Advanced Art Authentication in Oil Paintings Using Precise 3D Morphological Analysis of Craquelure Patterns

The development of scientific technology for art authentication have elicited multidimensional evidence to distinguish forgeries from original artworks. Here, we analyzed three-dimensional morphology of cracks that contain information such as painting features of artworks using an optical coherence tomography (OCT). The forgeries were produced by an expert from the original oil paintings with cracks that occur as paint drying, canvas aging, and physical damage. The parameters such as shape, width, and depth were compared based on cross-sectional images of original and fake cracks. The shapes of original cracks were a rectangular and an inverted triangle, but fake cracks were a relatively simple inverted triangle. The original cracks were as deep as the thickness of the upper layer and mostly have ‘thin/deep' or 'wide/shallow'. The fake cracks were observed as 'thin/shallow' or 'wide/deep'. This study will improve the understanding of the crack characteristics and promote development of techniques for art authenticity.

Modeling the curing behavior of a toughened hot curing epoxide adhesive during the paint drying process

Lightweight body-in-white is often based on a mix of materials that causes problems in the production process. More specifically, the paint oven process after cathodic dip-coating can lead to damaged adhesive layers due to mismatches in thermal expansion of the materials. The understanding of the curing behavior of the structural adhesive cured in this oven process is of crucial interest to determine the damaging in numerical analyses. Therefore, the curing behavior of a one-component toughened hot curing structural adhesive is modeled using three model-based and a model-free approach as well as experimental data from differential scanning calorimetry. After the parameter identification of the models, the parameters are validated using an oven-process-like temperature profile to compare experimental and numerical data.

A numerical simulation of a line-type paint drying furnace

Purpose Paint drying is a very important process in an industry where shorter drying time for productivity and lower energy consumption for production cost are required while maintaining the product’s painting quality. In the present study, a drying process in a line-type paint drying furnace equipped with nozzles for hot air supply and moving conveyer belt to dry painted automotive parts is numerically simulated for the flow and heat transfer inside the furnace to evaluate the quality of the drying or baking at the end of the drying process in a production line. Design/methodology/approach A baking window for a specific paint is used for judging the local degree of baking (DOB) of the painted parts, which can be useful to identify under-baked or over-baked locations of the painted parts, and hence the quality of the baking process. Findings Numerical results of a time history of temperatures at two monitoring points on the painted parts were obtained and compared to the measured data in an actual furnace and showed good agreement. Three types of paints were considered in the present study and numerical results showed different drying characteristics. In addition to the original furnace nozzle configuration, two more furnace nozzle configurations with different numbers, direction and speed of hot air supply were simulated to improve the furnace’s drying performance. As a result, a newly suggested nozzle configuration with quick drying paint can give us a remarkable improvement in surface averaged DOB compared to the original nozzle configuration with original paint. Originality/value The present simulation technique and DOB methodology can be used for the optimal design of a drying furnace.

Influence of Pre-Strain and Simulated Paint-Bake on Mechanical Properties of High Strength Aluminum Alloy AA7020

In modern car bodies lightweight structures are used to achieve a reduction of energy consumption and CO2-emissions. One of the most important lightweight materials is aluminum and its alloys. Current state of the art in automotive industry is utilizing precipitation hardenable aluminum alloys of the 6000 series whereas the crash-relevant strength is achieved by artificial ageing during the paint drying process. Due to newly developed coatings which provide faster curing at lower temperatures, post-forming ageing of the 6xxx alloys to satisfactory strength levels becomes more difficult. The aim of this study is to investigate the feasibility of employing high strength aluminum alloys of the 7000 series in order to reduce artificial ageing time and temperature while keeping required strength. Within this contribution, the influence of pre-straining and subsequent heat treatment on mechanical properties will be presented.