{"title":"Taivutuksesta ja väännöstä, osa II: Elementtimenetelmä","authors":"Jukka Aalto","doi":"10.23998/RM.95447","DOIUrl":"https://doi.org/10.23998/RM.95447","url":null,"abstract":"Artikkelin ensimmäisessä osassa [1] johdettiin kuormituksen alaiselle suoralle palkille yhdistetty taivutus- ja vääntöteoria. Se perustui neljää käyristymisfunktiota käyttäen muodostettuun yksinkertaiseen siirtymäotaksumaan. Tässä artikkelin toisessa osassa esitellään, kuinka tätä teoriaa voidaan soveltaa käytännön tehtäviin elementtimenetelmän tekniikoita hyväksi käyttäen. Tehtävä voidaan jakaa seuraaviin osiin: 1) käyristymisfunktioiden määrittä-minen, 2) poikkileikkaussuureiden määrittäminen, 3) palkkitehtävän ratkaiseminen ja 4) poikki-leikkauksen jännitysjakauman määrittäminen. Lopuksi esitetään laskentaesimerkki.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42092818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tero Frondelius, T. Kaarakka, Osmo Kaleva, Reijo Kouhia, Heikki Orelma, Joona Vaara
{"title":"Varmuuskerroin jännitysväsymisen kontinuumimallissa","authors":"Tero Frondelius, T. Kaarakka, Osmo Kaleva, Reijo Kouhia, Heikki Orelma, Joona Vaara","doi":"10.23998/RM.78149","DOIUrl":"https://doi.org/10.23998/RM.78149","url":null,"abstract":"The article examines the calculation of the safety factor for infinite lifetime in a stress-fatigue model based on continuum mechanics. The stress history can be either deterministic or stochastic. The calculation of the safety factor is reduced to finding the maximum value of the endurance function. In the case of a stochastic stress history, the values of the durability function also form a stochastic process with a maximum value probability distribution. The method is illustrated by simple one-dimensional and multi-axis industrial example calculations.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"54 1","pages":"21-29"},"PeriodicalIF":0.0,"publicationDate":"2021-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46030544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Abed, L. Korkiala-Tanttu, J. Forsman, K. Koivisto
{"title":"3D simulations of deep mixed columns under road embankment","authors":"A. Abed, L. Korkiala-Tanttu, J. Forsman, K. Koivisto","doi":"10.23998/rm.84590","DOIUrl":"https://doi.org/10.23998/rm.84590","url":null,"abstract":"When column stabilisation is meant to function as a ground improvement under an embankment, the design cases to be considered consist of overall stability, compression resistance of the column heads, arching of the embankment on the columns and settlements. This paper focuses on the compression resistance of the columns. The proper geotechnical design of deep mixed (deep stabilised) columns under road embankment requires good estimation of the stress-strain behaviour of the columns and the surrounding soil under the embankment and traffic loading. Earlier Finnish design approaches relied on an even traffic load of 10 kN/m2 on the road surface. The dimensioning methods for column stabilised soil are also based on the idea of an even traffic load. Due to Eurocode recommendations a more realistic scenario is introduced, which remarkably increases the magnitude of the traffic loading. After deriving suitable material properties and stiffness parameters for static and dynamic traffic loading, three-dimensional finite element calculations are performed to achieve better understanding of the mechanical interaction between the embankment, columns and soil under the new loading configuration. Even though more investigations are needed before delivering a final statement, the calculations show that, for the considered case in this paper, the new loading scenario has no relevant consequences on the design compared to the earlier design approach.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42524500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Laivojen pohjien likaantumisen vaikutus kulkuvastukseen Itämerellä: Chow-Liu-puulla täydennetyn Naiivi Bayes -mallin soveltaminen aluksen kulun analysointiin","authors":"Elias Altarriba","doi":"10.23998/RM.87314","DOIUrl":"https://doi.org/10.23998/RM.87314","url":null,"abstract":"The objective of the COMPLETE-project is to prevent spreading of harmful and invasive alien species in Baltic Sea region. Significant proliferation has happened with ballast waters but organisms are also being transported to new areas among underwater hull structures. In addition of alien species spreading issues, biofouling increases vessel hydrodynamic resistance affecting straightforward to fuel consumption and carbon dioxide emissions. At present day, this bio-contamination is deducted by regular cleanings of immersed hull structures during summer seasons. However, selection of cleaning intervals is based on experience. Also, the effect of cleaning is often perceived by crew, but normally there are no measurement-based knowledge on its effect on voyage of unique vessel. Nowadays ship systems provides increasingly data flow that can be stored automatically. Conclusion-making from big data requires appropriate tools specially limiting effects of many system mixers. This article explores usability of Chow-Liu-tree augmented Naive Bayes method for analyzing voyage data. The advantages of this method are computational efficiency and ability to produce reliable conclusions about causation relationships prevailing in the studied system, even if available data is quite limited.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"356-389"},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48814121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Principles of structured risk management in rock engineering","authors":"J. Spross","doi":"10.23998/RM.85711","DOIUrl":"https://doi.org/10.23998/RM.85711","url":null,"abstract":"This article, based on a keynote lecture given at the Finnish Rock Mechanics Day 2019, discusses how structured risk management can be implemented to rock engineering projects. The suggested procedure is based on ISO 31000 and a recently published methodology for practical implementation of the standard to geotechnical engineering projects. The main message is that structured risk management is a key tool to achieve high-quality rock engineering structures. A key component for many projects will be the use of the observational method to cost-effectively reduce the lack of knowledge of the ground conditions during construction of the facility.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"329-341"},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42543541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical simulation of laser welded joints: modern fatigue analysis methodology","authors":"R. Kokko, J. Vaara, T. Kuivaniemi, T. Frondelius","doi":"10.23998/RM.77613","DOIUrl":"https://doi.org/10.23998/RM.77613","url":null,"abstract":"Welding always induces discontinuities and imperfections in the structure that allows for potential fatigue cracks. Welding effects thermal strains, which yield to residual stresses of the structure that have a noticeable effect on the fatigue behaviour of the structure. Welding inexorably leads to microstructure and geometry changes in the welding region. Material internal changes, residual stresses and microstructural changes can be simulated numerically, and the simulation results can be used in cyclic loading analysis in FEA.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"342-355"},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41973212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jaakko Meuronen, A. Mäntylä, J. Vaara, J. Hintikka, J. Juoksukangas, A. Lehtovaara, T. Frondelius
