Frangibility analysis and requirements

According to Doc. 9157 AN/901 part 6 from International Civil Aviation Organization (ICAO) a proper design and installation of visual and non-visual aids are prerequisites for the safety and regularity of civil aviation. All such equipment and their supports shall be frangible to assure that impact will not result in loss of control of the aircraft.

A frangible structure should be designed to withstand the static and operational wind or jet blast loads with a suitable factor of safety but should break, distort or yield readily when subjected to the sudden collision forces of a 3000 kg aircraft airbone and travelling at 140 km/h or moving in the ground at 50 km/h.

The frangibility of the design should be proven either by means of full-scale test, computer evaluations or by calculations based on comparison with similar already approved structures possibly supported by additional component tests. One approach to analytical modelling of the impact uses successful commercially available finite element analysis (FEA) programmes. Explicit non-linear FEA programmes are used for impact analysis and large deformation, because of their ability to continue analysis after predicted “fracture” of elements that comprise the model.

Thanks to the experience acquired, TEAMS is able to offer its customers a combination of solutions that enable them to comply with current regulations, having available the necessary equipment to perform both experimental tests and analytical models to efficiently evaluate the frangibility of almost any structure.