Challenges and objectives
The major obstacles to the rapid democratisation of hydrogen through means of transport remain the additional costs of the vehicle when purchasing it, as well as of hydrogen when recharging. Batteries and hydrogen constitute two complementary technological bricks. Combined, they can cater for a wide variety of use by parameterising the battery capacity, the power of the fuel cell, and the capacity of the hydrogen tanks (possible architectures: range extender, mid-power, full power).
One of the key factors in the additional cost of the hydrogen vehicle is found in the hydrogen storage. In an effort to reduce weight, metal tanks (type I and type II) have given way to composite tanks.
The issue of fatigue dimensioning is important because it makes it possible to optimise the complete system to obtain the best compromise between weight reduction and reliability, while respecting existing criteria, or the requirements associated with the vehicle architecture.
The methodology developed by our teams integrates know-how in the field of fatigue characterisation and testing of materials, as well as knowledge of the mechanical and vibratory stresses applied to these systems.
These two aspects contribute to the optimisation of the simulations in order to ensure a test/computation correlation and to estimate the optimal lifetime of the system upstream of the testing.
- In-vehicle systems and components
During cyclic thermomechanical loading, Type III tanks are limited by the liner material. As for type IV tanks, their liners are less impacted by pressure, they are however subject to creep and to the polymer aging phenomenon.
- Support and retention brackets
The stresses these systems encounter must be known in order to perform the fatigue analysis. These are totally dependent on the choice of integration of the system into the vehicle architecture.
- Validation by calculations and testing of the structural strength of composite tanks and retention systems (Bracket)
- Optimisation of the filament winding process (geodesic, non-geodesic, axisymmetric delta)
- Minimisation of mass and industrialisation costs while respecting the constraints of thermomechanical resistance
- Development of internal validation and fatigue analysis methodologies
- Support for dimensioning chassis links by multidisciplinary optimisation
- Characterisation of materials (thermomechanical behaviour, S-N curves, creep behaviour)
- Implementation and qualification of tests in subsystems
- Evaluation of fibre/interfibre breaks and delamination phenomenon
- Advanced modelling of key equipment
- Identification of load spectra (real conditions, test track, multi-body modelling)
- Assessment of damage levels and definition of safety factors
Keywords: composite hyperbaric hydrogen storage tank, hydrogen fuel cell vehicles, commercial vehicles (light utility, medium and heavy duty truck), safety, crash, fatigue, durability, finite element simulation.
Tools: ALTAIR Hyperworks, Ansys, Magna FEMFAT, Catia V5