This paper opens up the history of structural analysis and dynamics simulations of Wärtsilä engines. It cites already published articles and theses with some backgrounds information. It also discusses some of the backgrounds of the in-house tool development. Additionally, this paper presents the development of the computers and investment of the simulation capacity in order to understand how it has been the enabler of ever more complicated models. It lists the work done during fifty decades. The authors sincerely attempt to make this article as reader-friendly as possible, even though there are over 220 references, which of course demonstrates how dedicated Wärtsilä has been in supporting numerical simulations research in the past fivedecades.
{"title":"History of structural analysis & dynamics of Wärtsilä medium speed engines","authors":"T. Frondelius, Hannu Tienhaara, M. Haataja","doi":"10.23998/RM.69735","DOIUrl":"https://doi.org/10.23998/RM.69735","url":null,"abstract":"This paper opens up the history of structural analysis and dynamics simulations of Wärtsilä engines. It cites already published articles and theses with some backgrounds information. It also discusses some of the backgrounds of the in-house tool development. Additionally, this paper presents the development of the computers and investment of the simulation capacity in order to understand how it has been the enabler of ever more complicated models. It lists the work done during fifty decades. The authors sincerely attempt to make this article as reader-friendly as possible, even though there are over 220 references, which of course demonstrates how dedicated Wärtsilä has been in supporting numerical simulations research in the past fivedecades.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46423555","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}
Terho Tuohineva, I. Väisänen, A. Mäntylä, T. Kuivaniemi, M. Haataja, T. Frondelius
In this paper, two different commercial multibody dynamic (MBD) simulation software cases are studied. Due to the restrictions determined in the conditions of contract, the names of the software are not revealed, instead being called Software S and Software E. The central purpose of this research was to investigate the abilities of Software S in the simulation of a large engine, as a part of the strength analysis process. The abilities were studied by comparing the program with another, here called Software E, which is designed primarily for engine simulations. The capabilities of Software E have been proven after years of usage at Wärtsilä, resulting in its essential role in the strength analysis process today. The aim was to find the shortcomings and restrictions of Software S but also advantages it could bring to the strength analysis process for Wärtsilä. Similar simulation models were also built using both programs during this research. A 16-cylinder V-engine was selected as the subject because of its size in order to obtain further information about the behavior of the program when working with extensive model files. The components of the engine were flexible and were reduced FE models, also called super elements. The forces and contact situations that occur inside the engine were modeled using elements provided by the MBD programs. Different levels of detail of the modeling elements were used to obtain information about the flexibility of the program. The results obtained from time integrations were compared to ensure the similarity of both modeling elements used. Also, this paper reports the calculation times. In addition, a small-scale study was performed for Software S to clarify the effect of the modes used in time integrations towards results accuracy and calculation times. Simulation models were built successfully in both programs, and the results obtained correlated with each other on an adequate level. Significant differences appeared in the features and usability of the programs in general. The GUI of Software S is advanced and user-friendly, whereas Software E is not focused on these features. On the other hand, the modeling element library of Software E covers all of the required features related to large engine simulations, some of which Software S is lacking. This work can be used in assistance when considering buying new software for a company as well as when investigating new development areas that could be improved with new software.
