Delamination is one of the major failure mechanisms for composites and traditionally the simulation requires high expertise in fracture mechanics and dedicated knowledge of the Finite Element Analysis (FEA) tool. Yet, the simulation cycle times are high. Geometrically nonlinear analysis approach, which is based on the Reissner-Mindlin-Von K´arm´an type shell facet model, has been implemented into the Elmer FE solver. Altair ESAComp software runs the Elmer Solver in the background. A post-processing capability, which enables the prediction of the delamination onset from the FEA output, has been implemented into the AltairESAComp software. A Virtual Crack Closure Technique (VCCT) specifically developed for shell elements defining the Strain Energy Release Rate (SERR) related to the different delamination modes at the crack front is used. The onset of delamination is predicted using the relevant delamination criteria that utilize the SERR data and material allowables in the form of fracture toughness. The modeling methodology is presented for laminates including initial through-the-width delamination. Examples include delamination in the solid laminate and debonding of the skin laminate in the sandwich structure. Rather coarse FE mesh has proved to yield good results when compared to typical approaches that utilize the standard VCCT or Cohesive Zone Elements.
分层是复合材料的主要失效机制之一，传统上模拟需要在断裂力学方面的高度专业知识和有限元分析（FEA）工具的专门知识。然而，模拟周期时间很长。几何非线性分析方法基于Reissner Mindlin Von K´arm´an型壳面模型，已在Elmer有限元求解器中实现。Altair ESAComp软件在后台运行Elmer解算器。AltairESAComp软件中已经实现了后处理功能，该功能能够从有限元分析输出中预测分层开始。使用了一种专门为壳体元件开发的虚拟裂纹闭合技术（VCCT），该技术定义了与裂纹前沿不同分层模式相关的应变能释放率（SERR）。使用相关分层标准预测分层的开始，该标准利用SERR数据和断裂韧性形式的材料容许值。提出了包括初始贯穿宽度分层在内的层压板的建模方法。实例包括固体层压板中的分层和夹层结构中的表皮层压板的脱粘。与使用标准VCCT或内聚区单元的典型方法相比，相当粗糙的有限元网格已被证明能产生良好的结果。
{"title":"A model for fast delamination analysis of laminated composite structures","authors":"H. Katajisto, P. Kere, M. Lyly","doi":"10.23998/rm.82730","DOIUrl":"https://doi.org/10.23998/rm.82730","url":null,"abstract":"Delamination is one of the major failure mechanisms for composites and traditionally the simulation requires high expertise in fracture mechanics and dedicated knowledge of the Finite Element Analysis (FEA) tool. Yet, the simulation cycle times are high. Geometrically nonlinear analysis approach, which is based on the Reissner-Mindlin-Von K´arm´an type shell facet model, has been implemented into the Elmer FE solver. Altair ESAComp software runs the Elmer Solver in the background. A post-processing capability, which enables the prediction of the delamination onset from the FEA output, has been implemented into the AltairESAComp software. A Virtual Crack Closure Technique (VCCT) specifically developed for shell elements defining the Strain Energy Release Rate (SERR) related to the different delamination modes at the crack front is used. The onset of delamination is predicted using the relevant delamination criteria that utilize the SERR data and material allowables in the form of fracture toughness. The modeling methodology is presented for laminates including initial through-the-width delamination. Examples include delamination in the solid laminate and debonding of the skin laminate in the sandwich structure. Rather coarse FE mesh has proved to yield good results when compared to typical approaches that utilize the standard VCCT or Cohesive Zone Elements.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"67-84"},"PeriodicalIF":0.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46394758","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 article deals with determining sound transmission losses in plane structures. The subject is considered from the perspective of a civil engineer. Especially plates and structures composed of plates are dealt with. Equations and analytical solutions of sound transmission are derived carefully. The computational process of determining the parameters describing the sound transmission properties of structures is demonstrated by numerical examples.
