Vibration Properties and Damage Behavior of Art in Transport

Works of art are historical documents that are worth preserving. Restorers play a key role in this effort. The value of artwork depends on many aspects, including its materiality. That's why it's important to secure and preserve this substance and system. External damaging influences, such as fluctuations in relative humidity, exposure to light and UV radiation, biological influences, and harmful gases, as well as mechanical factors, are among the most important threats to the preservation of works of art.

Transport in particular subjects paintings to mechanical loads caused by vibrations. The resulting motions can cause irreversible damage in the paint layer and the support, which must be avoided. One way to reduce damage is to design the mounting of paintings inside a transport crate in a targeted manner so that the paintings are decoupled from the motion of the crate as much as possible. Complete decoupling is technically impossible, which raises several research questions. Which crate motions lead to which paint layer motions? How are these motions distributed spatially? Which loads lead to which types of damage? Where do they occur, and after what duration? Is planned transport justifiable at all?

In order to clarify how paint layer motions arise from accelerations of the crate, and to derive a mathematical or numerical model from this process, we conduct measurements on real paintings and painting models. To eliminate the effects of climatic changes and damage, these measurements are taken in a climate chamber

As it is practically impossible to measure paint layer motions during transport, we also work on reproducing transport conditions in the laboratory as realistically as possible. We measure frame accelerations during real transport and reproduce them in the laboratory. This allows us to capture paint layer motions using measurement technology and compare them with the predictions of numerical models.

The use of numerical painting models allows paint layer motion to be described across the entire paint layer area. This is done using measured input data. Consequently, the load on the paint layer can also be determined. The complexity of the material constitution, the heterogeneity of the layering, and the associated complexity make this very difficult. Furthermore, the material parameters cannot be determined without destroying the material. Consequently, the validation of model parameters can only be accomplished through experimental investigations on well-defined specimens. In collaboration with Polytec GmbH, we have conducted optical strain measurements and are currently utilising these measurements to enhance the parameters of our numerical models.

Furthermore, we conduct long-duration vibration tests on specimens to identify which strains, after a given duration of loading, result in visible and invisible damage. The results depend on the specific material combination, for example the type of fabric, ground layer, paint type and paint layer build-up.