{"title":"Benchmarking of two flexible multibody dynamic simulation software in engine simulations","authors":"Terho Tuohineva, I. Väisänen, A. Mäntylä, T. Kuivaniemi, M. Haataja, T. Frondelius","doi":"10.23998/RM.69961","DOIUrl":"https://doi.org/10.23998/RM.69961","url":null,"abstract":"In this paper, two different commercial multibody dynamic (MBD) simulation software cases are studied. Due to the restrictions determined in the conditions of contract, the names of the software are not revealed, instead being called Software S and Software E. The central purpose of this research was to investigate the abilities of Software S in the simulation of a large engine, as a part of the strength analysis process. The abilities were studied by comparing the program with another, here called Software E, which is designed primarily for engine simulations. The capabilities of Software E have been proven after years of usage at Wärtsilä, resulting in its essential role in the strength analysis process today. The aim was to find the shortcomings and restrictions of Software S but also advantages it could bring to the strength analysis process for Wärtsilä. Similar simulation models were also built using both programs during this research. A 16-cylinder V-engine was selected as the subject because of its size in order to obtain further information about the behavior of the program when working with extensive model files. The components of the engine were flexible and were reduced FE models, also called super elements. The forces and contact situations that occur inside the engine were modeled using elements provided by the MBD programs. Different levels of detail of the modeling elements were used to obtain information about the flexibility of the program. The results obtained from time integrations were compared to ensure the similarity of both modeling elements used. Also, this paper reports the calculation times. In addition, a small-scale study was performed for Software S to clarify the effect of the modes used in time integrations towards results accuracy and calculation times. Simulation models were built successfully in both programs, and the results obtained correlated with each other on an adequate level. Significant differences appeared in the features and usability of the programs in general. The GUI of Software S is advanced and user-friendly, whereas Software E is not focused on these features. On the other hand, the modeling element library of Software E covers all of the required features related to large engine simulations, some of which Software S is lacking. This work can be used in assistance when considering buying new software for a company as well as when investigating new development areas that could be improved with new software.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45040970","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}
In steel frame design, the definition of buckling lengths of members is a basic task. Computers can be used to calculate the eigenmodes and corresponding eigenvalues for the frames and using these the buckling lengths of the members can be defined using Euler's equation. However, it is not always easy to say, which eigenmode should be used for the definition of the buckling length of a specific member. Conservatively, the lowest positive eigenvalue can be used for all members. In this paper, methods to define the buckling length of a specific member is presented. For this assessment, two ideas are considered. The first one uses geometric stiffness matrix locally and the other one uses strain energy measures to identify members taking part in a buckling mode. The behaviour of the methods is shown in several numerical examples. Both methods can be implemented into automated frame design, removing one big gap in the integrated design. This is essential when optimization of frames is considered.
{"title":"Buckling length of a frame member","authors":"Teemu Tiainen, M. Heinisuo","doi":"10.23998/RM.66836","DOIUrl":"https://doi.org/10.23998/RM.66836","url":null,"abstract":"In steel frame design, the definition of buckling lengths of members is a basic task. Computers can be used to calculate the eigenmodes and corresponding eigenvalues for the frames and using these the buckling lengths of the members can be defined using Euler's equation. However, it is not always easy to say, which eigenmode should be used for the definition of the buckling length of a specific member. Conservatively, the lowest positive eigenvalue can be used for all members. In this paper, methods to define the buckling length of a specific member is presented. For this assessment, two ideas are considered. The first one uses geometric stiffness matrix locally and the other one uses strain energy measures to identify members taking part in a buckling mode. The behaviour of the methods is shown in several numerical examples. Both methods can be implemented into automated frame design, removing one big gap in the integrated design. This is essential when optimization of frames is considered.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43489233","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. Belahcen, P. Rasilo, K. Fonteyn, R. Kouhia, Deepak Singh, A. Arkkio
The magnetostriction in electrical steel under rotational magnetization is usually measured with cross-shaped samples. However, the inhomogeneity of the magnetization and stress in the sample might hinder the measured results. In this paper, we investigate this phenomenon by using a magneto-mechanically coupled energy-based model to simulate the sample in a single sheet tester measurement setup, and compare the simulations and measurements. The results show that some anomalies in the measured magnetostriction can be explained by the inhomogeneous magnetization in the sample and the form effect, which result in inhomogeneous stresses and thus affect the observed quantities. The validity of the model as well as the presented statements are ascertained through experiments on the single sheet tester. The backgrounds of the used modelization technique are also detailed.