{"title":"Tasorakenteiden ilmaääneneristävyyden arvioinnista","authors":"Jukka Aalto","doi":"10.23998/rm.85743","DOIUrl":"https://doi.org/10.23998/rm.85743","url":null,"abstract":"The article deals with determining sound transmission losses in plane structures. The subject is considered from the perspective of a civil engineer. Especially plates and structures composed of plates are dealt with. Equations and analytical solutions of sound transmission are derived carefully. The computational process of determining the parameters describing the sound transmission properties of structures is demonstrated by numerical examples.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"145-179"},"PeriodicalIF":0.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42491794","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}
Kirkkovenesoudulle saadaan yksinkertaistettu malli yhdistämällä veneen liikeyhtälö ja airojen rotaatioyhtälö. Voima vedossa asetetaan yhtäsuureksi kuin vastus koko syklin eli vedon ja airon palautuksen aikana. Veneen matkavauhdin määrittävät veneen liikevastus ja vetojen lukumäärä minuutissa, vedon pituus sekä syklin rytmi. Soutajan kestävyys arvioidaan soutajan hapenottokyvystä.
{"title":"Kirkkoveneen soutamisen malli","authors":"Matti A. Ranta, Laila Hosia","doi":"10.23998/rm.82948","DOIUrl":"https://doi.org/10.23998/rm.82948","url":null,"abstract":"Kirkkovenesoudulle saadaan yksinkertaistettu malli yhdistämällä veneen liikeyhtälö ja airojen rotaatioyhtälö. Voima vedossa asetetaan yhtäsuureksi kuin vastus koko syklin eli vedon ja airon palautuksen aikana. Veneen matkavauhdin määrittävät veneen liikevastus ja vetojen lukumäärä minuutissa, vedon pituus sekä syklin rytmi. Soutajan kestävyys arvioidaan soutajan hapenottokyvystä.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"28-34"},"PeriodicalIF":0.0,"publicationDate":"2020-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43208237","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}
J. Juoksukangas, J. Hintikka, A. Lehtovaara, A. Mäntylä, J. Vaara, T. Frondelius
Fretting fatigue and wear may exist if two parts have small amplitude relative rubbing between the contacting surfaces. A peak in the coefficient of friction typically occurs during the first thousands of loading cycles in dry fretting contact with quenched and tempered steel. This peak is related to adhesive friction and wear causing non-Coulomb friction and high local contact stresses possibly leading to cracking. The focus of the study is the effect of different experimental methods on the frictional behavior of the fretting contact between the steel surfaces. The use of pre-corroded specimens and contact lubrication delayed and reduced the initial peak. However, a pre-added third body layer removed the peak completely.
{"title":"Avoiding the high friction peak in fretting contact","authors":"J. Juoksukangas, J. Hintikka, A. Lehtovaara, A. Mäntylä, J. Vaara, T. Frondelius","doi":"10.23998/rm.76266","DOIUrl":"https://doi.org/10.23998/rm.76266","url":null,"abstract":"Fretting fatigue and wear may exist if two parts have small amplitude relative rubbing between the contacting surfaces. A peak in the coefficient of friction typically occurs during the first thousands of loading cycles in dry fretting contact with quenched and tempered steel. This peak is related to adhesive friction and wear causing non-Coulomb friction and high local contact stresses possibly leading to cracking. The focus of the study is the effect of different experimental methods on the frictional behavior of the fretting contact between the steel surfaces. The use of pre-corroded specimens and contact lubrication delayed and reduced the initial peak. However, a pre-added third body layer removed the peak completely.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"12-19"},"PeriodicalIF":0.0,"publicationDate":"2020-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43835151","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 johdettavan tuulimyllyn yksinkertaisen aerodynaamisen mallin mukaan kolmilapaisen tuulimyllyn tehoa määritettäessä tulee ottaa huomioon seuraavat tekijät: tuulen nopeus, lavan profiilin aerodynaamiset ominaisuudet, sakkaus ja kierrosnopeus, säädöt ja hyötysuhde.
