The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Sean B. Leen - One of the best experts on this subject based on the ideXlab platform.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks
    Composites Part A: Applied Science and Manufacturing, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)-cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks Part A Applied science and manufacturing
    Composites, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)–cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

D. M. Grogan - One of the best experts on this subject based on the ideXlab platform.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks
    Composites Part A: Applied Science and Manufacturing, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)-cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks Part A Applied science and manufacturing
    Composites, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)–cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

Alastair Johnson - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of impact and Damage tolerance in aerospace composite structures
    Numerical Modelling of Failure in Advanced Composite Materials, 2015
    Co-Authors: Alastair Johnson, Nathalie Toso-pentecote, Dominik Schueler
    Abstract:

    This chapter discusses numerical methods that are used for predicting impact Damage in advanced composite structures. To support the acceptance by industry for design and certification of composite aircraft structures, composites Damage models are required for implementation in commercial finite element (FE) codes and validation at specimen and substructure level. DLR experience on modelling Damage progression and failure in composite structures under impact is reviewed based on meso-scale composites Ply Damage models and an energy-based delamination failure criteria in explicit FE codes. The numerical methods are applied to predict impact Damage and Damage tolerance in stiffened and unstiffened aircraft panels from hard and soft body impacts, including pre-stressed panels subjected to impact loads. Issues concerned with validation of computational methods for certification by analysis are discussed.

  • Failure mechanisms and energy absorption in composite elements under axial crush
    Key Engineering Materials, 2011
    Co-Authors: Alastair Johnson, Matthew David
    Abstract:

    Test methods are presented to determine failure modes and energy absorption properties of composite crash structural elements from quasi-static tests on chamfered carbon fabric/epoxy tube segment specimens under axial compression loads. High speed film and CT scans of failed specimens are used to identify trigger mechanisms, failure mode evolution at the crush front and failure processes during steady crushing. FE models of failure were developed which could be the basis for materials selection and design procedures for crashworthy composite structures. These are based on meso-scale composites Ply Damage models combined with cohesive interfaces to represent delamination failures, which Damage and fail when the interface fracture energy is reached. The models are implemented in an explicit FE code and parameters for the Ply Damage and delamination models were obtained from related materials test programmes. The FE models were applied to simulate axial crushing in tube segments and C-channels, showing good predictions of measured peak forces at failure initiation, steady crush forces and total energy absorption.

  • Status of FE simulation methods for certification of composite structures under high velocity impact
    2009
    Co-Authors: Alastair Johnson, Nathalie Toso-pentecote
    Abstract:

    The paper discusses FE simulation methods in use for predicting impact Damage in advanced composite structures. Before these simulation tools are accepted by the industry for design and certification of composite aircraft structures, composites Damage models have to be developed, implemented in commercial FE codes and validation studies at specimen and substructure level have to be performed. For vulnerability analysis the DLR uses meso-scale composites Ply Damage models with an energy based delamination failure criteria in explicit FE codes to study Damage progression in composite structures under impact. The methods developed are summarised in the paper and applied to predict impact Damage in stiffened aircraft panels from hard debris impact and tyre rubber fragments. Issues concerned with use of such computational methods for certification by analysis are discussed.

  • Determination of delamination Damage in composites under impact loads
    Delamination Behaviour of Composites, 2008
    Co-Authors: Alastair Johnson, Nathalie Toso-pentecote
    Abstract:

    This contribution describes recent progress on materials modelling and numerical simulation of fibre reinforced composite shell structures subjected to high velocity impact loads. A Continuum Damage Mechanics (CDM) model for fibre reinforced composites is applied to model both in-Ply Damage and delamination failure during impact loading. The CDM model has been implemented in a commercial explicit finite element (FE) code in which a laminate is modelled by stacked shell elements with cohesive interfaces which fracture when a delamination failure energy criterion is reached. A comparison of structural response and failure modes from numerical simulations is then conducted. In particular, emphasis is put on the influence of delamination Damage on the impact behaviour of composite plates and stiffened panels. Delamination Damage is measured in low velocity drop tower impact tests and also in high velocity gas gun tests on composite plates with steel projectiles carried out at the DLR. In both types of test it is seen that at lower impact energies delamination Damage was often the main Damage mechanism, whereas at higher impact energies there was fibre fracture and plate penetration by the hard projectiles. In this case, the presence of some delamination provides an additional energy absorption mechanism in the composite plate, which can reduce complete penetration. It follows that modelling and analysis of impact Damage require composites failure models which include both in-plane Ply Damage and delamination Damage.

  • Modelling Impact Damage in Stiffened Composite Panels
    2007
    Co-Authors: Nathalie Toso-pentecote, Alastair Johnson, Zohreh Ebrahimi
    Abstract:

    This paper describes recent progress on materials modelling and numerical simulation of fibre reinforced composite shell structures subjected to high velocity impact loads. A Continuum Damage Mechanics (CDM) model for fibre reinforced composites is applied to model both in-Ply Damage and delamination failure during impact loading. The CDM model has been implemented in a commercial explicit finite element (FE) code in which a laminate is modelled by stacked shell elements with cohesive interfaces which fracture when a delamination failure energy criterion is reached. The code is applied to predict the response of stringer stiffened composite panels subjected to gas gun impact tests by steel impactors under a range of test conditions. A comparison of structural response and failure modes from numerical simulations and impact tests shows good agreement for the prediction of delamination Damage and shell penetration at higher impact energies.

Conchúr M. Ó Brádaigh - One of the best experts on this subject based on the ideXlab platform.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks
    Composites Part A: Applied Science and Manufacturing, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)-cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks Part A Applied science and manufacturing
    Composites, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)–cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

J. Patrick Mcgarry - One of the best experts on this subject based on the ideXlab platform.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks
    Composites Part A: Applied Science and Manufacturing, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)-cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.

  • Damage and permeability in tape-laid thermoplastic composite cryogenic tanks Part A Applied science and manufacturing
    Composites, 2015
    Co-Authors: D. M. Grogan, Conchúr M. Ó Brádaigh, J. Patrick Mcgarry, Sean B. Leen
    Abstract:

    This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate Damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)–cohesive zone methodology which is used to predict intra- and inter-Ply Damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads.