The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Gabriel Laplante - One of the best experts on this subject based on the ideXlab platform.

  • Acoustic Emission Monitoring of Interlaminar Delamination Onset in Carbon Fibre Composites
    Structural Health Monitoring: An International Journal, 2013
    Co-Authors: Ian Silversides, A. Maslouhi, Gabriel Laplante
    Abstract:

    This article presents the development of an experimental methodology based on acoustic emission wave detection for determining Delamination Onset and propagation in carbon fibre composite materials under quasi-static and fatigue loading. Delamination was investigated in quasi-static interlaminar fracture testing over a wide range of mixed-mode ratios (GII/GT = 0, 0.3, 0.5 and 1) for unidirectional and woven samples. An acoustic emission wave detection method was developed to detect Delamination Onset, and the corresponding fracture toughness was computed. Interlaminar fracture toughness was also calculated by beam theory and from finite element analysis with the virtual crack closure technique. The mechanical testing results, acoustic emission monitoring and numerical model’s interlaminar fracture toughness were used to define Delamination initiation criteria by drawing two-dimensional envelopes corresponding to GC = f(GII/GT). The acoustic emission wave detection method showed damage accumulation before ...

  • environmental effects on mode ii fatigue Delamination growth in an aerospace grade carbon epoxy composite
    Composites Part A-applied Science and Manufacturing, 2012
    Co-Authors: Benoit Landry, Gabriel Laplante, Luc R Leblanc
    Abstract:

    Abstract An investigation of the effects of water, hydraulic fluid and deicing fluid exposure on mode II Delamination propagation in an aerospace grade composite is presented. All exposed specimens suffered a loss in Delamination toughness and an increase in fatigue Delamination growth rate , which was particularly significant for deicing fluid exposure. The number of cycles for Delamination Onset was also reduced by these exposures, although scanning electron micrographs showed no significant differences between the fracture pattern of dry and exposed specimens. It was also shown that environmental effects can be simply accounted for in a cohesive zone based finite element model.

G Allegri - One of the best experts on this subject based on the ideXlab platform.

  • simulation of progressive failure in laminated composites under variable environmental conditions
    Materials & Design, 2020
    Co-Authors: Ganapathi Ammasai Sengodan, G Allegri, Stephen R Hallett
    Abstract:

    Abstract This paper presents the development, calibration and finite element implementation of a novel set of phenomenological equations describing the effect of temperature and moisture on the stiffness, strength and toughness properties of fibre-reinforced plastics. An extension of the classical Zhurkov's kinetic approach is proposed to describe the effect of temperature and moisture on the ply-level matrix-dominated strength properties. The phenomenological equations are implemented into a finite-element simulation framework, consisting of a smeared crack approach for modelling intralaminar and translaminar failure, coupled with a bi-linear cohesive zone approach to describe Delamination Onset and progressive growth. The modelling approach is calibrated by means of experimental data in the open literature for the carbon-epoxy material IM7/8552. Validation case studies for the simulation strategy include quasi-isotropic short beam shear coupons and open-hole specimens subject to tension. It is demonstrated that the proposed simulation framework provides a comprehensive quantitative description of the role played by environmental effects in terms of development and interaction of intralaminar, interlaminar and translaminar damage processes.

  • a simplified layered beam approach for predicting ply drop Delamination in thick composite laminates
    Materials & Design, 2016
    Co-Authors: Khong Wui Gan, G Allegri, Stephen R Hallett
    Abstract:

    Abstract The prediction of Delamination Onset is a challenging task in the design of thick tapered composite laminates, where multiple ply terminations (“drop-offs”) are present. This paper addresses the development of a global-local finite element-based design approach for tapered laminates, whereby layered Timoshenko beam models are employed to predict Delamination initiation from individual drop-offs. This modelling strategy provides a fast and conservative method for evaluating the strength of tapered composite laminates. Parametric test cases are presented in order to validate the methodology and understand its limitations. Finally, the application of the tool to a relatively thick tapered composite test specimen comprising multiple ply-drops is demonstrated.

  • a non linear damage evolution model for mode ii fatigue Delamination Onset and growth
    International Journal of Fatigue, 2012
    Co-Authors: G Allegri, Michael R Wisnom
    Abstract:

    Abstract A novel approach is proposed describing both the Onset and growth of Delaminations in fibre-reinforced laminates under pure mode II constant amplitude loading with the same damage evolution rule, unifying these two aspects of the material behaviour that are normally treated separately. A scalar damage variable is introduced to represent the fraction of overall fatigue endurance used up at ply interfaces as a function of the number of accumulated cycles. The damage rate equation is postulated in a generic power law format, which also includes the effect of the load stress-ratio. The material SN curves for pure mode II loading are obtained in closed form by a simple integration of the assumed damage evolution law. The material Delamination propagation rate as a function of the energy release rate and the stress-ratio is similarly obtained combining the aforementioned damage evolution law with a regularized expression for the stress field at the crack tip. Two independent fatigue related parameters are sufficient for describing both the Delamination Onset and its growth. This modelling approach is validated by means of experimental fatigue Delamination data for IM7/8552 carbon fibre/epoxy, demonstrating that the unified modelling strategy is able to describe both fatigue initiation and propagation and the associated effect of the stress-ratio.

