Journal of Structural Mechanics https://rakenteidenmekaniikka.journal.fi/ <p>Since 1968, the scope of Journal of Structural Mechanics has been theoretical, computational and experimental mechanics of solids and fluids as well as mathematics and applications related to these fields. Examples of possible topics are static and dynamic analyses of strength of structures, multibody dynamics, fluid mechanics, interaction of fluids and structures, design of structures and machines, structural optimization, functionality of structures in extreme conditions, smart machines and structures, vibration mechanics, contact mechanics, rotor dynamics, fracture mechanics and fatigue, thermomechanics, soil and rock mechanics, material technology, new materials, optimal control of dynamic systems, finite element methods and analysis, biomechanics, micromechanics, industrial and medical applications of mechanics, and teaching of mechanics and strength of materials. In addition to peer-reviewed scientific articles, the journal publishes also short letters containing opinions or critique on articles published in the journal or short letters describing a technical method or a solution having interest in the field of the journal. The length of these letters should not exceed six pages.</p> fi-FI jarkko.niiranen@aalto.fi (Jarkko Niiranen) jarkko.niiranen@aalto.fi (Jarkko Niiranen) Mon, 23 Jun 2025 23:47:36 +0300 OJS 3.2.1.4 http://blogs.law.harvard.edu/tech/rss 60 Preface https://rakenteidenmekaniikka.journal.fi/article/view/163015 Jarkko Niiranen Copyright (c) 2025 Jarkko Niiranen https://creativecommons.org/licenses/by/4.0 https://rakenteidenmekaniikka.journal.fi/article/view/163015 Mon, 23 Jun 2025 00:00:00 +0300 Design of a non-linear wire-rope tuned mass damper – linearized model-based approach https://rakenteidenmekaniikka.journal.fi/article/view/152288 <p>Wire rope springs are used in tuned mass damper applications due to their inherent energy dissipation properties, low cost, thermal stability and mechanical robustness. The dynamics of the wire rope springs are characterized by the relative sliding of the strands inside the wire ropes. Damping of the wire rope consists of the friction loss between the wire strands and structural damping under mechanical deformations. Moreover, the relative sliding alters the effective stiffness of the structure. These properties are non-linear and depend on the vibration amplitude. Modeling these non-linear dynamics has proven difficult, and no clear standard approach for design exist. In this paper, an amplitude based linearization framework is used to model the system dynamics for wire rope based tuned mass damper. The vibration suppression performance of the wire-rope tuned mass damper is compared to a linear tuned mass damper with similar mass ratio. The performance of the two dampers are compared for a system with multiple degrees of freedom, and the possible mistuning of the dampers is also considered. The results show that wire rope based tune mass damper, in comparison to a conventional linear tuned-mass damper, can suppress vibrations with a wider frequency band and under varying natural frequencies.</p> Samuli Rytömaa, Sampo Laine, Raine Viitala Copyright (c) 2025 Samuli Rytömaa, Sampo Laine, Raine Viitala https://creativecommons.org/licenses/by/4.0 https://rakenteidenmekaniikka.journal.fi/article/view/152288 Mon, 23 Jun 2025 00:00:00 +0300 Finite element methods for elastic contact: penalty and Nitsche https://rakenteidenmekaniikka.journal.fi/article/view/152348 <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>We consider two methods for treating elastic contact problems with the finite element method; the penalty method and Nitsche's method. For the penalty method, we discuss how the penalty parameter should be chosen. Both the theoretical analysis and numerical examples show that an optimal convergence rate cannot be achieved. The method is contrasted to that of Nitsche's method which is optimally convergent. We also give the derivation of Nitsche's method by a very simple consistency correction of the penalty method.</p> </div> </div> </div> Tom Gustafsson, Rolf Stenberg Copyright (c) 2025 Tom Gustafsson, Rolf Stenberg https://creativecommons.org/licenses/by/4.0 https://rakenteidenmekaniikka.journal.fi/article/view/152348 Mon, 23 Jun 2025 00:00:00 +0300 Simulation of hydrogen-induced failure in high strength steel https://rakenteidenmekaniikka.journal.fi/article/view/152469 <p>We present a coupled chemo-mechanical and fracture mechanics-based model capable of predicting the onset of hydrogen-induced macroscopic crack growth as a function of material, loading and environmental variables. The model is implemented using the commercial multi-physics simulation package COMSOL and solved as a coupled deformation–diffusion problem to define a fracture criterion as a function of residual and externally applied loads and hydrogen concentration. The local hydrogen-induced material damage is approximated by a parametric dependency of local fracture resistance on hydrogen concentration. As an example, we demonstrate the ductile-brittle transition of the failure pattern of a double-notch specimen under tension w/o and w/ hydrogen loading.