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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.
Accumulation of Fibre Breaks under Time Dependent Loads in CFRP Materials of Pressure Vessels
(2018)
BAM has discovered that the reliability of tested composite pressure vessel will be altered when the loading speed is varied. The ageing of composite materials in general gives negative effect to the structure, however there might be positive effect occurs due to the load redistribution between the fibres. The study on the negative effect of ageing has been compared favourably with the fibre break model from Mines ParisTech. To improve the model's capability, this positive effect should also be implemented. The problem however to evaluate real scale model that might take extensive computation time. The reduced volume method then was proposed to improve the calculation time. The next study is then to check the approach on different loading condition and compare the result with experimental data provided by BAM.
As a result of the vehicle – infrastructure interaction, both systems deteriorate. The development of performance measures about such effects, is critical to find ways to mitigate these systems deterioration. We propose an energy approach to such an assessment: The transient energy stored in the pavement. The transient strain energy stored in the vehicle suspension.
Die BAM legt als zuständige Behörde die zusätzlichen Prüfanforderungen an die verwendeten Verpackungen/ Großverpackungen nach P 911 und LP 906 fest (Teil A dieser BAM-GGR).
Außerdem kann die BAM gemäß Sondervorschrift 376 davon abweichende alternative Verpackungs- und/oder Beförderungsbedingungen zulassen (Einzelfallfestlegung,Teil B dieser BAM-GGR).
Due to high specific stiffness, fibre reinforced plastics are the dominant material group for the design of mobile pressure vessels. At the Federal Institute of Materials Research and Testing (BAM) aging process of composite pressure vessels is studied to be able to give more accurate lifetime predictions in future. Investigations are based on type III breathing air cylinders consisting of an aluminium tank which is fully wrapped with carbon fibre reinforced plastics. Goal is to detect changes of residual stresses over life time which directly affect fatigue strength. Within this paper an approach is presented to monitor residual stresses via an experimental modal analysis (EMA). First, the influence of changed stress conditions on modal parameters is analysed via a numerical study. Secondly, a test bench for an EMA is set up. To be able to analyse cylinders of different prestress condition, several specimens are prestress modified via high-temperature and high-pressure treatment. During modification processes, specimens are monitored via optical fibres to control prestress modifications. Through experimental measurements of the modified specimens via EMA changes in prestressing can be detected. Finally, validity and accuracy of the EMA is evaluated critically by comparing all numerically and experimentally obtained data.
Due to high specific stiffness, fibre reinforced plastics are the dominant material group for the design of mobile pressure vessels. At the Federal Institute of Materials Research and Testing (BAM) aging process of composite pressure vessels is studied to be able to give more accurate lifetime predictions in future. Investigations are based on type III breathing air cylinders consisting of an aluminium tank which is fully wrapped with carbon fibre reinforced plastics. Goal is to detect changes of residual stresses over life time which directly affect fatigue strength. Within this paper an approach is presented to monitor residual stresses via an experimental modal analysis (EMA). First, the influence of changed stress conditions on modal parameters is analysed via a numerical study. Secondly, a test bench for an EMA is set up. To be able to analyse cylinders of different prestress condition, several specimens are prestress modified via high-temperature and high-pressure treatment. During modification processes, specimens are monitored via optical fibres to control prestress modifications. Through experimental measurements of the modified specimens via EMA changes in prestressing can be detected. Finally, validity and accuracy of the EMA is evaluated critically by comparing all numerically and experimentally obtained data.