Development of failure models and criteria for laminated composites
Lead Research Organisation:
Imperial College London
Department Name: Aeronautics
Abstract
The potential of composite materials as structural parts is currently hindered by our lack of ability to both understand and predict failure initiation and propagation. Developments in this area can lead to faster and more economical design, as well as lighter and more efficient structures. This project will contribute to the capability of predicting failure of laminated composites consisting of unidirectional plies, by focusing on (i) experimental characterisation of each failure mode, (ii) analytical interpretation of the failure mechanisms and (iii) development of numerical simulation tools for failure propagation.The experimental investigation into each failure mode will be particularly detailed, focusing on the qualitative and quantitative description of the sequence of events leading to each failure mode and their interaction. These events take place initially at a micromechanical scale, and then progressively grow to cause structural failure. An example of this is fibre compressive kinking. The kink bands observed in failed composites are the outcome of a sequence of events which include matrix cracking, fibre-bending failure and eventually fibre micro-buckling, and are dependent on fibre misalignments and matrix nonlinear behaviour in shear. Within these events, matrix cracking for instance, is itself the result of the growth and coalescence of matrix micro-cracks. The experimental investigation aims at producing extensive, detailed, univocal information on these processes. It will require design of test rigs, and will make use of intensive instrumentation (e.g. acoustic emission, photogrammetry and strain gauges) as well as optical and scanning-electron microscopy.The experimental findings will be the basis for the development of analytical models describing the sequence of physical events leading to failure and their interaction. These analytical models will form a physical, mechanist, interpretation of each failure mode. They can be understood as a physical theory for each failure mode, translating the observed events into mathematical expressions involving material (e.g. elastic, strength, toughness) and geometric (e.g. fibre diameter, typical fibre misalignments magnitude and distribution, typical matrix micro-cracks size and distribution) properties. The outcome of these models will be a set of equations, which will be expressed as failure criteria, for direct use in design.For the accurate analysis of complex structures, numerical models have to be considered. For this reason, an advanced numerical failure model including the previous failure criteria will be developed, to be used within commercial finite elements software. In order to accurately model failure propagation and avoid spurious mesh dependency, the numerical model will be based on a to-be-developed smeared-crack methodology appropriate for the variety of issues of failure in laminated composites. These have to do with the multiple failure modes composites can exhibit and how each failure mode affects the material response. For instance, matrix cracking will result in the shear components of the traction vector on the fracture plane being reduced to zero, as well as the normal component if positive; the computational model should be able to reproduce this accurately, as well as correctly accounting for the fracture energy of the process. Finally, the numerical model will be validated against experimental data obtained for this effect during the project as well as published in the literature.
People |
ORCID iD |
Silvestre Pinho (Principal Investigator) |
Publications
Pinho S
(2012)
On longitudinal compressive failure of carbon-fibre-reinforced polymer: from unidirectional to woven, and from virgin to recycled
in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Pinho S
(2013)
Material and structural response of polymer-matrix fibre-reinforced composites: Part B
in Journal of Composite Materials
Pinho S
(2013)
Response and damage propagation of polymer-matrix fibre-reinforced composites: Predictions for WWFE-III Part A
in Journal of Composite Materials
Pimenta S
(2009)
A micromechanical model for kink-band formation: Part I - Experimental study and numerical modelling
in Composites Science and Technology
Pimenta S
(2009)
A micromechanical model for kink-band formation: Part II-Analytical modelling
in Composites Science and Technology
Gutkin R
(2011)
A finite fracture mechanics formulation to predict fibre kinking and splitting in CFRP under combined longitudinal compression and in-plane shear
in Mechanics of Materials
Gutkin R
(2011)
On acoustic emission for failure investigation in CFRP: Pattern recognition and peak frequency analyses
in Mechanical Systems and Signal Processing
Gutkin R
(2010)
Micro-mechanical modelling of shear-driven fibre compressive failure and of fibre kinking for failure envelope generation in CFRP laminates
in Composites Science and Technology
Gutkin R
(2010)
On the transition from shear-driven fibre compressive failure to fibre kinking in notched CFRP laminates under longitudinal compression
in Composites Science and Technology
Description | Better failure criteria for composites, particularly for the fibre kinking failure mode |
Exploitation Route | They might be used through material subroutines for FE packages. |
Sectors | Aerospace, Defence and Marine,Leisure Activities, including Sports, Recreation and Tourism,Manufacturing, including Industrial Biotechology,Transport |
URL | http://wwwf.imperial.ac.uk/aeronautics/research/pinholab/ |
Description | Failure criteria have been the basis of further research by bother researchers, and have also been implemented into FE codes |
First Year Of Impact | 2009 |
Sector | Aerospace, Defence and Marine,Leisure Activities, including Sports, Recreation and Tourism,Manufacturing, including Industrial Biotechology,Transport |
Impact Types | Economic |
Description | abc: multiscale Analysis of Bonded Composite Structures |
Amount | £398,243 (GBP) |
Organisation | Airbus Group |
Sector | Academic/University |
Country | France |
Start | 10/2009 |
End | 09/2012 |
Description | iComp: Integrated method for structural design of composite structures |
Amount | € 170,000 (EUR) |
Organisation | Airbus Group |
Sector | Academic/University |
Country | France |
Start | 10/2009 |
End | 09/2012 |
Title | Computer models for failure of composite materials |
Description | This model consists of: - several new failure criteria based on physical observations of different failure modes in composites - a new smeared crack approach to model failure propagation - a new pressure-dependent constitutive law. |
Type Of Material | Computer model/algorithm |
Provided To Others? | No |
Impact | 2nd World-Wide Failure Exercise. In this exercise, world-leading experts were asked to use their theories to provide blind predictions for a comprehensive array of benchmark cases for fail- ure of composites. The theories, and their proposers, were then ranked in two lists corresponding to 'quantitative' and 'qualitative' merit. The blind predictions of the team STP led ranked the highest in both lists. See AS Kaddour and MJ Hinton, "Maturity of 3D failure criteria for fibre- reinforced composites: Comparison between theories and experiments: Part B of WWFE-II", Journal of Composite Materials 2013 47(67) 925966, DOI: 10.1177/0021998313478710). |
Description | AIRBUS OPERATIONS LIMITED |
Organisation | Airbus Group |
Country | France |
Sector | Academic/University |
PI Contribution | STP's failure models used extensively by Airbus: "We've been collaborating with Dr Pinho over a number of years on the development of models for failure of composite structures. This is a very challenging area and these models constitute a positive contribution to our capability to predict damage in large components." (Dr Morten Ostergaard, Airbus Senior Expert in Structure Modelling and Non-Linear Finite Element Analysis, Morten.Ostergaard@Airbus.com) |
Collaborator Contribution | Airbus provided funding, test cases and industrial context. |
Impact | 1. STP's failure models used extensively by Airbus: "We've been collaborating with Dr Pinho over a number of years on the development of models for failure of composite structures. This is a very challenging area and these models constitute a positive contribution to our capability to predict damage in large components." (Dr Morten Ostergaard, Airbus Senior Expert in Structure Modelling and Non-Linear Finite Element Analysis, Morten.Ostergaard@Airbus.com) 2. Several papers are the result of funding from Airbus. |
Start Year | 2007 |
Description | Renault F1 Team Limited |
Organisation | Renault F1 Team Limited |
Country | United Kingdom |
Sector | Private |
PI Contribution | Developed failure models |
Collaborator Contribution | Provided funding and industrial constraints |
Impact | Papers |
Start Year | 2006 |