</p> Stefan Lampenscherf, Gia Khanh Pham Copyright (c) 2025 Stefan Lampenscherf, Gia Khanh Pham https://creativecommons.org/licenses/by/4.0 https://rakenteidenmekaniikka.journal.fi/article/view/152469 Mon, 23 Jun 2025 00:00:00 +0300 Computer vision framework for crack detection and estimation of air leakage through the straight-through cracks in buildings envelopes https://rakenteidenmekaniikka.journal.fi/article/view/152481 <p>Over time, buildings inevitably experience physical and functional deterioration. Regular and accurate inspections are essential to ensure safety and functionality, helping to avoid hazardous and uncomfortable conditions. Cracks, a common indicator of structural distress, also facilitate air infiltration due to pressure differences between the interior and exterior. The precise and efficient detection of cracks, along with the estimation of air infiltration through these cracks, is therefore critical for civil engineering applications that aim to reduce energy consumption and enhance indoor air quality. This paper introduces a novel image processing framework for automatic detection of cracks in building envelopes, coupled with the measurement of indoor and outdoor air parameters, which could be used to assess crack size and to estimate air infiltration rates by using heat transfer and fluid mechanics formulas. A computer vision-based system for automatic crack detection is first developed by using the Python OpenCV library through binarization, Otsu's thresholding and Canny operator; geometric quantification of the cracks is then obtained via skeletonization, and the resulting morphological characteristics of the cracks are finally used to estimate airflow by using common fluid mechanics formulas.</p> Maliheh Jahanbakhsh, Andrea Ferrantelli Copyright (c) 2025 Maliheh Jahabakhsh, Andrea Ferrantelli https://creativecommons.org/licenses/by/4.0 https://rakenteidenmekaniikka.journal.fi/article/view/152481 Mon, 23 Jun 2025 00:00:00 +0300 Indentation hardness of 3D-printed metals https://rakenteidenmekaniikka.journal.fi/article/view/148552 <p>Additive manufacturing is typically used for rapid prototyping and the production of small to medium quantities of complex parts. The quality of 3D-printed metallic parts depends on the printing process parameters and material behaviour. In order to characterize the mechanical properties of materials, the nearly non-destructive micro-indentation hardness testing of additively manufactured steel and aluminium alloy using Laser Powder Bed Fusion technology was investigated in this study. The micro-hardness and modulus of elasticity of hot work tool steel AISI H13 (1.2344) were evaluated to study the influence of printing parameters, such as laser power and laser scanning speed. While no pile-up or sink-in effects were detected in the steel samples, the pile-up effect was observed during the hardness measurement of the aluminum alloy AlMg1Si AA-6061. Since the pile-up effect leads to an overestimation of the measured hardness, a correction factor was applied to account for this deviation, resulting in an adjusted value approximately 7% lower than the initially measured hardness for the aluminum alloy. In addition, the statistical reliability of the measured hardness properties of the 3D-printed metals was evaluated using the Weibull distribution. It was demonstrated that the indentation test is highly suitable for analyzing small additively manufactured samples with relatively little effort while delivering high statistical reliability and providing meaningful insights into the mechanical properties of the materials, such as micro-hardness and indentation modulus.</p> Gia Khanh Pham, Ruth Domes, Ümit Mavis, Johannes Ernstberger, Christian Seidel, Constanze Eulenkamp, Christine Hausner-Henzel, Anh Son Nguyen, Gia Vu Pham Copyright (c) 2025 Gia Khanh Pham, Ruth Domes, Ümit Mavis, Johannes Ernstberger, Christian Seidel, Constanze Eulenkamp, Christine Hausner-Henzel, Anh Son Nguyen, Gia Vu Pham https://creativecommons.org/licenses/by/4.0 https://rakenteidenmekaniikka.journal.fi/article/view/148552 Mon, 23 Jun 2025 00:00:00 +0300