{"title":"Modeling the stress effect on the measurement of magnetostriction in electrical sheets under rotational magnetization","authors":"A. Belahcen, P. Rasilo, K. Fonteyn, R. Kouhia, Deepak Singh, A. Arkkio","doi":"10.23998/RM.69204","DOIUrl":"https://doi.org/10.23998/RM.69204","url":null,"abstract":"The magnetostriction in electrical steel under rotational magnetization is usually measured with cross-shaped samples. However, the inhomogeneity of the magnetization and stress in the sample might hinder the measured results. In this paper, we investigate this phenomenon by using a magneto-mechanically coupled energy-based model to simulate the sample in a single sheet tester measurement setup, and compare the simulations and measurements. The results show that some anomalies in the measured magnetostriction can be explained by the inhomogeneous magnetization in the sample and the form effect, which result in inhomogeneous stresses and thus affect the observed quantities. The validity of the model as well as the presented statements are ascertained through experiments on the single sheet tester. The backgrounds of the used modelization technique are also detailed.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"51 1","pages":"27-35"},"PeriodicalIF":0.0,"publicationDate":"2018-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41830516","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}
Rakenteiden Mekaniikka -lehti juhli 50-vuotista taivaltaan viime elokuussa Vaasan yliopistossa järjestetyssä juhlaseminaarissa. Seminaarin esitelmien pohjalta kirjoitetuista lyhyistä artikkeleista koottiin lehteemme paksu erikoisnumero (Vol 50, Nro 3), jollaisia on itse asiassa vuosien varrella julkaistu lehdessämme lukuisia. Perinne jatkuu tänäkin vuonna: loppuvuodesta on tarkoitus koota erikoisnumerot sekä Teräsrakentamisen T&K-päivien (15.–16.8. Hämeenlinnassa) että Suomen mekaniikkapäivien (29.–31.8. Helsingissä) esitelmien pohjalta. Lehden uutena päätoimittajana pyrkimykseni on muiltakin osin jatkaa vuosien saatossa hyväksi havaittujen periaatteiden ja linjausten mukaista julkaisutoimintaa. Lehteä on luonnollisesti myös tarkoitus tarpeen mukaan uudistaa. Osa uudistuksista tulee todennäköisesti kytkeytymään lehtemme uuteen verkkojulkaisualustaan, jona on vuoden ajan toiminut Tieteellisten seurain valtuuskunnan ylläpitämä, tiedelehtien toimittamiseen ja julkaisemiseen tarkoitettu Journal.fi-palvelusivusto. Sivustolla on tällä hetkellä noin 60 suomalaista tieteellistä lehteä ja vuosikirjaa ja se käyttää voittoa tavoittelemattoman Public Knowledge Project -yhteenliittymän kehittämää Open Journal Systems -järjestelmää, joka perustuu avoimeen lähdekoodiin ja on tällä hetkellä maailman yleisimmin käytetty julkaisujärjestelmä tieteellisessä julkaisemisessa. Kunhan järjestelmän käyttöönoton alkukankeuksista selvitään, tämän digitaalisen palvelualustan on jatkossa tarkoitus helpottaa lehtemme kirjoittajien, arvioijien ja toimituskunnan työskentelyä, mahdollistaa artikkelien nopeampi julkaiseminen sekä lisätä lehdessä julkaistujen artikkelien näkyvyyttä ja uskottavuutta. Lopuksi haluan vielä lehden puolesta kiittää edeltäjääni, professori Reijo Kouhiaa, joka toimi lehden päätoimittajana viimeiset yksitoista vuotta – toimittaen lehden volyymit 40–50 käsittäen yhteensä 228 vertaisarvioitua artikkelia – ja jatkaa edelleen lehden toimituskunnan jäsenenä. Helsingissä, 1. elokuuta 2018 Jarkko NiiranenRakenteiden Mekaniikka -lehden päätoimittaja, akatemiatutkija, apulaisprofessori
