Historic tapestries are artworks created by weavers, which are modified over time by damage and conservation interventions. Several projects have examined the mechanical and hygroscopic properties of tapestries (e.g. Bilson, Howell and Cooke, 1997, Lennard and Dulieu-Barton, 2014, Duffus et al. 2012 and Alsayednoor et al. 2019). However, these studies either used replica samples made of artificially aged materials or relied on a single technique to analyse the mechanical behaviour of limited set of samples. The two research approaches, produced limited conclusions because of the highly variable mechanical response of historic tapestries.
The current research is a collaboration between University College London (UCL), Historic Royal Palaces (HRP), and IBM Research. It adopts a multidisciplinary methodology that incorporates knowledge from engineering, heritage science and conservation. The main body of the thesis is an extensive experimental campaign, whose aim is to characterise the strain response of historic tapestries subjected to environmental changes. A questionnaire complements the research by understanding the influence current conservation techniques have in structural changing tapestries.
A comprehensive study of physical and mechanical properties of historic tapestries was carried out. Universal testing machine (UTM) systems and digital image correlation (DIC) have been used extensively for testing historic tapestry fragments. Both methods were used in combination, while quantifying the physical heterogeneity of each fragment tested. In a second stage, the performance of a historic tapestry in open display was studied. A complete historic tapestry was tested inside an environmental chamber under different environmental conditions. Full field strain and local displacements were measured with DIC and newly developed IBM sensors respectively. With the study of weaved features in the tested tapestries, DIC showed that mechanics and dispersion in tensile results can be explained. Results from hygroscopic experiments inside the chamber quantified strain variation when tapestries are exposed to indoor uncontrolled environments.