Mechanical response of wooden boards subjected to humidity step variations: climatic chamber measurements and fitted mathematical models

Dionisi-Vici, Paolo; Mazzanti, Paola; Uzielli, Luca

doi:10.1016/j.culher.2005.10.005

Cited by 46 publications

(12 citation statements)

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“…7 and 8, it can be confirmed that the horizontal displacements (recorded by LVDT 2, 6) follow a similar trend as that recorded by the horizontal strain gauges. The final displacements measured across an individual oak wooden board (as obtained by LVDT 2, 6) are comparable to those following from multiplying the local values measured by strain gauges at similar locations (i.e., SG 6,19) with the corresponding nominal LVDT width. The relative differences between these global and local deformation measures for the two mock-ups fall in between 3 and 35%, and indicate that the deformation across a board is not ideally uniform, due to the heterogeneity of the oak wood microstructure.…”

Section: Deformation Responsesupporting

confidence: 52%

“…In [16][17][18], experimental tests were combined with numerical modelling to characterize the fatigue behaviour of mock-ups of single board panel paintings under sinusoidal, relative humidity fluctuations. In [19] mock-ups of panel paintings were subjected to step variations of the ambient relative humidity, in order to obtain detailed insight into their hygro-mechanical response.…”

Section: Introductionmentioning

confidence: 99%

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Hygro-mechanical response of oak wood cabinet door panels under relative humidity fluctuations

et al. 2018

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Indoor climate fluctuations are regarded as one of the major risks for the emergence of damage in historical works of art. For a safe preservation of their art objects museums try to minimize this risk, which is typically done by imposing strict limitations on the indoor temperature and humidity conditions. The high energy demand resulting from this approach, however, undermines the aim of preeminent museums to execute a sustainable preservation strategy of their collections. A rational improvement of this aspect asks for detailed information on the history of museum objects, complemented by a thorough comprehension of the failure and deformation behaviour of museum objects under indoor climate fluctuations. Accordingly, in this paper the hygro-mechanical response of mock-ups of historical Dutch cabinet door panels made of oak wood is examined under several relative humidity variations. In specific, the mock-ups were subjected to (i) an instantaneous decrease of 40% relative humidity, (ii) eight successive, instantaneous drops of 5% relative humidity, and (iii) a varying relative humidity profile ranging between 35 and 71%. The shrinkage characteristics of mock-ups are translated to their damage susceptibility using an analytical hygro-mechanical bi-layer model. This model shows that restrained hygral shrinkage may originate from: (i) a difference in moisture content across the thickness direction of the panel, or (ii) a directional difference in the coefficient of hygroscopic expansions of structural components forming a coherent connection. The first type of shrinkage occurs in the outer regions of the panel thickness, while the second type of shrinkage takes place at the cleated ends. Further, by accounting for the age-dependency of the fracture strength of oak wood, a clear distinction can be made between the damage susceptibility of new door panels and historical door panels present in museum cabinets. The six main conclusions of the experimental study-conveniently summarized at the end of this paper-provide a scientific basis for the understanding of shrinkage cracks and dimensional changes observed on decorated oak wooden panels in historical Dutch cabinets, and thus may assist in advising museums on future sustainable preservation strategies and rational guidelines for indoor climate specifications.

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Section: Deformation Responsesupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Hygro-mechanical response of oak wood cabinet door panels under relative humidity fluctuations

et al. 2018

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“…The mechanical and dimensional response of wood to changes in RH have been studied extensively, both experimentally (Chomcharn and Skaar 1983;Schellen 2002;Bratasz et al 2010;Senni et al 2010;Caré et al 2012;Derome et al 2012;Gauvin et al 2014;Lanvermann, Wittel, and Niemz 2014) and numerically (Gloimüller et al 2012;Rafsanjani et al 2012;Saft and Kaliske 2013). Also, the consequences of unilateral exposure of a wooden board to a step change in RH have been studied for kiln-drying (Brandao and Perré 1996;Allegretti, Rémond, and Perré 2003;Allegretti and Ferrari 2007;Uetimane Junior et al 2010;Rémond et al 2013) and in a panel painting (Dionisi Vici, Mazzanti, and Uzielli 2006). Whereas the implications for panel paintings exposed to a sinusoidally fluctuating environment have been studied numerically (Rachwal et al 2012a(Rachwal et al , 2012b, experimental studies are scarce.…”

Section: Introductionmentioning

confidence: 99%

Relating relative humidity fluctuations to damage in oak panel paintings by a simple experiment

Arends

Pel

Schellen

et al. 2018

Studies in Conservation

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Panel paintings are essentially wooden boards painted on one side. Due to the vapor resistance of the paint layer, changing ambient conditions lead to exchange of moisture on only one surface. Subsequently, a non-uniform moisture content profile is formed across the thickness of the board. As a result, differential expansion causes the board to bend in case of no mechanical restriction, or it leads to a build-up of stresses inside the material if restrained. Experiments with oak boards sealed on one side and exposed to a change in the ambient relative humidity (RH) were performed. By scaling, the response of any board with different thickness can be predicted. Since the bending of the board can be described as a linear system behavior, the frequency response can be predicted based on the step response. In combination with critical strains for wood and gesso from the literature, this gives insight into allowable RH fluctuations in terms of frequency and amplitude for different board thicknesses.

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“…The DK is mounted at the backside of the panel painting and monitors the behaviour of the panel as a whole. The same research group also developed a monitoring cross beam (MCB) that measures cupping, swelling and shrinking, and constraint forces [19]. Strain measurements on wood are also performed with fibre Bragg grating sensors [13,20,21].…”

mentioning

confidence: 99%

Real-Time Wood Behaviour: The Use of Strain Gauges for Preventive Conservation Applications

Anaf

Cabal

Robbe

et al. 2020

Sensors

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Within the heritage field, the application of strain gauges on wood surfaces is a little-explored but inexpensive and effective method to analyse the environmental appropriateness of rooms for the wooden heritage collections they contain. This contribution proposes a wood sensor connected to a data logger to identify short moments with an elevated risk of harm. Two experiments were performed to obtain insights pertaining to the applicability of wood sensors to evaluate preservation conditions. (1) The representativeness of strain gauges on dummies was tested for their use in evaluating the preservation conditions of a range of wooden objects exposed to the same environment. For this, three situations were mimicked: a bare wood surface, a wood surface covered with a preparation layer, and a wood surface covered with a preparation and varnish layer. (2) The usability of strain gauges to monitor the wood behaviour in real-time measurements was tested with a monitoring campaign of almost two years in a church where a new heating system was installed. The results of both experiments are promising, and the authors encourage a broader application of strain gauges in the heritage field.

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Mechanical response of wooden boards subjected to humidity step variations: climatic chamber measurements and fitted mathematical models

Cited by 46 publications

References 1 publication

Hygro-mechanical response of oak wood cabinet door panels under relative humidity fluctuations

Hygro-mechanical response of oak wood cabinet door panels under relative humidity fluctuations

Relating relative humidity fluctuations to damage in oak panel paintings by a simple experiment

Real-Time Wood Behaviour: The Use of Strain Gauges for Preventive Conservation Applications

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