Research on the bond performance of CFRP-strengthened steel have been done for the past years, but it has mainly focused on lower grades of steel. The performance of the bond between ultra-high modulus (UHM) CFRP and high/ultra-high strength steel (HSS/UHSS) is investigated in this paper. A series of experiments have been conducted, with single/double side-strengthened (SSS/DSS) HSS/UHSS with CFRP laminates using Araldite adhesive. It was found that strengthening up to the ultimate strength of the DSS specimens is feasible. However, debonding happens at the ultimate strength of SSS specimens.
{"title":"Bonded CFRP to high strength steels","authors":"M. Amraei, Lin Zong, A. Ahola, T. Björk","doi":"10.23998/rm.76267","DOIUrl":"https://doi.org/10.23998/rm.76267","url":null,"abstract":"Research on the bond performance of CFRP-strengthened steel have been done for the past years, but it has mainly focused on lower grades of steel. The performance of the bond between ultra-high modulus (UHM) CFRP and high/ultra-high strength steel (HSS/UHSS) is investigated in this paper. A series of experiments have been conducted, with single/double side-strengthened (SSS/DSS) HSS/UHSS with CFRP laminates using Araldite adhesive. It was found that strengthening up to the ultimate strength of the DSS specimens is feasible. However, debonding happens at the ultimate strength of SSS specimens.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46329068","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}
L. Siivonen, Miika Paloniitty, M. Linjama, A. Hynnä, S. Launis
Vacuum brazed steel-copper laminate could be used in high-pressure hydraulic manifolds in order to reduce size, weight and allow use of complex designs. The durability of such material is unknown. Samples were manufactured and static and dynamic tests were conducted. Results showed reduced material performance due to heat treatment. A hydraulic test manifold was manufactured and a long-term pressure load test was conducted. The material showed surprisingly good durability and pressure hull did not break in tests. A microscopic study was performed and only solidified copper in the corners had micro cracks after 10 million test cycles.
{"title":"Suitability of laminated steel-copper structure for high-pressure hydraulic manifolds","authors":"L. Siivonen, Miika Paloniitty, M. Linjama, A. Hynnä, S. Launis","doi":"10.23998/rm.76405","DOIUrl":"https://doi.org/10.23998/rm.76405","url":null,"abstract":"Vacuum brazed steel-copper laminate could be used in high-pressure hydraulic manifolds in order to reduce size, weight and allow use of complex designs. The durability of such material is unknown. Samples were manufactured and static and dynamic tests were conducted. Results showed reduced material performance due to heat treatment. A hydraulic test manifold was manufactured and a long-term pressure load test was conducted. The material showed surprisingly good durability and pressure hull did not break in tests. A microscopic study was performed and only solidified copper in the corners had micro cracks after 10 million test cycles.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"52 1","pages":"244-250"},"PeriodicalIF":0.0,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68797425","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}
This article briefly describes a new programming language Julia and a new innovative Finite Element Method (FEM) solver JuliaFEM. We selected an easy to understand example of a linear elasticity problem as a method for this introduction. We go through the example step by step and provide a detailed explanation of the different phases of the solution steps. The main result presented here demonstrates the scripting possibilities of JuliaFEM, both pre- and post-processing.
{"title":"Introduction to JuliaFEM, an open source FEM solver","authors":"Jukka Aho, Antti-Jussi Vuotikka, T. Frondelius","doi":"10.23998/RM.75103","DOIUrl":"https://doi.org/10.23998/RM.75103","url":null,"abstract":"This article briefly describes a new programming language Julia and a new innovative Finite Element Method (FEM) solver JuliaFEM. We selected an easy to understand example of a linear elasticity problem as a method for this introduction. We go through the example step by step and provide a detailed explanation of the different phases of the solution steps. The main result presented here demonstrates the scripting possibilities of JuliaFEM, both pre- and post-processing.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47076940","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}
The sensitized principle of virtual work is applied to modify the stiffness matrix of the ordinary four-node rectangular element by sensitizing terms. The sensitizing parameter values are determined by the single-element strain energy test. The reference solutions used are of bending mode types and their application removes the so-called parasitic shear behavior. A stiffness matrix of good quality is obtained corresponding exactly to an earlier formulation using incompatible modes.
