These experiments will require detailed planning involving modelling to ensure that the required in-service moisture profiles are achieved. The results of the moisture uptake tests will provide the data necessary to determine models which can predict the moisture uptake patterns of the materials in the tee joints for different temperature and humidity levels over time. In some cases, the Fickian model can be used to determine the diffusion parameters and this has already been achieved with some success using previously obtained data. In others, particularly the foams, other existing models may be used or specific ones developed. The uptake tests have been under way since early 1998 but saturation has not yet been reached in some of the materials.
Further data is required before a full analysis can be undertaken.
Some finite element modelling of the joints has been conducted which has been compared directly with the calibrated thermoelastic data, with reasonable success. Further analyses are being undertaken at present to explore various geometrical and manufacturing variations and obtain detailed information about the stresses and load transfer mechanisms within the joints. This work will be extended further to include environmental effects, enabling the influence of combined environmental ageing and mechanical loading to be investigated theoretically, leading ultimately to the development of a model which can be calibrated using the experimental results and applied to larger composite structures.