{"title":"Tuulimyllyn yksinkertainen aerodynaaminen malli","authors":"Matti A. Ranta","doi":"10.23998/rm.82949","DOIUrl":"https://doi.org/10.23998/rm.82949","url":null,"abstract":"Artikkelissa johdettavan tuulimyllyn yksinkertaisen aerodynaamisen mallin mukaan kolmilapaisen tuulimyllyn tehoa määritettäessä tulee ottaa huomioon seuraavat tekijät: tuulen nopeus, lavan profiilin aerodynaamiset ominaisuudet, sakkaus ja kierrosnopeus, säädöt ja hyötysuhde.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43111072","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}
Thermal distribution and fluctuation in any piping component due to turbulent mixing of flows with different temperatures vary greatly. Usually, computational fluid dynamics (CFD) tools are used for estimation of flows in piping components. Fatigue that results from fluctuating thermal mass flow across the components can be computed by coupling the CFD results with structural mechanics based finite element (FE) results. However, this procedure is laborious and computationally very expensive. A fluid temperature function has been developed in this paper as a function of internal wall coordinates and time by interpolating experimental or CFD results. Bicubic interpolation function has been used for accurate interpolation. Finally, a thermal transient FE analysis for an actual Tee from a nuclear power plant (NPP) was performed by using the developed fluid temperature function and interpolated CFD results.
{"title":"Thermal transient finite element computation of a mixing Tee by utilizing CFD results","authors":"Q. Saifi, O. Cronvall","doi":"10.23998/rm.76158","DOIUrl":"https://doi.org/10.23998/rm.76158","url":null,"abstract":"Thermal distribution and fluctuation in any piping component due to turbulent mixing of flows with different temperatures vary greatly. Usually, computational fluid dynamics (CFD) tools are used for estimation of flows in piping components. Fatigue that results from fluctuating thermal mass flow across the components can be computed by coupling the CFD results with structural mechanics based finite element (FE) results. However, this procedure is laborious and computationally very expensive. A fluid temperature function has been developed in this paper as a function of internal wall coordinates and time by interpolating experimental or CFD results. Bicubic interpolation function has been used for accurate interpolation. Finally, a thermal transient FE analysis for an actual Tee from a nuclear power plant (NPP) was performed by using the developed fluid temperature function and interpolated CFD results.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"53 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2020-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44116581","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. Mäntylä, J. Juoksukangas, J. Hintikka, T. Frondelius, A. Lehtovaara
This article presents a robust Finite-Element-Method-based wear simulation method, particularly suitable for fretting contacts. This method utilizes the contact subroutine in a commercial finite element solver Abaqus. It is based on a user-defined contact formulation for both normal and tangential directions. For the normal contact direction, a nodal gap field is calculated by using a simple Archard's wear equation to describe the depth of material removal due to wear. The wear field is included in the contact pressure calculation to allow simulation of wear and contact stress evolution during the loading cycles. The main advantage of this approach is that all contact variables are accessible inside the routine, which allows full coupling between normal and tangential contact variables. Also, there is no need for mesh modifications during the solution. This makes the implementation flexible, robust and particularly suitable for fretting cases where friction and tangential contact stiffness play an essential role. The method is applied to the bolted joint type fretting test case. The methodology is also fully applicable to complex real component simulations.
