Detecting damage in high-pressure composite tanks
Proposed methods of inspection for composite tanks are highly labour intensive, requiring the use of expensive equipment to carry out off-vehicle inspection and pressure testing. However, a new approach developed through an EU project can quickly and easily evaluate the structural integrity of a tank during refuelling. The ZEM project developed a monitoring system based on fibre optic sensors for high-pressure tanks made from composite materials. Sensors embedded in the composite material can provide a simple but detailed evaluation of the structural integrity of the tank. The monitoring system is able to detect faults or critical conditions at a very early stage. The consortium successfully developed and tested algorithms for detecting damage which could reduce the burst pressure of the tank below a warning threshold. Researchers predicted that damage to the tank would result in greater flexibility and overall deformation. An additional important feature that required monitoring was the symmetry of the strain field of the tank, which was expected to change in the case of damage. Analysis showed that the sensor layout could detect any cutting and impact damage to the composite tank that would decrease the burst pressure. Defects were identified well before the burst pressure was reached, enabling a swift response to any damage that might threaten the integrity of the tank. The ZEM project's development of fibre optic sensor technology for structural monitoring will enable Europe to compete with the United States in this relatively new field. The technology will help to improve health and safety and facilitate the use of natural gas and hydrogen for vehicles operating using alternative fuels and fuel cells. This will result in lower emissions, as well as energy savings due to the decrease in vehicle weight, since composite tanks are significantly lighter than metal ones.