Savojni modul elastičnosti drva hrasta u longitudinalnom smjeru

undergraduate thesis

• Title (english): Bending modulus of elasticity of oak wood in the longitudinal direction
• Author: Karlo Strunje
• Mentor: Vera Rede (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-03-01, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Drvo u usporedbi s ostalim materijalima ima karakteristično veliki raspon vrijednosti svojstava. Ti veliki rasponi mogu biti unutar iste vrste, pa čak i samog stabla gdje mogu imati i po desetak puta manju gustoću u nekim dijelovima ili po nekoliko puta veću savojnu čvrstoću, tvrdoću ili krutost. U radu je određen savojni modul elastičnosti za drvo hrasta lužnjaka u longitudinalnom smjeru metodom savijanja u tri točke. Smjer savojne sile bio je okomit na vlakanca kod svih ispitanih uzoraka, a variran je smjer sile u odnosu na tijek godova (0°, 45°i 90°). Savojni modul elastičnosti hrasta lužnjaka u longitudinalnom smjeru vrlo malo ovisi o položaju savojne sile u odnosu na tijek godova. Srednja vrijednost savojnog modula elastičnosti iznosi 17,48 GPa za 0°, 15,82 GPa za 45° i 15,62 GPa za 90°. Vrijednosti i rasipanja rezultata savojnog modula elastičnosti ponašaju se po zakonu Weibullove razdiobe, kojom su statistički analizirani rezultati. Weibullovi dijagrami pokazuju što je veći parametar oblika ili Weibullov modul, to je veća homogenost strukture. Za prvu skupinu Weibullov modul iznosi 8,02, za drugu skupinu 12,56, a za treću skupinu 8,50. Dobivene vrijednosti savojnog modula elastičnosti hrasta lužnjaka nešto su više od vrijednosti koje se za istu vrstu mogu naći u literaturi.

Abstract (english)

Compared to other materials and characteristic to itself, wood has a wide range of property values. Those large ranges can be between the species itself, or even a single tree where they can have a ten times smaller density, bending strenghts, stiffnes or hardness in certain parts. In this paper a flexural modulus of elasticity for the tree of red oak in the longitudinal direction is determined by three - point bending. The direction of the bending force was perpendicular to the fibers in all the tested samples, and the direction of force was varied in relation to the flow of gods. The flexural modulus of the red oak in the longitudinal direction depends very little on the position of the bending force relative to the course of the gods (0°, 45° and 90°). The mean value of the flexural modulus of elasticity is 17.48 GPa for 0°,15.62 GPa for 45°, 15.82 GPa for 90°. Values and dissipations of the bend modulus of elasticity behave according to the Weibull distribution law, which we also use to statistically analyze the results. Weibull diagrams show us that, the bigger the perimeter of a shape or the Weibull modulus, the more homogenic the structure. For the first group Weibull's modulus is 8,02, for the second group 12,56, and for the third group 8,50. By comparing the results of our experiment to the values in the literature we can observe that our experimental samples have a slightly larger elasticity modulus.

• Keywords: savojni modul elastičnosti; hrast lužnjak; Weibullova razdioba
• Keywords (english): flexural modulus of elasticity; the tree of red oak; Weibull distribution
• Language: croatian
• URN:NBN: urn:nbn:hr:235:120550
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 21:47:31