{"title":"A modified four-node rectangular element","authors":"J. Freund, Eero-Matti Salonen","doi":"10.23998/rm.75555","DOIUrl":"https://doi.org/10.23998/rm.75555","url":null,"abstract":"The sensitized principle of virtual work is applied to modify the stiffness matrix of the ordinary four-node rectangular element by sensitizing terms. The sensitizing parameter values are determined by the single-element strain energy test. The reference solutions used are of bending mode types and their application removes the so-called parasitic shear behavior. A stiffness matrix of good quality is obtained corresponding exactly to an earlier formulation using incompatible modes.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48842201","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}
Marja Rapo, J. Vaara, Jukka Aho, T. Kuivaniemi, Niclas Liljenfeldt, Antti Vuohijoki, T. Frondelius
An optimization routine was applied to high pressure fuel pipes to avoid resonance in a heavily vibrating environment. The optimization process and also the natural frequency calculations in every iteration were completely performed with the high-level programming language Julia; the optimization process was performed with the JuMP optimization environment, and the frequencies where calculated with JuliaFEM finite element method solver platform. The benefit of this kind of embedded implementation is a quick response which yields a pleasant development environment to focus on the essential—the choice of the optimization strategy.
{"title":"Pipe route optimization to avoid undesired vibration by using JuliaFEM","authors":"Marja Rapo, J. Vaara, Jukka Aho, T. Kuivaniemi, Niclas Liljenfeldt, Antti Vuohijoki, T. Frondelius","doi":"10.23998/rm.76259","DOIUrl":"https://doi.org/10.23998/rm.76259","url":null,"abstract":"An optimization routine was applied to high pressure fuel pipes to avoid resonance in a heavily vibrating environment. The optimization process and also the natural frequency calculations in every iteration were completely performed with the high-level programming language Julia; the optimization process was performed with the JuMP optimization environment, and the frequencies where calculated with JuliaFEM finite element method solver platform. The benefit of this kind of embedded implementation is a quick response which yields a pleasant development environment to focus on the essential—the choice of the optimization strategy.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42064932","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}
Jukka Aho, V. Jämsä, T. Kuivaniemi, Niclas Liljenfeldt, T. Frondelius
This article describes implementations of beam elements to JuliaFEM. The theory is briefly introduced, and the usage of beam elements is introduced with a usage example that involves a natural frequency calculation of a formula race car frame. The calculation results were compared to results from a commercial program, and their consistency is excellent.
{"title":"JuliaFEM beam element implementation","authors":"Jukka Aho, V. Jämsä, T. Kuivaniemi, Niclas Liljenfeldt, T. Frondelius","doi":"10.23998/rm.76193","DOIUrl":"https://doi.org/10.23998/rm.76193","url":null,"abstract":"This article describes implementations of beam elements to JuliaFEM. The theory is briefly introduced, and the usage of beam elements is introduced with a usage example that involves a natural frequency calculation of a formula race car frame. The calculation results were compared to results from a commercial program, and their consistency is excellent.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49090986","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 material containing spherical microvoids with a Hookean matrix response was shown to take the appearance usually applied in continuum damage mechanics. However, the commonly used variable damage D was replaced with the void volume fraction f , which has a clear physical meaning, and the elastic strain tensor Bold {ε}^e with the damage-elastic strain tensor Bold {ε}^{de}. The postulate of strain equivalence with the effective stress concept was reformulated and applied to a case where the response of the matrix obeys Hooke’s law. In contrast to many other studies, in the derived relation between the effective stress tensor Bold {Tilde{σ}} and the stress tensor Bold {σ}, the tensor Bold {Tilde{σ}} is symmetric. A uniaxial bar model was introduce for clarifying the derived results. Other candidates for damage were demonstrated by studying the effect of carbide coarsening on creep rate.
