The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform

Sergio Pellegrino - One of the best experts on this subject based on the ideXlab platform.

  • Closed Cross Section dual matrix composite hinge for deployable structures
    Composite Structures, 2019
    Co-Authors: Maria Sakovsky, Sergio Pellegrino
    Abstract:

    Abstract Dual-matrix composite structures with localized elastomer composite hinges have been proposed to enable packaging with much smaller fold radii than allowed by traditional resin-based fiber reinforced composites. Previous studies have been limited to proof-of-concept of folding capabilities and constitutive modeling of elastomer composites. A novel Closed Cross-Section dual-matrix deployable hinge is studied here to develop the tools for studying the deployment of general dual-matrix structures. A set of tools for the analysis of deployment of this simple structure is developed: an analytic model that minimizes the strain energy in the folded configuration, experimental characterization, and finite element techniques using the LS-Dyna commercial software. The three models are used to predict the packaged shape and deployment moments, and are shown to be in good agreement amongst themselves. The analytic model is used to demonstrate control of the folded shape of the hinge using the stiffness of the elastomer composite. This behavior is verified using finite element models developed in the LS-Dyna commercial code. The simulations are used to predict the localized fold radius of the hinge within 3% and deployment moments within 5% by accounting for the microbuckled stiffness of the elastomer composite.

  • Folding and Deployment of Closed Cross-Section Dual-Matrix Composite Booms
    3rd AIAA Spacecraft Structures Conference, 2016
    Co-Authors: Maria Sakovsky, Sergio Pellegrino, H.m.y.c. Mallikarachchi
    Abstract:

    A dual-matrix composite boom is proposed as a way of realizing a deployable Closed Cross-Section boom that is stiff, lightweight, and can be packaged in small volumes. Little work exists studying the folding and deployment behavior of Closed Cross-Section boom made of composite shells and this paper addresses this by investigating the behavior for two Closed Cross-Section designs. Experimental techniques for measuring the folded shape of curved shells undergoing large deformations is presented. Furthermore, experimental measurements of the moment-rotation response of the two booms are discussed. A study using commercially available finite element software yields simulation techniques for successfully predicting the folded shape of Closed-Cross Section booms. The drawbacks of the software when predicting the moment-rotation response are addressed. The application of these techniques for the chosen designs demonstrate that dual-matrix booms are a promising alternative to existing composite deployable booms.

Maria Sakovsky - One of the best experts on this subject based on the ideXlab platform.

  • Closed Cross Section dual matrix composite hinge for deployable structures
    Composite Structures, 2019
    Co-Authors: Maria Sakovsky, Sergio Pellegrino
    Abstract:

    Abstract Dual-matrix composite structures with localized elastomer composite hinges have been proposed to enable packaging with much smaller fold radii than allowed by traditional resin-based fiber reinforced composites. Previous studies have been limited to proof-of-concept of folding capabilities and constitutive modeling of elastomer composites. A novel Closed Cross-Section dual-matrix deployable hinge is studied here to develop the tools for studying the deployment of general dual-matrix structures. A set of tools for the analysis of deployment of this simple structure is developed: an analytic model that minimizes the strain energy in the folded configuration, experimental characterization, and finite element techniques using the LS-Dyna commercial software. The three models are used to predict the packaged shape and deployment moments, and are shown to be in good agreement amongst themselves. The analytic model is used to demonstrate control of the folded shape of the hinge using the stiffness of the elastomer composite. This behavior is verified using finite element models developed in the LS-Dyna commercial code. The simulations are used to predict the localized fold radius of the hinge within 3% and deployment moments within 5% by accounting for the microbuckled stiffness of the elastomer composite.

  • Folding and Deployment of Closed Cross-Section Dual-Matrix Composite Booms
    3rd AIAA Spacecraft Structures Conference, 2016
    Co-Authors: Maria Sakovsky, Sergio Pellegrino, H.m.y.c. Mallikarachchi
    Abstract:

    A dual-matrix composite boom is proposed as a way of realizing a deployable Closed Cross-Section boom that is stiff, lightweight, and can be packaged in small volumes. Little work exists studying the folding and deployment behavior of Closed Cross-Section boom made of composite shells and this paper addresses this by investigating the behavior for two Closed Cross-Section designs. Experimental techniques for measuring the folded shape of curved shells undergoing large deformations is presented. Furthermore, experimental measurements of the moment-rotation response of the two booms are discussed. A study using commercially available finite element software yields simulation techniques for successfully predicting the folded shape of Closed-Cross Section booms. The drawbacks of the software when predicting the moment-rotation response are addressed. The application of these techniques for the chosen designs demonstrate that dual-matrix booms are a promising alternative to existing composite deployable booms.

