Pine sapwood dynamic and static modulus of elasticity comparison on different moisture levels

Käesolevas bakalaureusetöös on uurimise all puidu niiskus, ultraheli kiiruse levimine puidus ja paindetugevuse mõõtmine. Töö eesmärk on leida, kuidas muutuvad puidu, täpsemalt männi maltspuidu, omadused niiskuse vähendamisel. Kasutatud on V-meter mark IV ultrahelikiiruse mõõteseadet, Instron 3369 paindetugevuse mõõteseadet ja ka erinevaid kuivatuskambreid. Katsed sooritati kahekümne neljal männi maltspuidust koosneval klotsil, mõõtudega 270 mm x 20 mm x 20 mm. Klotsid jaotati nelja gruppi: esimene grupi klotsidel tehti mõõtmised algkaalus, teises grupis olid klotsid, kust kuivatati umbes 10 grammi vett, kolmanda grupi klotsidest umbes 20 grammi vett ja neljandas grupis olevatest klotsidest umbes 30 grammi vett. Selle tulemusel muutusid klotside niiskusprotsendid ja erinevate niiskustasemete puhul muutusid ka klotside tehnilised näitajad. Töö tulemusega selgub, et niiskuse muutudes puidus saab võrrelda tema staatilisi ja dünaamilisi näitajaid. Samalaadsetes uuringutes on ka varem saadud sarnaseid tulemusi.This thesis has been under investigation for moisture, ultrasonic propagation velocity of the wood and bending strength measurements. The work aims to find out how does wood , specifically pine sapwood, properties differ after drying water from it. V-meter mark IV ultrasonic velocity measurement was used, Instron 3369 testing machine for compression, and a variety of drying chambers. Experiments were performed on twenty-four pine sapwood blocks, measuring 270 mm x 20 mm x 20 mm. Blocks were divided into four groups, the first group had the blocks in their initial weight, the second group had the blocks, which lost about 10 grams of water due to drying, the third group had blocks which were dried about 20 grams lighter, and the fourth group of blocks, that had been dried about 30 grams lighter. As a result the moisture percentages changed as a result different humidity levels changed the technical properties of the blocks. The work shows that one can compare woods’ static and dynamic characteristics at its’ different moisture levels. Similar studies have previously received a similar outcome