{"title":"Alkusanat","authors":"Jarkko Niiranen","doi":"10.23998/rm.74224","DOIUrl":"https://doi.org/10.23998/rm.74224","url":null,"abstract":"Rakenteiden Mekaniikka -lehti juhli 50-vuotista taivaltaan viime elokuussa Vaasan yliopistossa järjestetyssä juhlaseminaarissa. Seminaarin esitelmien pohjalta kirjoitetuista lyhyistä artikkeleista koottiin lehteemme paksu erikoisnumero (Vol 50, Nro 3), jollaisia on itse asiassa vuosien varrella julkaistu lehdessämme lukuisia. Perinne jatkuu tänäkin vuonna: loppuvuodesta on tarkoitus koota erikoisnumerot sekä Teräsrakentamisen T&K-päivien (15.–16.8. Hämeenlinnassa) että Suomen mekaniikkapäivien (29.–31.8. Helsingissä) esitelmien pohjalta. \u0000Lehden uutena päätoimittajana pyrkimykseni on muiltakin osin jatkaa vuosien saatossa hyväksi havaittujen periaatteiden ja linjausten mukaista julkaisutoimintaa. Lehteä on luonnollisesti myös tarkoitus tarpeen mukaan uudistaa. Osa uudistuksista tulee todennäköisesti kytkeytymään lehtemme uuteen verkkojulkaisualustaan, jona on vuoden ajan toiminut Tieteellisten seurain valtuuskunnan ylläpitämä, tiedelehtien toimittamiseen ja julkaisemiseen tarkoitettu Journal.fi-palvelusivusto. Sivustolla on tällä hetkellä noin 60 suomalaista tieteellistä lehteä ja vuosikirjaa ja se käyttää voittoa tavoittelemattoman Public Knowledge Project -yhteenliittymän kehittämää Open Journal Systems -järjestelmää, joka perustuu avoimeen lähdekoodiin ja on tällä hetkellä maailman yleisimmin käytetty julkaisujärjestelmä tieteellisessä julkaisemisessa. \u0000Kunhan järjestelmän käyttöönoton alkukankeuksista selvitään, tämän digitaalisen palvelualustan on jatkossa tarkoitus helpottaa lehtemme kirjoittajien, arvioijien ja toimituskunnan työskentelyä, mahdollistaa artikkelien nopeampi julkaiseminen sekä lisätä lehdessä julkaistujen artikkelien näkyvyyttä ja uskottavuutta. \u0000Lopuksi haluan vielä lehden puolesta kiittää edeltäjääni, professori Reijo Kouhiaa, joka toimi lehden päätoimittajana viimeiset yksitoista vuotta – toimittaen lehden volyymit 40–50 käsittäen yhteensä 228 vertaisarvioitua artikkelia – ja jatkaa edelleen lehden toimituskunnan jäsenenä. \u0000Helsingissä, 1. elokuuta 2018 \u0000Jarkko NiiranenRakenteiden Mekaniikka -lehden päätoimittaja, akatemiatutkija, apulaisprofessori","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46336877","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 paper presents an experimental procedure to study the effects of pre-existing cracks and damage on the rock behavior under dynamic indentation. To gain better understanding on the mechanism involved in percussive-rotary drilling procedure, a modified Split Hopkinson Pressure Bar device was used to carry out dynamic indentation tests, where rock drill buttons were impacted on rock samples with dimensions of 30 cm × 30 cm × 30 cm. Before the mechanical testing, the samples were thermally shocked using a plasma spray gun for periods of 3, 4, and 6 seconds. The plasma gun produces a powerful heat shocks on the rock sample, and even short exposures can change the surface structure of the samples and provide samples with different crack patterns and surface roughness for experimental testing. The effects of the heat shock damage on the dynamic indentation behavior of the rock were characterized with single- and triple-button indentation tests. The specific destruction work was used to characterize the effects of heat shocks on the material removal during dynamic indentation. The results show that the force-displacement response of the rock does not change much even if the rock surface is severely damaged by the heat shock, however, the destruction work decreases significantly. This means that the same loading removes more volume if the material surface is pre-damaged, and that the efficiency of the indentation process cannot be evaluated from the bit-rock interaction forces alone. The presented experimental framework can be a useful tool for the verification of numerical models where the rock microstructure and especially the microcracks are essential.
