PT  - JOURNAL ARTICLE
AU  - Průša, Filip
AU  - Jonák, Vít
AU  - Strakošová, Angelina
AU  - Doubrava, Karel
AU  - Španiel, Miroslav
AU  - Vystrčil, Václav
AU  - Vojtěch, Dalibor
TI  - Identification of the cause of damage to the firefighter ladder
DP  - 2020 Dec 8
TA  - Manufacturing Technology Journal
PG  - 500--506
VI  - 20
IP  - 4
AID - 10.21062/mft.2020.068
IS  - 12132489
AB  - Two extendable firefighter ladders, both made of AA 6063 alloy, has been destructively tested accord-ingly to the ČSN EN ISO 1147 to determine the maximal load before their failure. For this purpose, two brand new ladders with a complex profile were compared to the 5-year old one with a far simpler profile. It was found, that the new ladder broke already at a load of 366 (365 kg) while the 5-year old ladder could withstand a much higher load of 426 kg. Since both the ladders broke nearby the guides acting as a mechanical support for their extension, it was of high interest to investigate the cause of different behaviour. Considering the fact, that the brand new ladder had a much more complex pro-file of the beam and the fact, that the guides were welded to the beams, it was of high importance to investigate the influence of the weld on the overall integrity of the ladder. It was found, that the weld itself deteriorated the mechanical properties of the beam reaching the minimal hardness in the dis-tance of 10 mm, which also corresponded with the crack initiation site. This place also showed the lowest hardness reaching only 52 HV 1.