1. Influence of surface preparation and surface topography on tensile shear strength of polyurethane adhesively bonded beech wood single-lap joints : a finite element method approachLuka Naumovski, Martin Capuder, Jakub Michal Sandak, Boris Azinović, 2025, original scientific article Abstract: In this study, the mechanical properties of bonded single-lap joints are analysed by tensile lap shear tests on beech wood. A one-component polyurethane adhesive was used, and three different methods of surface preparation were applied: planing, sanding along the grain, and sanding perpendicular to the grain. Prior to bonding, the wooden lamellae underwent laser scanning to obtain surface profiles, which were then analysed for surface roughness. Scanned surface topographies with their features were integrated into the finite element analysis (FEA) software COMSOL Multiphysics to simulate the lap shear bonding area for different surface profiles and roughness. The FEA model implements linear material models, which represent the adherend and thin adhesive layer, combined with a modified local cohesive zone model for the adhesive bond interfacial forces. The experimental tests were conducted in a dry environment, where a higher surface roughness achieved by sanding correlated with a higher tensile shear strength. This increased surface roughness was attributed to the enhanced mechanical interlocking mechanism. This finding aligns with the FE analysis, which showed that increased surface roughness, micropillars and indentations, led to variations in stress concentration and distribution compared to a smooth surface bond.
Keywords: beech wood, mechanical interlocking, surface modification, polyurethane, finite element modeling
Published in DiRROS: 11.08.2025; Views: 464; Downloads: 212
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2. Extending BIM for air quality monitoringMichael Nicolas Mrissa, Jan Vcelak, László Hajdu, Balázs Dávid, Miklós Ferenz Krész, Jakub Michal Sandak, Anna Malgorzata Sandak, Rok Kanduti, Monika Varkonji, Anja Jutraž, Katja Malovrh Rebec, 2020, published scientific conference contribution Abstract: As we spend more than 90% of our time inside buildings, indoor environmental quality is a major concern for healthy living. Recent studies show that almost 80% of people in European countries and the United States suffer from SBS (Sick Building Syndrome), which affects physical health, productivity and psychological well-being. In this context, environmental quality monitoring provides stakeholders with crucial information about indoor living conditions, thus facilitating building management along its lifecycle, from design, construction and commissioning to usage, maintenance and end-of-life. However, currently available modelling tools for building management remain limited to static models and lack integration capacities to efficiently exploit environmental quality monitoring data. In order to overcome these limitations, we designed and implemented a generic software architecture that relies on accessible Building Information Model (BIM) attributes to add a dynamic layer that integrates environmental quality data coming from deployed sensors. Merging sensor data with BIM allows creation of a digital twin for the monitored building where live information about environmental quality enables evaluation through numerical simulation. Our solution allows accessing and displaying live sensor data, thus providing advanced functionality to the end-user and other systems in the building. In order to preserve genericity and separation of concerns, our solution stores sensor data in a separate database available through an application programming interface (API), which decouples BIM models from sensor data. Our proof-of-concept experiments were conducted with a cultural heritage building located in Bled, Slovenia. We demonstrated that it is possible to display live information regarding environmental quality (temperature, relative humidity, CO2, particle matter, light) using Revit as an example, thus enabling end-users to follow the conditions of their living environment and take appropriate measures to improve its quality
Keywords: Building Information Model, internet of things, environmental quality monitoring, healthy living
Published in DiRROS: 19.01.2024; Views: 1367; Downloads: 673
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