{"title":"Experimental study of the dynamic indentation damage in thermally shocked granite","authors":"A. Mardoukhi, M. Hokka, V. Kuokkala","doi":"10.23998/RM.69036","DOIUrl":"https://doi.org/10.23998/RM.69036","url":null,"abstract":"This paper presents an experimental procedure to study the effects of pre-existing cracks and damage on the rock behavior under dynamic indentation. To gain better understanding on the mechanism involved in percussive-rotary drilling procedure, a modified Split Hopkinson Pressure Bar device was used to carry out dynamic indentation tests, where rock drill buttons were impacted on rock samples with dimensions of 30 cm × 30 cm × 30 cm. Before the mechanical testing, the samples were thermally shocked using a plasma spray gun for periods of 3, 4, and 6 seconds. The plasma gun produces a powerful heat shocks on the rock sample, and even short exposures can change the surface structure of the samples and provide samples with different crack patterns and surface roughness for experimental testing. The effects of the heat shock damage on the dynamic indentation behavior of the rock were characterized with single- and triple-button indentation tests. The specific destruction work was used to characterize the effects of heat shocks on the material removal during dynamic indentation. The results show that the force-displacement response of the rock does not change much even if the rock surface is severely damaged by the heat shock, however, the destruction work decreases significantly. This means that the same loading removes more volume if the material surface is pre-damaged, and that the efficiency of the indentation process cannot be evaluated from the bit-rock interaction forces alone. The presented experimental framework can be a useful tool for the verification of numerical models where the rock microstructure and especially the microcracks are essential.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41363069","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. Poutanen, S. Pursiainen, J. Mäkinen, T. Länsivaara
This paper concentrates on the combination of permanent and variable loads in the structural probability theory and its implementation in codes. In the current codes, the permanent and variable loads are sometimes combined independently, and sometimes they are combined dependently. We propose that, for the safest outcome in the standardized load estimation, the actual permanent and variable loads should be combined dependently without any load reduction. The load reduction arising from the independent combination leads to an unsafe design. For example, when the permanent and variable loads are both equal to 1, the combination load is 2 if the dependent combination is applied. However, the value predicted by the model for independent load combination is only ca 1.8. Although the load formation processes are independent, the dependent combination is applied since the load formation and the load combination are different processes. To support our view, we present arguments and examples based on probability theory, physics and statics and relate them with the current codes.
{"title":"Load combination of permanent and variable loads","authors":"T. Poutanen, S. Pursiainen, J. Mäkinen, T. Länsivaara","doi":"10.23998/RM.65175","DOIUrl":"https://doi.org/10.23998/RM.65175","url":null,"abstract":"This paper concentrates on the combination of permanent and variable loads in the structural probability theory and its implementation in codes. In the current codes, the permanent and variable loads are sometimes combined independently, and sometimes they are combined dependently. We propose that, for the safest outcome in the standardized load estimation, the actual permanent and variable loads should be combined dependently without any load reduction. The load reduction arising from the independent combination leads to an unsafe design. For example, when the permanent and variable loads are both equal to 1, the combination load is 2 if the dependent combination is applied. However, the value predicted by the model for independent load combination is only ca 1.8. Although the load formation processes are independent, the dependent combination is applied since the load formation and the load combination are different processes. To support our view, we present arguments and examples based on probability theory, physics and statics and relate them with the current codes.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48437005","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. Saarenheimo, M. Borgerhoff, K. Calonius, Anthony Darraba, A. Hamelin, S. G. Khasraghy, A. Karbassi, C. Schneeberger, Matthias Stadler, M. Tuomala, Pekka Välikangas
