Proučevanje trdnosti zobatih spojev lamel slojnatega lepljenega lesa z dinamičnimi testi

Omulec, Matic (author), Straže, Aleš (mentor), Šega, Bogdan (comentor)

Z dinamičnimi testi smo proučevali trdnost zobatih spojev lamel slojnatega lepljenega lesa in jih primerjali z rezultati statičnih testov. Zaradi zakonodaje morajo biti testi trdnosti zobatih spojev redno izvedeni v skladu z zahtevami standarda SIST EN 14080. Test je dolgotrajen in porušen, zato smo preverili, ali je mogoče napovedovati upogibno trdnost z metodo frekvenčnega odziva, ki je neporušna in hitrejša za izvedbo. Dinamični testi so bili izvedeni v prečni in vzdolžni smeri. Potrdili smo, da je modul elastičnosti linearno odvisen od gostote lesa. Potrdili smo tudi, da obstaja povezava med akustičnimi in elastomehanskimi veličinami, določenimi v frekvenčnem odzivu, ter trdnostjo zobatih spojev. Zanesljivost napovedovanja je pri dinamičnih testih nižja kot pri statični togosti. Zanesljivost pri statični togosti je 51 %, med tem ko je pri dinamičnem upogibnem modulu 39 % in pri vzdolžnem modulu elastičnosti 25 %. Ugotovili smo, da samo z dušenjem zvoka in akustičnim koeficientom ne moremo predvidevati upogibne trdnosti. Determinacijski koeficient je pri teh rezultatih bil vedno nižji od 15 %. Pearsonov koeficient za korelacijo upogibne trdnosti in dinamičnega upogibnega modula ter korelacijo upogibne trdnosti in dinamičnega vzdolžnega modula je znašal 0,56 in 0,49, kar je manj kot korelacija upogibne trdnosti s statičnimi testi (0,71). To pomeni, da rezultati pridobljeni z dinamičnimi testi niso zadosten pokazatelj trdnosti.

• Language: Slovenian
• Keywords: les, slojnat lepljen les, zobati spoji, preizkušanje, dinamični testi, statični testi
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [M. Omulec]
• Year: 2018
• PID: 20.500.12556/RUL-103322
• UDC: 630*812.7
• COBISS.SI-ID: 2944905
• Publication date in RUL: 16.09.2018

Secondary language

• Language: English
• Title: Study of the bonding strength of glulam finger joints by mechanical dynamic testing

Abstract

Using the dynamic tests we studied the bonding strength of glulam finger joints and compared them to the static test results. Due to the legislation, the tests for bonding strength of glulam finger joints must be regularly carried out with demands of the SIST EN 14080 standard. Because of the long-lasting and destructive characteristics of the test we checked, if we were able to predict bonding strength using the frequency response method which is faster and non-destructive. The dynamic tests were performed both in transverse and longitudinal direction of finger jointed lamellas. We confirmed that the modulus of elasticity is changing linearly with density of wood. We also confirmed the correlation between acoustic and elastomechanical properties, determined in frequency response and glulam finger joint strength. Reliability of predicting the bonding strength is smaller using dynamic tests than with static test. Reliability with static test is 51% whereas with the dynamic bonding strength, the reliability is 39% and 25% with longitudinally modulus of elasticity. We found that only with the damping of sound and the acoustic coefficient we cannot predict the bending strength of finger jointed glulam lamellas. Determination coefficient was always lower by 15% considering these results. Pearson's coefficient for correlation between bonding strength and dynamic bending modulus and between dynamic longitudinally modulus is 0.56 and 0.49 which is less than the correlation between bonding strength and static tests (R2 = 0.71). This means that the results obtained with dynamic tests are not sufficient in determining the bonding strength.

• Keywords: wood, glulam, finger joints, testing, dynamic tests, static tests