Tomasz Kubiak - One of the best experts on this subject based on the ideXlab platform.

  • influence of residual stresses on the buckling behaviour of thin walled composite tubes with Closed Cross Section numerical and experimental investigations
    Composite Structures, 2019
    Co-Authors: Pawel Czapski, Tomasz Kubiak
    Abstract:

    Abstract The aim of this research is to investigate the influence of residual stresses on the behaviour of thin-walled laminates during compression until failure. We investigate the compression of a squared Cross-Section, GFRP columns with dimensions: (width × height × thickness): 80 × 80 × 2 mm. The length of the tubes is equal to 250 mm. The material used to manufacture the specimens was eight-layered pre-preg and we analysed six combinations of angular arrangements. The autoclaving technique was employed to produce the samples. In this paper, a new FE model of tubes’ compression including residual stresses from the manufacturing process is presented. The FE model where residual stresses are not taken into account has been underestimated by the real structures’ behaviour. Therefore, the first part of the study is devoted to preparing a simplified model of the curing process, while in the second the manufacturing and curing stresses are transferred to the model of compression. Backed by experimental data, the study shows that residual stresses have a significant influence on buckling performance, which finds confirmation in the experiments.

  • load carrying capacity of thin walled composite structures
    Composite Structures, 2005
    Co-Authors: Zbigniew Kolakowski, Tomasz Kubiak
    Abstract:

    Abstract In the paper some basic ideas in approach to stability, post buckling behaviour and load carrying capacity of thin-walled composite structures are presented. Authors do not present equations that could only make the understanding of this issue “harder”. Thin walled composite beam-coloumns with open and Closed Cross-Section (channel and square Cross-Section) are calculated as an example. In order to analyse the stability and the structure performance after its loss, the ANSYS 5.7 package and authors' software has been used. Results obtained from both applied methods are compared. Presented examples show that the sole application of the FEM does not guarantee to obtain correct results of load carrying capacity and postbuckling path.

Zbigniew Kolakowski - One of the best experts on this subject based on the ideXlab platform.

  • non linear multi mode buckling of non symmetric fml fgm thin walled columns with open Cross Sections under compression
    Composite Structures, 2017
    Co-Authors: Andrzej Teter, Radoslaw J Mania, Zbigniew Kolakowski
    Abstract:

    Abstract Current paper is the second part of Kolakowski Z, Mania RJ paper entitled: “ Influence of the coupling matrix B on the interactive buckling of FML-FGM columns with Closed Cross-Section under axial compression ”, Composite Structures, in press. The problem of non-linear multi-mode buckling of thin-walled columns with open Cross-Sections made of Functionally Graded Materials ( FGMs ) and Fibre Metal Laminate ( FML ) was discussed. FGM layers are a thermal barrier, whereas the FML composite provides rigidity and strength. This new hybrid thin-walled structure is very interesting but there are no interactive buckling solutions. The non-linear problem of buckling was solved with the analytical-numerical method ( ANM ) based on Koiter’s theory. An interaction of global buckling mode with many different local buckling modes was discussed. A plate model and the classical laminate theory are used to define government relations. The differential equilibrium equations were obtained with a variational method. Each column was made of an FML sublayer, a single AL-TiC-type FGM layer and/or a TiC ceramic layer. The FML sublayer consisted of two outer aluminium layers and even carbon-epoxy prepreg interlayers. The layup configuration of the FML/FGM composite is non-symmetric, so the coupling matrix B is non-trivial. Simply supported columns are under mechanical compression only.

  • load carrying capacity of thin walled composite structures
    Composite Structures, 2005
    Co-Authors: Zbigniew Kolakowski, Tomasz Kubiak
    Abstract:

    Abstract In the paper some basic ideas in approach to stability, post buckling behaviour and load carrying capacity of thin-walled composite structures are presented. Authors do not present equations that could only make the understanding of this issue “harder”. Thin walled composite beam-coloumns with open and Closed Cross-Section (channel and square Cross-Section) are calculated as an example. In order to analyse the stability and the structure performance after its loss, the ANSYS 5.7 package and authors' software has been used. Results obtained from both applied methods are compared. Presented examples show that the sole application of the FEM does not guarantee to obtain correct results of load carrying capacity and postbuckling path.

