Volume 16, No. 3

Authors: Nikonov, Anatolij; Burnik, Stojan; Emri, Igor

Examination of the time-dependent behaviour of climbing ropes under impact loading

Preiskava časovno odvisnega vedenja plezalnih vrvi pri impulznih obremenitvah

Abstract (English)

A recently developed experimental-numerical-analytical methodology, based on a simple non-standard falling weight experiment, allows the calculation of several physical quantities that are important for the safety of a climber, such as: the maximum force acting on the rope; jolt, i.e., the derivative of the (de)acceleration; the maximum deformation of the rope; and modification of the stiffness of the rope within each loading cycle. This methodology was used in the mechanical characterisation of three commercial climbing ropes. The results indicate that ropes which according to the existing UIAA standard belong to the same quality class actually exhibit significantly different behaviour when exposed to the same loading conditions. One of the tested ropes exceeded the critical jolt value (120g/s) already during the second fall. Thus, although it satisfies the requirements of the EN 892 standard, this rope may not be considered safe. The results prove that the existing safety standards need to be reconsidered.

Keywords (English)

climbing ropes, maximum force, jolt, viscoelasticity

Abstract (Slovenian)

Novo razvita eksperimentalno-numerično-analitično metoda, zasnovana na analizi mehanskega odziva vrvi na obremenitev generirano s prostim padom uteži, omogoča določitev večih fizikalnih veličin, ki opredeljujejo varnost plezalca: ujemno silo, spremembo pospeška (pojemka), maksimalno deformacijo vrvi, ter spremembo togosti vrvi v enem ciklu obremenitve. Izračuni mehanskih lastnosti treh tipov vrvi so primerjani med seboj z uporabo novo razvite metode. Predstavljeni rezultati kažejo, da se časovno odvisne lastnosti vrvi, ki v skladu s standardom UIAA sodijo v isti kakovostno-varnostni razred, dejansko med seboj močno razlikujejo. Pri eni izmed preizkušenih vrvi je sprememba pojemka presegla kritično vrednost 120g/s že pri drugi obremenitvi. To vrv, kljub temu, da izpolnjuje zahteve standarda EN 892, ne moremo označiti kot varno. Predstavljeni rezultati potrjujejo potrebo po spremembi obstoječih standardov za zagotavljanje varnosti plezalcev.

Keywords (Slovenian)

plezalne vrvi, ujemna sila, sprememba pospeška, viskoelastičnost

Complete article in PDF format

complete article