{"title":"FEM-based wear simulation for fretting contacts","authors":"A. Mäntylä, J. Juoksukangas, J. Hintikka, T. Frondelius, A. Lehtovaara","doi":"10.23998/rm.76261","DOIUrl":"https://doi.org/10.23998/rm.76261","url":null,"abstract":"This article presents a robust Finite-Element-Method-based wear simulation method, particularly suitable for fretting contacts. This method utilizes the contact subroutine in a commercial finite element solver Abaqus. It is based on a user-defined contact formulation for both normal and tangential directions. For the normal contact direction, a nodal gap field is calculated by using a simple Archard's wear equation to describe the depth of material removal due to wear. The wear field is included in the contact pressure calculation to allow simulation of wear and contact stress evolution during the loading cycles. The main advantage of this approach is that all contact variables are accessible inside the routine, which allows full coupling between normal and tangential contact variables. Also, there is no need for mesh modifications during the solution. This makes the implementation flexible, robust and particularly suitable for fretting cases where friction and tangential contact stiffness play an essential role. The method is applied to the bolted joint type fretting test case. The methodology is also fully applicable to complex real component simulations.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41962869","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. Kaarakka, Tero Frondelius, Osmo Kaleva, Reijo Kouhia, Heikki Orelma, Joona Vaara
Artikkelissa tarkastellaan evoluutioyhtälöpohjaisen jännitysväsymismallin stokastista laajennusta. Esitetty malli on muodostettu yleisten kontinuumimekaniikan periaatteiden mukaisesti ja on siten luonnostaan moniakselinen ja käsittelee kaikki jännityskomponentit ekvivalentilla tavalla. Malli soveltuu myos mielivaltaiselle kuormitushistorialle. Esimerkkinä tarkastellaan yksinkertaista valkoisella kohinalla häirityn säännollisen kuormituksen aiheuttaman elinikäaennusteen jakaumaa.
{"title":"Jännitysväsymisen kontinuumimalli","authors":"T. Kaarakka, Tero Frondelius, Osmo Kaleva, Reijo Kouhia, Heikki Orelma, Joona Vaara","doi":"10.23998/rm.76262","DOIUrl":"https://doi.org/10.23998/rm.76262","url":null,"abstract":"Artikkelissa tarkastellaan evoluutioyhtälöpohjaisen jännitysväsymismallin stokastista laajennusta. Esitetty malli on muodostettu yleisten kontinuumimekaniikan periaatteiden mukaisesti ja on siten luonnostaan moniakselinen ja käsittelee kaikki jännityskomponentit ekvivalentilla tavalla. Malli soveltuu myos mielivaltaiselle kuormitushistorialle. Esimerkkinä tarkastellaan yksinkertaista valkoisella kohinalla häirityn säännollisen kuormituksen aiheuttaman elinikäaennusteen jakaumaa. \u0000 ","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":"46096534","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 study concerns the long-term operation (LTO) of a boiling water reactor (BWR) reactor pressure vessel (RPV) and its internals. The main parts of this study are: survey on the susceptibility to degradation mechanisms, and computational time limited ageing analyses (TLAAs). The ageing of nuclear power plants (NPPs) emphasizes the need to anticipate the possible degradation mechanisms. The BWR survey on the susceptibility to these mechanisms uses the RPVs and significant internals of the Olkiluoto power plant units OL1 and OL2 as a pilot project. For the components that screened in, the potential to brittle, ductile or other degradation is determined. This was carried out by applying structural mechanics and fracture mechanics procedures. Only some most significant cases and results are presented here.
{"title":"Long-term operation of a boiling pressure vessel and its internals","authors":"O. Cronvall","doi":"10.23998/rm.76141","DOIUrl":"https://doi.org/10.23998/rm.76141","url":null,"abstract":"This study concerns the long-term operation (LTO) of a boiling water reactor (BWR) reactor pressure vessel (RPV) and its internals. The main parts of this study are: survey on the susceptibility to degradation mechanisms, and computational time limited ageing analyses (TLAAs). The ageing of nuclear power plants (NPPs) emphasizes the need to anticipate the possible degradation mechanisms. The BWR survey on the susceptibility to these mechanisms uses the RPVs and significant internals of the Olkiluoto power plant units OL1 and OL2 as a pilot project. For the components that screened in, the potential to brittle, ductile or other degradation is determined. This was carried out by applying structural mechanics and fracture mechanics procedures. Only some most significant cases and results are presented here.","PeriodicalId":52331,"journal":{"name":"Rakenteiden Mekaniikka","volume":"52 1","pages":"200-221"},"PeriodicalIF":0.0,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48007481","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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