Ryan Bona - One of the best experts on this subject based on the ideXlab platform.

  • Finite element modelling and parametric studies of semi-Closed thin-walled steel polygonal columns
    Czech Technical University in Prague. Computing and Information Centre., 2017
    Co-Authors: Ryan Bona
    Abstract:

    Objective of this work is to study the proposed structural Sections in design situation and to investigate possible design models. The expected structural behavior of the column is a mixture between the open and Closed Cross-Section. These cases will be investigated through numerical study. In this thesis presented a comprehensive parametric study on the ultimate strength of proposed coldformed steel columns using the Finite Element package ABAQUS. FE models were first developer for columns by using automation that was made through MATLAB and Python script. The buckling and non-linear FE study was done for the investigation of local (L), distortional (D) and global (G) possible buckling failures and ultimate resistance, respectively. Modelling issues such as boundary conditions, meshing, initial imperfections, material models, and non-linear solution controls in FEA were also addressed.Objective of this work is to study the proposed structural Sections in design situation and to investigate possible design models. The expected structural behavior of the column is a mixture between the open and Closed Cross-Section. These cases will be investigated through numerical study. In this thesis presented a comprehensive parametric study on the ultimate strength of proposed coldformed steel columns using the Finite Element package ABAQUS. FE models were first developer for columns by using automation that was made through MATLAB and Python script. The buckling and non-linear FE study was done for the investigation of local (L), distortional (D) and global (G) possible buckling failures and ultimate resistance, respectively. Modelling issues such as boundary conditions, meshing, initial imperfections, material models, and non-linear solution controls in FEA were also addressed

  • Finite Element Modelling and Parametric Studies of Semi-Closed Thin-Walled Steel Polygonal Columns - Application on Steel Lattice Towers for Wind Turbines
    Luleå tekniska universitet Institutionen för samhällsbyggnad och naturresurser, 2017
    Co-Authors: Ryan Bona
    Abstract:

    The trend of structural engineering in the recent years is toward the use of lighter and moreeconomical structural elements. In steel construction, peculiarly, thin-walled structural elements arebecoming more popular and have a growing importance. Improved techniques in a manufacturing ofthin-walled elements have led to increased competitiveness of such products in the buildingapplications. Some examples of such structural element can be found in everyday life in form ofcolumns, studs, roofing trusses, and light-weight frames. However, the use of slender profiles and acomplex Cross Sections shape lead to requirements to study instability phenomenon in a form of local,distortional, flexural, torsional and coupled instability. Such complex structural behavior is inevitablyaccompanied by demand to improve calculation methods and design provisions. In this thesis, aninnovative solution of structural element composed of thin-walled plates is proposed for theapplication on lattice support structure of wind turbine.Thin-walled cold-formed profiles are steel products usually made from cold rolled coils and folded inthe second step. In this way, only open profiles can be produced. The predominant problem of theopen Cross-Section is the excessive torsional effect caused by the non-coincidence between the shearcenter and mass center, and a poor torsional resistance. A better response is possible with Closed CrossSections, but such profiles could not be produced by the folding. The solution is to make semi-ClosedSection by assembling them into polygonal profiles with mechanical fasteners, as presented in thisthesis.Objective of this work is to study the proposed structural Sections in design situation and toinvestigate possible design models. The expected structural behavior of the column is a mixturebetween the open and Closed Cross-Section. These cases will be investigated through numerical study.In this thesis presented a comprehensive parametric study on the ultimate strength of proposed coldformedsteel columns using the Finite Element package ABAQUS. FE models were first developedfor columns by using automation that was made through MATLAB and Python script. The bucklingand non-linear FE study was done for the investigation of local (L), distortional (D) and global (G)possible buckling failures and ultimate resistance, respectively. Modelling issues such as boundaryconditions, meshing, initial imperfections, material models, and non-linear solution controls in FEAwere also addressed.The parametric study involved series of profiles of built-up polygonal Cross-Section types with variedthickness (t), number of corners (n), diameter (d), slenderness (slend), yield strength (fy), number ofpoints along corner radii (np), extension lip length (lext), gusset plate thickness (tg), member length (l),and density of fasteners (s/d ratio), loaded in compression and bending moment. The bending momentoccurs as the effect of forces acting on the connection. The purpose of this analysis is to study thecritical load, Cross-Sectional behavior, influence of the amplitude of initial imperfections on theultimate load, and influence of each parameter used in the analysis through Full Factorial Design