## 8 Discussions and Conclusions
### Discussions on the Reviewed Studies
In-depth knowledge of the hygro-mechanical behaviour of wooden heritage requires non-invasive continuous monitoring of materials' deformation and environmental parameters. This is a limitation in the absence of automated measuring and recording procedures. In the monitoring of artworks in an open environment, a further challenge is represented by connection problems of cables and data logging systems. To deal with this issue, ad hoc and advanced equipment have been developed for monitoring buildings and small artefacts [129; 151; 152]. The use of NDT does not always allow it to encompass all involved phenomena, and this can lead to an oversimplification of the problem and an overestimation of some parameters, such as moisture [101]. More invasive techniques are then employed and allow for the ensuing capture of important irreversible deformation components, i.e., viscoelasticity and mechanosorption. In the study of musical instruments [130] and building elements [90] these deformations are fundamental for understanding the behaviour of wood. They naturally undergo cyclical moisture content changes and mechanical load during their use. Among the collected studies, the main investigations have been conducted to assess musical instruments. In this context, the work of [PERSON] et al. [87], where dead load tests are employed to study the mechanosorptive effect in a valuable wood violin, is highly relevant. To assess irreversible deformations while avoiding experiments on real artefacts, simulation tools are employed. Mathematical modelling and numerical simulations, as described in Section 6.2, allow for the study of moisture-induced stress and strain by multiphysics models. During the last decade, these models were developed in advanced FEM software. As demonstrated by [PERSON] et al. [109], a more realistic predictive tool is developed by integrating outdoor and indoor climate data in the model, particularly in historical buildings. It has been shown that combining building dynamic simulation and simulation at the material level allows for a better assessment of actual or potential risks from damages due to environmental changes and mechanical loads. The reliability of these models depends on many simplifications and assumptions, as well as on materials' parameters. Parameters which describe material properties and wood are used as input variables to validate the models. After careful assessment, the main studied parameters in the field were summarised in Table 1. The data extracted from several articles have been cross-referenced in order to provide an analysis on the use of these parameters, both as input in the mathematical models and to validate them. Often, the level of detail of some studies does not allow for a clear overview. Although this is outside the scope of many research works, a clear design of how experiments and mathematical models interact is important. For these reasons, in Figure 18, the correlation between experimental methods and numerical modelling is depicted by means of a cognitive scheme. As highlighted so far, the validation and parameter calculation is often carried out on duplicates of heritage objects. As suggested by some authors, even when experiments on real artefacts are not possible, it is not recommended to take these numbers from the literature to avoid unreliable results [109] The same artefacts or building elements may differ from one another in many characteristics. Therefore, it is also important to characterise the hygro-mechanical behaviour of all elements of an artefact. Instead, to simplify complex models, important layers of wooden heritage are often omitted. In most cases, adhesives and the system of coatings are not investigated, and they are discarded in numerical models. In line with [120,153], an accurate hygro-mechanical analysis should also test and analyse them.