Earthquakes and aircraft impacts induce vibrations that propagate throughout the entire building and they need to be considered in designing SSCs (Structures, Systems and Components). Mainly linear calculation methods have been in use in design practice and the codes and standards consider damping ratios only for linear structural analyses. Induced vibrations, especially in damaged concrete structures, have not been studied extensively enough for optimization of structural frameworks and/or qualified systems and components. Experimental data on damping properties of damaged reinforced concrete are needed also for benchmarking analysis programs and methods. Recently, within IMPACT project, a new type of test series considering vibration propagation has been carried out at VTT. The test target is a reinforced concrete structure with two parallel walls connected to a floor slab. The front wall is additionally supported by triangular shaped side walls which are connected to the floor slab too. The test structure is supported on elastomeric bearing pads, with back pipes effective mainly in compression and with bars effective in tension. In order to obtain information on vibration propagation in damaged concrete structure at different levels of damage grades the same structure was tested six times. At each time the mass of the deformable stainless steel missile was 50 kg. The hit point located in the middle of the front wall. The impact velocity was about 110 m/s in the first four tests (V1A-D) and about 60 m/s in the remaining two tests (V1E and F). In this paper, numerical results on tests V1A and V1F are compared with the corresponding experimental ones. The calculated results, such as accelerations, displacements, their response spectra and strains, are compared with experimental measurements. Five finite element (FE) programs are used in computations: Abaqus, Europlexus, LS-DYNA, SOFiSTiK and an in-house code (IHC). Most of the FE-codes in the present study use shell elements. In Abaqus and SOFiSTiK non-linear behaviour of shell section is modelled by dividing the cross section into layers. Reinforcements are also modelled as layers. In Europlexus and IHC, an alternative approach is adopted in which the non-linear behaviour of concrete and reinforcement is homogenized beforehand in the shell thickness direction obtaining relations between stress resultants and generalized strains valid for the shell section. In LS-DYNA, 3D solid elements for modelling concrete and beam elements for modelling reinforcements are used. Equations of motion are integrated with explicit central difference time integration method, except in SOFiSTiK implicit integration method is used. Modelling and computations with the mentioned FE-programs are made independently of each other. Computations with LS-DYNA are carried out as blind exercises. Consideration of the results from benchmarking point of view is still on-going. However it is evident that analysed results fol
{"title":"Numerical studies on vibration propagation and damping test V1","authors":"A. Saarenheimo, M. Borgerhoff, K. Calonius, Anthony Darraba, A. Hamelin, S. G. Khasraghy, A. Karbassi, C. Schneeberger, Matthias Stadler, M. Tuomala, Pekka Välikangas","doi":"10.23998/RM.68954","DOIUrl":"https://doi.org/10.23998/RM.68954","url":null,"abstract":"Earthquakes and aircraft impacts induce vibrations that propagate throughout the entire building and they need to be considered in designing SSCs (Structures, Systems and Components). Mainly linear calculation methods have been in use in design practice and the codes and standards consider damping ratios only for linear structural analyses. Induced vibrations, especially in damaged concrete structures, have not been studied extensively enough for optimization of structural frameworks and/or qualified systems and components. Experimental data on damping properties of damaged reinforced concrete are needed also for benchmarking analysis programs and methods. \u0000Recently, within IMPACT project, a new type of test series considering vibration propagation has been carried out at VTT. The test target is a reinforced concrete structure with two parallel walls connected to a floor slab. The front wall is additionally supported by triangular shaped side walls which are connected to the floor slab too. The test structure is supported on elastomeric bearing pads, with back pipes effective mainly in compression and with bars effective in tension. In order to obtain information on vibration propagation in damaged concrete structure at different levels of damage grades the same structure was tested six times. At each time the mass of the deformable stainless steel missile was 50 kg. The hit point located in the middle of the front wall. The impact velocity was about 110 m/s in the first four tests (V1A-D) and about 60 m/s in the remaining two tests (V1E and F). In this paper, numerical results on tests V1A and V1F are compared with the corresponding experimental ones. \u0000The calculated results, such as accelerations, displacements, their response spectra and strains, are compared with experimental measurements. Five finite element (FE) programs are used in computations: