Varijabilnost savojnih svojstava tikovine u longitudinalnom smjeru

master's thesis

• Title (english): Variability of bending properties of teak wood in the longitudinal direction
• Author: Ela Čondrić
• Mentor: Vera Rede (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2023-12-07, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

U diplomskom radu istraženo je kako na savojni modul elastičnosti i savojnu čvrstoću tikovine u longitudinalnom smjeru, utječe kut između savojne sile i tangente na god. Savojna čvrstoća i savojni modul elastičnosti ispitani su metodom savijanja u tri točke. Optičkom mikroskopijom i računalnom tomografijom analizirana je mikrostruktura tikovine u poprečnom, radijalnom i tangencijalnom presjeku.
Potvrđeno je da tikovina ima prstenasto poroznu mikrostrukturu. Gustoća tikovine iznosila je 0,67 g/cm3 uz udio vlage od 6,56 %.
Utvrđeno je da kut između savojne sile i tangente na god utječe na vrijednosti savojnog modula elastičnosti i savojne čvrstoće u longitudinalnom smjeru. Najviše vrijednosti izmjerene su kod kuta od 90°, a najniže kod kuta od 0°. Vrijednosti savojnog modula elastičnosti nalaze se u rasponu od 13,28 GPa do 14,77 GPa, a vrijednosti savojne čvrstoće u rasponu od 138,53 MPa do 151,41 MPa. Koeficijent varijacije za savojni modul elastičnosti je u dopuštenim granicama, a za savojnu čvrstoću prelazi normom dopuštene vrijednosti. Rezultati su dobro opisani Weibullovom razdiobom, a najveći Weibullov modul je kod uzoraka gdje je kut između savojne sile i tangente na godove 45°. Koeficijent korelacije za sve kutove je viši od 0,97.

Abstract (english)

In this thesis, it was investigated how the bending modulus of elasticity and bending strength of teak in the longitudinal direction is affected by the angle between the bending force and the tangent to the annual ring. Bending strength and bending modulus of elasticity were tested using the three-point bending method. The microstructure of teak in cross, radial, and tangential section was analyzed by optical microscopy and computed tomography.
It has been confirmed that teak has a ring-porous microstructure. The density of teak was 0.67 g/cm3 with a moisture content of 6.56%.
It was found that the angle between the bending force and the tangent to annual ring affects the values of the bending modulus of elasticity and bending strength in the longitudinal direction. The highest values were measured at an angle of 90°, and the lowest at an angle of 0°. The bending modulus values are in the range from 13.28 GPa to 14.77 GPa, and the bending strength values are in the range from 138.53 MPa to 151.41 MPa. The coefficient of variation for the bending modulus of elasticity is within the permissible limits, and for the bending strength it exceeds the permissible values. The results are well described by the Weibull distribution, and the largest Weibull modulus is found in samples where the angle between the bending force and the tangent to the grain is 45°. The correlation coefficient for all angles is higher than 0.97.

• Keywords: savojni modul elastičnosti; savojna čvrstoća; tikovina; Weibullova razdioba
• Keywords (english): bending modulus of elasticity; bending strength; teak; Weibull distribution
• Language: croatian
• URN:NBN: urn:nbn:hr:235:335546
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-12-06 10:45:08