{"title":"On continuum damage mechanics","authors":"K. Santaoja","doi":"10.23998/rm.76025","DOIUrl":"https://doi.org/10.23998/rm.76025","url":null,"abstract":"A material containing spherical microvoids with a Hookean matrix response was shown to take the appearance usually applied in continuum damage mechanics. However, the commonly used variable damage D was replaced with the void volume fraction f , which has a clear physical meaning, and the elastic strain tensor Bold {ε}^e with the damage-elastic strain tensor Bold {ε}^{de}. The postulate of strain equivalence with the effective stress concept was reformulated and applied to a case where the response of the matrix obeys Hooke’s law. In contrast to many other studies, in the derived relation between the effective stress tensor Bold {Tilde{σ}} and the stress tensor Bold {σ}, the tensor Bold {Tilde{σ}} is symmetric. A uniaxial bar model was introduce for clarifying the derived results. Other candidates for damage were demonstrated by studying the effect of carbide coarsening on creep rate.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44540517","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}
T. Saksala, Martina Pressacco, S. Holopainen, R. Kouhia
This article gives a computational continuum mechanics answer to a question of how much heat is generated, in terms of temperature rise, during controlled shear band formation in a rock like material. This problem is treated as adiabatic heating due to mechanical dissipation at the material point level. Assuming that only the compressive strength of the rock is temperature dependent, the coupled system of the constitutive equations and the adiabatic heat equation can be solved as a second order polynomial equation for the viscoplastic multiplier at an integration point. A Mohr-Coulomb viscoplastic model with linear softening is employed for rock material description. Numerical simulations of a 2D strip under uniaxial compression at strain rates up to 10 1/s show that the temperature rise in a rock like material with a compressive strength of 100 MPa is less than two degrees.
{"title":"Numerical modelling of heat generation during shear band formation in rock","authors":"T. Saksala, Martina Pressacco, S. Holopainen, R. Kouhia","doi":"10.23998/RM.75287","DOIUrl":"https://doi.org/10.23998/RM.75287","url":null,"abstract":"This article gives a computational continuum mechanics answer to a question of how much heat is generated, in terms of temperature rise, during controlled shear band formation in a rock like material. This problem is treated as adiabatic heating due to mechanical dissipation at the material point level. Assuming that only the compressive strength of the rock is temperature dependent, the coupled system of the constitutive equations and the adiabatic heat equation can be solved as a second order polynomial equation for the viscoplastic multiplier at an integration point. A Mohr-Coulomb viscoplastic model with linear softening is employed for rock material description. Numerical simulations of a 2D strip under uniaxial compression at strain rates up to 10 1/s show that the temperature rise in a rock like material with a compressive strength of 100 MPa is less than two degrees.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42226621","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}
Artikkelissa esitetään moniaksiaalisen väsyttävän kuormituksen aikahistorian sykliluokitusta Wang–Brown-menettelyllä ja sen soveltamista ääriarvopistesuodatettuun dataan. Perinteisen yksiaksiaalisen kuormitushistorian sykliluokitus aloitetaan datan ääriarvopistesuodattamisesta eli ennen sykliluokitusta datasta poistetaan kaikki muu paitsi ääriarvopisteet. Moniaksiaalisen kuormituksen tapauksessa pelkän ääriarvopistedatan käyttö voi johtaa ongelmatilanteisiin Wang–Brown-sykliluokituksen käytön yhteydessä. Potentiaaliset ongelmatilanteet eivät ole vain teoreettisesti mahdollisia erikoistapauksia, vaan voivat olla esimerkiksi pyörivien koneenosien hyvin tyypillisiä kuormituksia. Työssä on esitetty ääriarvopistedatan Wang–Brown-sykliluokituksen käyttöön liittyvät potentiaaliset ongelmatilanteet sekä mahdolliset keinot niiden välttämiseksi.
{"title":"Moniaksiaalisen kuormitushistorian ääriarvopistedatan sykliluokitus Wang-Brown-menetelmän avulla","authors":"Alexei Yanchukovich, Antti Ahola, Timo Björk","doi":"10.23998/RM.75618","DOIUrl":"https://doi.org/10.23998/RM.75618","url":null,"abstract":"Artikkelissa esitetään moniaksiaalisen väsyttävän kuormituksen aikahistorian sykliluokitusta Wang–Brown-menettelyllä ja sen soveltamista ääriarvopistesuodatettuun dataan. Perinteisen yksiaksiaalisen kuormitushistorian sykliluokitus aloitetaan datan ääriarvopistesuodattamisesta eli ennen sykliluokitusta datasta poistetaan kaikki muu paitsi ääriarvopisteet. Moniaksiaalisen kuormituksen tapauksessa pelkän ääriarvopistedatan käyttö voi johtaa ongelmatilanteisiin Wang–Brown-sykliluokituksen käytön yhteydessä. Potentiaaliset ongelmatilanteet eivät ole vain teoreettisesti mahdollisia erikoistapauksia, vaan voivat olla esimerkiksi pyörivien koneenosien hyvin tyypillisiä kuormituksia. Työssä on esitetty ääriarvopistedatan Wang–Brown-sykliluokituksen käyttöön liittyvät potentiaaliset ongelmatilanteet sekä mahdolliset keinot niiden välttämiseksi.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49336373","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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