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This paper presents a simple experimental validation of a method for finding optimal application patterns in adhesive bonding, as previously introduced by Flaig et al. (2023). The study uses two examples to demonstrate that the patterns found in theory effectively fill the target gaps after pressing in practice. The results confirm that the identified application patterns fill the target gaps almost perfectly, ensuring excellent joint integrity after the pressing process. In particular, the applicability of the star pattern to fill square gaps is experimentally validated. In addition, the method of creating a rectangle by pressing a cut star connected by a straight beam is also effective. While the theoretical results in Flaig et al. (2023) were already promising, this research now provides experimental evidence of their practical applicability. [ABSTRACT FROM AUTHOR]

In the manufacturing industry, the process of applying adhesive to join two substrates can be challenging. It requires precise placement of adhesive so that it is distributed in the desired pattern, ensuring a strong bond between the substrates. Overfilling is a common practice to ensure that the bond is not underfilled after the substrates are pressed together. However, this approach leads to unnecessary adhesive waste and can result in additional cleaning work. To address these issues, an optimization algorithm has been developed that can compute an initial adhesive pattern to flow into any desired geometry. The algorithm is based on a transient squeeze flow simulation, which iteratively removes fluid material as it flows out of the target bond domain. For example, to obtain a square bond geometry after a parallel squeezing process, the adhesive needs to be initially applied in a star shape. However, the algorithm is highly adaptable and can be used for many desired bond geometries as shown in this paper. The results are independent of the mesh resolution and fluid flow law, thus eliminating the need for complex rheological fluid characterization. The algorithm requires only two input parameters, namely the target bond geometry and the degree of compression. This highly simplifies the adaption of the proposed optimization method for manufacturers, and their design requirements can be considered with ease. The results are reliable and consistent despite the simulation's complexity. Overall, this new optimization methodology represents a significant advance in adhesive application technology, eliminating the need of overfilling and thus making the manufacturing process more efficient, sustainable and cost-effective. [ABSTRACT FROM AUTHOR]

The highly automated world of manufacturing industry offers new possibilities for the application of adhesives which are not fully utilized yet. In addition to the classical static stress and strength related topics, a more global view on adhesive bonding is needed. This includes the consideration of adhesive flow during application and joining of the substrates with all the information about initial application pattern and the resulting adhesive distribution contained after joining, and thus benefit from the modern manufacturing possibilities. To do so, research which addresses this issue is needed in the first place to elaborate innovative approaches on how to design and develop adhesive application pattern which minimize adhesive spillage and waste while achieving a bond without any air enclosures or other imperfections. This paper systematically investigates different phenomena which can occur during the joining process, such as the formation of air pockets and how they behave once formed. Furthermore, optimized application pattern and the merging behaviour of different flow fronts are considered. In total, four different adhesive application patterns were investigated experimentally and analysed using Particle Image Velocimetry. The investigations were complemented by a numerical simulation of the corresponding squeeze flow experiments — which achieved a high level of agreement. It was found that during the joining process, existing air pockets can reform due to the phenomenon of viscous fingering and subsequently cure into flat cavities, which are more critical in terms of bonding strength than spherical ones. [ABSTRACT FROM AUTHOR]

• A joining concept combining adhesive bonding, welding and bolting is presented. • Climate data from platforms in the North and Baltic Seas are obtained and evaluated. • A real offshore jacket is numerically modelled in order to determine mechanical stresses. • Adhesives meeting the requirements are analyzed mechanically and thermo-mechanically. • The relationship between stress, temperature and adhesive properties is highlighted. Due to the advantageous wind conditions, many new structures are planned offshore. The construction of offshore structures with ever increasing sizes requires new concepts to cope with the particular requirements thereof. One often overlooked possibility is adhesive bonding as a structural joining method, which upholds significant optimisation potential. This paper, the first in a series of two, illustrates the potential of adhesive bonding on the widely used jacket structure. For that, the structural concept is adapted towards ease of manufacturing, hybrid joints are defined, adhesives are selected according to requirements resulting from structural and climatic constraints, structural verifications performed, and the validation therefor presented in preliminary small-scale tests—which will be upscaled in the second part of this series. This paper thus serves as a roadmap for practitioners, and outlines the various steps to evaluate the potential of adhesive bonding in complex structures. [ABSTRACT FROM AUTHOR]