The impact dynamics and drying of paint films sprayed on steel were experimentally investigated. The rupture of sprayed liquid films was first photographed on different substrates. The critical film thickness, below which a film would break, was observed to increase with increasing advancing liquid-solid contact angle, and was unaffected by liquid viscosity for a given substrate. For viscous paint, it was observed that there is no rupture or splashing from a paint droplet impacting a solid substrate or another paint drop or film. For paint films drying at room temperature, mass fluxes were measured and correlated with a simple analytical model based on transient diffusion, and showed good agreement. The mass flux of sprayed paint films decreased slightly with time, and the volatile concentration decreased appreciably. For sprayed paint films cured with heat, there is a minimum stand-time in order to cure a film without any entrapped bubbles.

The impact dynamics and drying of paint films sprayed on steel were experimentally investigated. The rupture of sprayed liquid films was first photographed on different substrates. The critical film thickness, below which a film would break, was observed to increase with increasing advancing liquid-solid contact angle, and was unaffected by liquid viscosity for a given substrate. For viscous paint, it was observed that there is no rupture or splashing from a paint droplet impacting a solid substrate or another paint drop or film. For paint films drying at room temperature, mass fluxes were measured and correlated with a simple analytical model based on transient diffusion, and showed good agreement. The mass flux of sprayed paint films decreased slightly with time, and the volatile concentration decreased appreciably. For sprayed paint films cured with heat, there is a minimum stand-time in order to cure a film without any entrapped bubbles.

In dieser Arbeit wird die Berechenbarkeit des Deformationsverhaltens von Aluminiumaußenhautbauteilen in einem für die Automobilindustrie typischen Lacktrocknungsprozess um den irreversiblen Kriecheffekt erweitert. Untersucht wird dabei die in Europa oft für Außenhautbauteile eingesetzte Legierung AA6016 mit Hilfe von Zug- und Biegetests, aus denen ein geeignetes Werkstoffmodell für die numerische Simulation abgeleitet wird. Dabei wird auch der Einfluss des Umformgrades im Blechbauteil aus dem Herstellprozess untersucht und bewertet. Die seriennahe Validierung des Werkstoffmodells findet anhand einer eigens ausgelegten Baugruppe statt, die nach dem Wärmeprozess optisch sichtbare Formabweichungen aufweist. Mittels optischer Messungen wird die Baugruppe dabei vor, im und nach dem Wärmeprozess analysiert und die berechneten Formänderungen validiert. Im Ergebnis kann mit dem Werkstoffmodell die Auswirkung thermisch induzierter Spannungen unterhalb der klassischen Streckgrenze auf die Formänderung von Aluminiumblech in der frühen Produktentwicklungsphase prognostiziert werden. / In this work, the computability of the deformation behaviour of aluminium car body panels in a typical automotive paint drying process is enhanced by the irreversible creep effect. The alloy AA6016, which is often used in Europe for aluminium car body panels, is examined with the aid of tensile and bending tests from which a suitable material model for numerical simulation is derived. The influence of the plastic deformation in the sheet metal component due to the manufacturing process is also examined and evaluated. The near-series validation of the material model takes place on the basis of a specially designed assembly which shows optically visible shape deviations after the heating process. Using optical measurements, the assembly is analyzed before, during and after the heating process and the calculated shape changes are validated. As a result, the material model can be used to predict the effect of thermally induced stresses below the classic yield strength on the deformation of aluminium sheet in the early product development phase.