Določanje mehanskih lastnosti lepilnih spojev v bukovini z nedestruktivnimi metodami

magistrsko delo

Martin Capuder (Author), Milan Šernek (Reviewer), Aleš Straže (Mentor), Boris Azinović (Co-mentor)

Abstract

V raziskavi smo pri lepljenju bukovine, na podlagi razcepnega in tri-točkovnega preizkusa, dopolnjenega z dinamičnimi mehanski testi ter analizo akustične emisije (AE), vrednotili vpliv obdelave površine, orientiranosti in vlažnosti lesa na mehanske lastnosti lepilnih spojev. Del preizkušancev smo proučevali pri nižji (ur1 = 12 %) in višji ravnovesni vlažnosti (ur2 = 18 %), ter tudi umetno pospešeno starali (UPS). Lepilni spoji z brušeno površino so v vseh preizkusih dosegli najboljše rezultate. Ugotovili smo, da povišana vlažnost lesa negativno vpliva na mehanske lastnosti lepilnih spojev. Na skobljani površini smo pozitivni vpliv predpremaza, z izračunano višjo energijo pri lomu, potrdili le v razcepnem preizkusu. Nehomogena sestava preizkušancev, je zaradi različne usmerjenosti lesnega tkiva v prečnem prerezu lamel negativno vplivala na mehanske lastnosti lepilnih spojev, tudi po postopku umetno pospešenega staranja. Umetno pospešeno staranje je v lamelah in lepilnih spojih povzročilo strukturne napake, in zmanjšalo število ustreznih preizkušancev, zaradi česar vpliva postopka ni bilo mogoče izvrednotiti. Pri staranih preizkušancih smo zaznali povišan čas preleta ultrazvoka skozi lepilni spoj, kar pa ni bilo neposredno povezano z rezultati statičnih mehanskih preizkusov. Z metodo frekvenčnega odziva smo pri vzdolžnem vzbujanju določili vzdolžni modul elastičnosti za bukovino. Pri prečnem vzbujanju pa smo z isto metodo potrdili korelacijo med dinamičnim (EB') in statičnim (ES') navideznim modulom elastičnosti preizkušancev.

Keywords

les;lepilni spoj;staranje;statično testiranje;nedestruktivne metode;

Data

Language:	Slovenian
Year of publishing:	2023
Typology:	2.09 - Master's Thesis
Organization:	UL BF - Biotechnical Faculty
Publisher:	[M. Capuder]
UDC:	630812.7:630824.7
COBISS:	166565379
Views:	30
Downloads:	2
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Determination of the mechanical properties of adhesive joints in beech wood using non-destructive methods
Secondary abstract:	In this study, the effects of the surface treatment, orientation, and moisture content of wood on the mechanical properties of adhesive bonded joints were evaluated in beech wood using double cantilever beam mechanical tests (DCB) and end-notch flexure mechanical tests supplemented by dynamic mechanical tests and acoustic emission analysis (AE). A portion of the specimens were tested at lower (EMC1 = 12%) and higher equilibrium moisture content (EMC2 = 18%), and also subjected to artificially accelerated ageing (UPS). The glue joints with a sanded surface obtained the best results in all tests. We found that the mechanical properties of the adhesive joints were negatively affected by the increased moisture content of the wood. In the case of the planed surface, the positive influence of using a primer before bonding was confirmed by a calculated higher fracture energy only in the DCB test. The inhomogeneous composition of the test specimens, due to the different orientation of the wood tissue in the cross-section of the lamellae, had negative effects on the mechanical properties of the bonded joints even after the UPS process. The UPS process caused structural defects in the lamellae and glue joints and reduced the number of suitable test specimens, so the effects of the process could not be quantified. A prolonged ultrasonic time of flight through the adhesive joint was observed in the aged specimens, but this could not be directly related to the results of the static mechanical tests. The longitudinal modulus of elasticity for beech wood was determined using the vibration resonance method in the longitudinal direction. The same method was used for the bending mode to confirm the correlation between the apparent dynamic (EB') and static modulus of elasticity (ES’).
Secondary keywords:	wood;adhesive bonded wood;aging;static mechanical test;nondestructive test;
Type (COBISS):	Master's thesis/paper
Study programme:	0
Embargo end date (OpenAIRE):	1970-01-01
Thesis comment:	Univ. v Ljubljani, Biotehniška fak., Oddelek za lesarstvo
Pages:	1 spletni vir (1 datoteka PDF (XI, 56 str., [6] str. pril.))
ID:	19945544