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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.
A high resolution micro-CT scan of a hoop layer from type IV cylinder has been carried out. The directional Gradient function had been used to analyse the in-plane and out-of-plane fibre misalignment from the Micro-CT Images. A correlation Analysis of the directional Gradient has also been performed and compared with the existing results from the cited paper.
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.
This presentation explains how the evaluation of technical requirements in regulations effects safety level. This shown by using the Monte-Carlo experiment consequently.
The first step is to explain how deterministic requirements and how probabilistic requirements work. Then the statistical behaviour of the generally unknown basic population can be described and that his behaviour is independent from the regulatory approach. Subsequently, the concept of evaluating sample test results with respect to deterministic requirements is explained. The item “acceptance rate” of the basic population that is behind each sample and behind each individuum in a sample is defined. On this collective understanding, the differences in evaluation between the probabilistic approach PA and the most important RC&S are discussed. Some areas are validated in contradictorily. Then the parameters for acceptance of burst strength in the UN-GTR#13 are varied and opens the door for an accurate improvement of acceptance criteria. Finally, the special aspects of degradation in load cycle testing are shown. There, two aspects must be differentiated, the current reliability and its degradation by ongoing load cycles. This is a convincing argument against the very common opinion, which means that the number of hydraulically tested load cycles pro-vides a figure for the number of acceptable filling cycles.