Visit to NASA Langley Research Center - participation in the second World Wide Failure Exercise

Lead Research Organisation: Imperial College London
Department Name: Aeronautics


The work to be carried out during this visit will result in a complete set of predictions for the several test cases of the second World Wide Failure Exercise (WWFE II)*. The different test cases of the exercise have different levels of difficulty, will involve different areas of our failure theories, and might require different implementations of it. For this reasons, the readiness level of any preliminary predictions by July (before the visit) will vary substantially from test case to test case. The visit will start by organising the preliminary predictions according to readiness level. Starting from the test cases for which the predictions are understood to be closer to be finalised (higher readiness level), each prediction will be reviewed in detail, and the final predictions will be defined. It is likely that the test cases with lowest readiness level will correspond to no preliminary predictions available at the start of the visit. For these cases, a much greater amount of effort and time will be required before a final prediction is defined and agreed. Finally, tables and graphs will be generated in the format required by the organisers of the WWFE II, as well as the corresponding research paper with the theory employed and its application to the test cases of the WWFE II.During the visit, and in parallel with the work on the WWFE II, there will be discussions on strengthening future collaborations between Imperial College London and NASA. The two routes which will be exploited are (i) funding sources for joint research projects, and (ii) including NASA researchers as consultants/ collaborators in British and European grants. Regarding the latter, it is already being considered in a grant to be submitted to EPSRC in the near future.*The WWFE II is a benchmarking exercise aimed at establishing the current knowledge and predictive capability in failure of composites reinforced with UD plies under a generic three-dimensional (3D) state of stress. Only selected proposers of recognised failure theories were invited to participate in the exercise, and amongst them is our team, comprising Imperial College London, NASA and the University of Porto. This selection is an important recognition of the failure theories published by our group. Following with the tradition of the first exercise (WWFE I), this second exercise will give a high visibility to the failure theories of the participants, and advance the knowledge on failure of composites. The exercise comprises two parts: in a first part, the participants are asked to carry out blind predictions for failure envelopes involving a 3D stress state, and publish their results; in the second part, the participants are given the experimental results, and are asked to comment on the correlation of their predictions with the experimental results, and propose any amendments to their theories if appropriate. The deadline for the first part is end of November 2007, and our team is already working on generating failure envelopes for some of the test cases.
Description We prepared our participation in WWFE-II, which we won.
Exploitation Route Failure models can be used directly or in FE packages.
Sectors Aerospace

Defence and Marine

Leisure Activities

including Sports

Recreation and Tourism


including Industrial Biotechology


Description They were used to participate in the WWFE-II, in which we came first
First Year Of Impact 2013
Sector Aerospace, Defence and Marine,Leisure Activities, including Sports, Recreation and Tourism,Manufacturing, including Industrial Biotechology,Transport
Impact Types Cultural



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).