diplomski projekt
Grega Škufca (Author), Gorazd Fajdiga (Reviewer), Sergej Medved (Mentor)

Abstract

Zgradba smuči je zelo kompleksna. Smuči morajo zagotavljati določene lastnosti med katerimi glavno vlogo igrajo togost, trdnost in teža smuči. Vse te lastnosti v veliki meri izhajajo iz same sredice smuči. Za izdelavo vrhunskih smuči se največ uporablja lesena sredica, obstaja pa kar nekaj alternativ: karbonska vlakna, ojačitve iz titanija, itd. Vse bolj pa v ospredje prihajajo kompoziti, katerih osnovni gradniki so naravna vlakna. Konoplja kot najstarejša poljščina vsebuje dolga vlakna, saj se raztezajo vzdolž celega stebla rastline. So izredno močna in predstavljajo odlično naravno alternativo dragim umetnim vlaknom, ki se trenutno uporabljajo pri izdelavi lahkih kompozitov. Za osnovni materijal pri izdelavi plošč smo uporabili dolga konopljina vlakna, kot vezivo pa melamin-urea formaldehidno lepilo. Izdelane plošče smo izpostavili ciklični obremenitvi pri različnih odstotkih maksimalne sile, predhodno določene z upogibnim preizkusom na industrijsko izdelani plošči iz kratkih konopljinih vlaken. Ugotovili smo, da se pri vseh vzorcih opazijo razlike med inicijalno deformacijo in deformacijo po 50. ciklu, odvisno od aplicirane sile. Večje deformacije smo ugotovili pri večjih silah obremenitve, tudi do 15 % nepovratne deformacije. Pri vzorcih, izpostavljenih hladnemu okolju (-15 °C), je pri velikih silah obremenitve med cikličnim preizkusom prišlo do loma preizkušancev. V primerjavi z referenčnimi ploščami smo ugotovili pozitiven učinek uporabe daljših vlaken, saj so bile deformacije pri laboratorijsko izdelanih ploščah nižje kot pri referenčnih. Ugotovili smo tudi razliko med obnašanjem materijala glede na pogoje okolja, v katerem smo imeli izpostavljene vzorce.

Keywords

konopljina vlakna;vlaknena plošča;upogibna trdnost;ciklična obremenitev;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [G. Škufca]
UDC: 633.522:685.363.2
COBISS: 2276233 Link will open in a new window
Views: 398
Downloads: 99
Average score: 0 (0 votes)
Metadata: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Other data

Secondary language: English
Secondary title: Development and production of the core and surface layer of hemp fibre composite for skis
Secondary abstract: The composition of skis is very complex. The skis have to provide certain properties of which rigidity, strength and weight are the most important. All of these properties mostly come from the inner core of the skis. To produce high-quality skis, wood is usually used for the core, along with some other alternatives: carbon fibres, titanium reinforcements, etc. Apart from that, the natural fibre composites are increasingly coming to the forefront. Hemp, the oldest field crop, has long and very strong fibres, located along the whole length of the stem. They present a great alternative to other artificial fibres currently used to form light composites. To make the board, we used long hemp fibres as the basic material, and melamine urea formaldehyde glue as a binder. We then exposed the produced boards to the cyclic load at various percentages of maximum force, determined beforehand by performing a bending test on the industrially manufactured board made from short hemp fibres. We have established that there are differences among the deformations in all of the samples. These occur between the initial deformation and the deformation after the 50th cycle depending on the applied force. Larger deformations were found at higher force loads, up to 15 % of permanent deformation. During the cyclic testing, some of the examined items fractured, when exposed to cold conditions (-15 °C) under high force loads. A positive effect of using longer fibres was noticed, since the deformations of the laboratory-made boards were lower than those in the reference boards. We have also found out the differences in material behaviour depending on the environmental conditions the samples were exposed to.
Secondary keywords: hemp fibre;fibre board;bending strength;cyclic load;
Type (COBISS): Diploma project paper
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za lesarstvo
Pages: VI, 25 f.
ID: 11905783