Abaqus, Europlexus, LS-DYNA, SOFiSTiK and an in-house code (IHC). \u0000Most of the FE-codes in the present study use shell elements. In Abaqus and SOFiSTiK non-linear behaviour of shell section is modelled by dividing the cross section into layers. Reinforcements are also modelled as layers. In Europlexus and IHC, an alternative approach is adopted in which the non-linear behaviour of concrete and reinforcement is homogenized beforehand in the shell thickness direction obtaining relations between stress resultants and generalized strains valid for the shell section. In LS-DYNA, 3D solid elements for modelling concrete and beam elements for modelling reinforcements are used. \u0000Equations of motion are integrated with explicit central difference time integration method, except in SOFiSTiK implicit integration method is used. Modelling and computations with the mentioned FE-programs are made independently of each other. Computations with LS-DYNA are carried out as blind exercises. \u0000Consideration of the results from benchmarking point of view is still on-going. However it is evident that analysed results fol","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45619990","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, Jukka Aho, H. Koivurova, T. Frondelius
JuliaFEM is an open source finite element method solver written in the Julia language. This paper presents an implementation of two common model reduction methods: the Guyan reduction and the Craig-Bampton method. The goal was to implement these algorithms to the JuliaFEM platform and demonstrate that the code works correctly. This paper first describes the JuliaFEM concept briefly after which it presents the theory of model reduction, and finally, it demonstrates the implemented functions in an example model. This paper includes instructions for using the implemented algorithms, and reference the code itself in GitHub. The reduced stiness and mass matrices give the same results in both static and dynamic analyses as the original matrices, which proves that the code works correctly. The code runs smoothly on relatively large model of 12.6 million degrees of freedom. In future, damping could be included in the dynamic condensation now that it has been shown to work.
{"title":"Implementing model reduction to the JuliaFEM platform","authors":"Marja Rapo, Jukka Aho, H. Koivurova, T. Frondelius","doi":"10.23998/RM.69026","DOIUrl":"https://doi.org/10.23998/RM.69026","url":null,"abstract":"JuliaFEM is an open source finite element method solver written in the Julia language. This paper presents an implementation of two common model reduction methods: the Guyan reduction and the Craig-Bampton method. The goal was to implement these algorithms to the JuliaFEM platform and demonstrate that the code works correctly. This paper first describes the JuliaFEM concept briefly after which it presents the theory of model reduction, and finally, it demonstrates the implemented functions in an example model. This paper includes instructions for using the implemented algorithms, and reference the code itself in GitHub. The reduced stiness and mass matrices give the same results in both static and dynamic analyses as the original matrices, which proves that the code works correctly. The code runs smoothly on relatively large model of 12.6 million degrees of freedom. In future, damping could be included in the dynamic condensation now that it has been shown to work.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42060564","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}
Petteri Kauppila, Reijo Kouhia, Juha Ojanperä, Timo Saksala, Timo Sorjonen
This article deals with modelling of creep fracture and fatigue of metals. A short description of the physical mechanisms of creep phenomena is given. Developed thermodynamically consistent material model is described in detail. The material parameters are calibrated for the 7CrMoVTiB10-10 steel in the temperature range 500-600 oC. The model is implemented as a user subroutine in the commercial finite element code ANSYS.
{"title":"Metallien virumismurron ja virumisväsymisen mallintaminen","authors":"Petteri Kauppila, Reijo Kouhia, Juha Ojanperä, Timo Saksala, Timo Sorjonen","doi":"10.23998/RM.64657","DOIUrl":"https://doi.org/10.23998/RM.64657","url":null,"abstract":"This article deals with modelling of creep fracture and fatigue of metals. A short description of the physical mechanisms of creep phenomena is given. Developed thermodynamically consistent material model is described in detail. The material parameters are calibrated for the 7CrMoVTiB10-10 steel in the temperature range 500-600 oC. The model is implemented as a user subroutine in the commercial finite element code ANSYS.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"50 1","pages":"420-450"},"PeriodicalIF":0.0,"publicationDate":"2017-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41614478","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：