Christos Kassapoglou - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of Delamination Onset and growth for AP-PLY composite laminates using the finite element method
    Composites Part A: Applied Science and Manufacturing, 2017
    Co-Authors: Weiling Zheng, Christos Kassapoglou
    Abstract:

    Abstract A recently developed fibre placement architecture, Advanced Placed Ply (AP-PLY), has been shown to have promising damage tolerance characteristics for composite structures. Understanding Delamination creation and growth in such architecture is of particular concern. Approaches to predict Delamination Onset in AP-PLY architectures and to analyse Delamination growth are presented. The recovered interlaminar stresses between layers combined with a maximum stress criterion were used to determine Delamination Onset of simple AP-PLY composite laminates under out-of-plane loads. 2D finite element models with cohesive elements inserted at the interfaces of woven layers were used to evaluate the Delamination initiation and propagation in different woven patterns of simple AP-PLY composite beams. The predictions were compared to results from the stress recovery method and to test results. The parameters of the woven pattern, such as woven angle, number of woven plies, number of straight filling plies, and the location of the woven patterns through the thickness direction, were investigated and shown to have a significant effect on Delamination creation and growth.

  • Prediction of Delamination Onset and growth for AP-PLY composite laminates using the finite element method Part A Applied science and manufacturing
    Composites, 2017
    Co-Authors: Weiling Zheng, Christos Kassapoglou
    Abstract:

    A recently developed fibre placement architecture, Advanced Placed Ply (AP-PLY), has been shown to have promising damage tolerance characteristics for composite structures. Understanding Delamination creation and growth in such architecture is of particular concern. Approaches to predict Delamination Onset in AP-PLY architectures and to analyse Delamination growth are presented. The recovered interlaminar stresses between layers combined with a maximum stress criterion were used to determine Delamination Onset of simple AP-PLY composite laminates under out-of-plane loads. 2D finite element models with cohesive elements inserted at the interfaces of woven layers were used to evaluate the Delamination initiation and propagation in different woven patterns of simple AP-PLY composite beams. The predictions were compared to results from the stress recovery method and to test results. The parameters of the woven pattern, such as woven angle, number of woven plies, number of straight filling plies, and the location of the woven patterns through the thickness direction, were investigated and shown to have a significant effect on Delamination creation and growth.

Stephen R Hallett - One of the best experts on this subject based on the ideXlab platform.

  • simulation of progressive failure in laminated composites under variable environmental conditions
    Materials & Design, 2020
    Co-Authors: Ganapathi Ammasai Sengodan, G Allegri, Stephen R Hallett
    Abstract:

    Abstract This paper presents the development, calibration and finite element implementation of a novel set of phenomenological equations describing the effect of temperature and moisture on the stiffness, strength and toughness properties of fibre-reinforced plastics. An extension of the classical Zhurkov's kinetic approach is proposed to describe the effect of temperature and moisture on the ply-level matrix-dominated strength properties. The phenomenological equations are implemented into a finite-element simulation framework, consisting of a smeared crack approach for modelling intralaminar and translaminar failure, coupled with a bi-linear cohesive zone approach to describe Delamination Onset and progressive growth. The modelling approach is calibrated by means of experimental data in the open literature for the carbon-epoxy material IM7/8552. Validation case studies for the simulation strategy include quasi-isotropic short beam shear coupons and open-hole specimens subject to tension. It is demonstrated that the proposed simulation framework provides a comprehensive quantitative description of the role played by environmental effects in terms of development and interaction of intralaminar, interlaminar and translaminar damage processes.

  • a simplified layered beam approach for predicting ply drop Delamination in thick composite laminates
    Materials & Design, 2016
    Co-Authors: Khong Wui Gan, G Allegri, Stephen R Hallett
    Abstract:

    Abstract The prediction of Delamination Onset is a challenging task in the design of thick tapered composite laminates, where multiple ply terminations (“drop-offs”) are present. This paper addresses the development of a global-local finite element-based design approach for tapered laminates, whereby layered Timoshenko beam models are employed to predict Delamination initiation from individual drop-offs. This modelling strategy provides a fast and conservative method for evaluating the strength of tapered composite laminates. Parametric test cases are presented in order to validate the methodology and understand its limitations. Finally, the application of the tool to a relatively thick tapered composite test specimen comprising multiple ply-drops is demonstrated.

Luc R Leblanc - One of the best experts on this subject based on the ideXlab platform.

  • environmental effects on mode ii fatigue Delamination growth in an aerospace grade carbon epoxy composite
    Composites Part A-applied Science and Manufacturing, 2012
    Co-Authors: Benoit Landry, Gabriel Laplante, Luc R Leblanc
    Abstract:

    Abstract An investigation of the effects of water, hydraulic fluid and deicing fluid exposure on mode II Delamination propagation in an aerospace grade composite is presented. All exposed specimens suffered a loss in Delamination toughness and an increase in fatigue Delamination growth rate , which was particularly significant for deicing fluid exposure. The number of cycles for Delamination Onset was also reduced by these exposures, although scanning electron micrographs showed no significant differences between the fracture pattern of dry and exposed specimens. It was also shown that environmental effects can be simply accounted for in a cohesive zone based finite element model.