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The reduced volume method has found a particular zone to be used for evaluating the strength of unidirectional composite materials. To validate the method, modelling an experimental test where it has the same basic assumption of the model had been carried out. The result was favourable as the model can predict the average value from the experiment and also the time dependent effect.
A general explanation of reduced volume method was introduced. This has allowed the simulation runs much faster without compromising the failure prediction of the multiscale fibre break model. The validation results with a material samples were shown. A certain mesh configuration to evaluate the cylinder has also been found to be the most effective in terms of computation time and prediction accuracy.
The reduced volume method has been studied using the fibre break model from Mines ParisTech. This method allows less 3D finite elements to be used for predicting the failure of real scale composite structures. A favourable comparison results with racetrack specimens has been achieved. However, the comparison study with a type IV pressure vessels still requires more Evaluation.
Based on the burst test results conducted at BAM, loading rates will affect the strength of composite pressure vessels (CPV). The multiscale fibre-break model developed at Mines ParisTech is able to described this behaviour explained by the stress relaxation in the viscoelastic matrix. The experiment showed an increase of burst pressure when an extreme slow loading rate is used compare to the slow loading rate. Is is then discovered that the model could predict well for the slow loading rate but not for the extreme slow loading rate. It may have something to do with the fibre re-orientation of the hoop layer during the extreme slow loading rate test. Further investigation is required to discover this hypothesis.
The effect of different Weibull parameter from different carbon fibres to predict the failure of a type IV pressure vessel has been analysed. In addition, the effect of the shape and scale parameter has also been done. T700S fibres gave higher burst pressure prediction as it has higher scale parameter and higher stiffness of the fibres. When smaller scale parameter is introduced, lower burst pressure prediction was found and vice versa. Whereas, higher burst pressure prediction was observed when smaller shape parameter was used and vice versa. The latter must have something to do with the higher probability of stronger and weaker fibres in the smaller percentile.
The stacking sequence of a real scale type IV pressure vessels has been found. Feasibility study of a multiscale model has been carried out by modifying the original stacking sequence. All of the results were displayed in a Sample Performance Chart (SPC), where different burst pressure in terms of mean and scatter had been found.