Marko, The National Trust; David Thickett, English Heritage; Dr David Webb, University of Aston; Dr Christina Young, Courtauld Institute of Art. The team was also grateful to Nigel Wright, Property Manager at Hardwick Hall, the National Trust; Caron Penney, Head of the Tapestry Studio and the tapestry weavers at West Dean Tapestry Studio; Andy Lane, Marketing Manager, Intech, Winchester. The Institute of Physics supported a display at Intech.