{"title":"Fretting test rig with variable normal force","authors":"Jaakko Meuronen, A. Mäntylä, J. Vaara, J. Hintikka, J. Juoksukangas, A. Lehtovaara, T. Frondelius","doi":"10.23998/RM.83573","DOIUrl":"https://doi.org/10.23998/RM.83573","url":null,"abstract":"Fretting is small amplitude reciprocating sliding between surfaces, and it may quickly causes surface cracks, which can continue growing under cyclic loads, until the structure breaks entirely as a result of the fretting fatigue. Fretting can also produce hardened wear particles as a result of adhesive wear, which then accelerates abrasive wear. In this case, the community uses the term fretting wear. The design of heavily loaded contacts, susceptible to fretting, is a difficult task because there is no generally accepted design guide. More extensive fretting research is needed to create them. This paper introduces detailed design phases for a equipment (rig) for a variable normal force fretting test. Supporting high radial and normal forces such that there is minimal run-out between the specimens was the most significant design challenge. The combination of a hydrostatic radial bearing and elastic torque shaft was selected for the detail design phase based on FE-analyses, calculations, and overall evaluation. The frame of the test rig consists of the main frame, which supports mainly the normal force and two torque frames, which support torque cylinders. Many solutions, which were found to be working in the current \"ring-ring\" apparatus of Tampere University, could be utilized in the new test rig like the tapered connections of the specimens, the elastic rod of the torque lever, axial displacement plate, and contact pressure adjustment system. The designed test rig enables fretting tests with 0 Hz to 20 Hz cycle frequency so that normal and tangential force or displacement can be controlled independently of each other. The normal force cannot change from compression to tension dynamically, but the adhesive force of the contact can be measured by slowly increasing the tension force. The designed fretting test rig fulfills all essential requirements, which were set.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"308-328"},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43043094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Virtuaalisesta siirtymästä","authors":"E-M. Salonen, Mika Reivinen","doi":"10.23998/rm.85834","DOIUrl":"https://doi.org/10.23998/rm.85834","url":null,"abstract":"Artikkelissa tarkastellaan ainefaasien välisen faasipinnan käsittelyä virtuaalisen työn periaatteen avulla. Virtuaalisen siirtymän käsite vaatii tällöin tavanomaisesta poikkeavan tulkinnan.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47226818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hitsiliitoksen geometrian vaikutus väsymismitoituksessa","authors":"Lassi Keränen, Juhani Niskanen","doi":"10.23998/rm.83365","DOIUrl":"https://doi.org/10.23998/rm.83365","url":null,"abstract":"The effect of the welding heat input on the geometry of the butt welded joints and the effect of the geometry on the fatigue resistance were investigated in the study. The ultra-high strength structural steel with the yield strength of 700 MPa was welded with two different welding heat inputs. The geometries of the cross sections of the welded joints were imported to FE-software for the calculation of the fatigue notch factors. The calculated fatigue notch factors were compared with the factors from literature, and S-N-curves were determined with the aid of the fatigue notch factors. In addition, the effect of the element size on the notch factor and the effect of initial crack size on the fatigue life with the aid of fracture mechanics were investigated. It was observed that the geometry of the welded joint does not explain the changes of the fatigue resistance of the welded joint. At least the half of the decrease of the fatigue resistance compared with base material is due to other than geometry, in example microstructural changes caused by welding. If the S-N-curve is calculated only with a fatigue notch factor, the fatigue resistances are over-optimistic in comparison with literature and design guidelines. Utilizing the finite element method in design, the adequate dense element mesh must be used that the geometry of the structure and welded joint corresponds to the reality.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"281-303"},"PeriodicalIF":0.0,"publicationDate":"2020-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49464488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Overview of laser-welded thin-walled joints fatigue performance and a statistical method for defect analysis","authors":"R. Kokko, J. Vaara, T. Kuivaniemi, T. Frondelius","doi":"10.23998/rm.77612","DOIUrl":"https://doi.org/10.23998/rm.77612","url":null,"abstract":"Welding always has a deteriorating effect on fatigue strength in structures under dynamic loading. Weld joints induce discontinuity in structure geometry and the microstructure. Welding induced discontinuity, and defects allow for potential fatigue cracks that lead to the failure of welded parts or structures. The laser welding process differs from conventional arc welding in process and joint type. The most significant advantage in laser welding comes from the deep penetrating mode of welding, which also brings challenges to the soundness of the weld. The benefits of laser welding are most evident in the manufacture of sheet metal products such as sandwich panels. In literature, laser welding is generally dealt with by using different parts of the overall process without taking the fatigue point of view into account. In this article, the process of laser welding is discussed, while keeping fatigue strength in perspective. The fatigue data of laser welded joints is studied in order to find defect distribution that explains fatigue strength distribution in tests. The suitability of traditional fatigue assessment for laser welding is also discussed.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"259-280"},"PeriodicalIF":0.0,"publicationDate":"2020-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44008695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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