Determination of Strength Characteristics of Construction Timber Strengthened with Carbon and Glass Fibre Composite Using a Destructive Method
Beams strengthened with a composite material consisting of carbon and glass fibre stabilised with two types of adhesives were evaluated. The primary objective was to determine the technical attributes of joints, the maximum bending strength capacity, deflection, and modulus of elasticity. The reinforcement fibres tested were based on carbon and glass fibre. Epoxy and polyurethane adhesives were used for stabilising the fibres on a spruce timber beam. Composite beams glued in both a prestressed and non-prestressed condition were tested and then compared with non-reinforced control beams. A four-point deflection pursuant to EN 408 (1995) was used in the determination of the strength of the load-bearing construction beams based on composites, consisting of a fibre type, adhesive type, and spruce timber. This approach was applied to define the size of the construction beams and process the measurement results. Reinforcing construction beams with fibres applied in a prestressed condition resulted in an increase in the bending strength capacity by 31.6 to 44.4% compared with a non-reinforced solid timber construction beam. These construction elements, strengthened with carbon and glass fibre composites glued with epoxy and polyurethane adhesives, are suitable for applications that require bending resistance perpendiculary to the glued joint direction.
Karbon fiber ve cam fiber ile güçlendirilmiş ısıl işlem uygulanmış lamine kaplama kerestelerin (lvl) bazı fiziksel ve mekaniksel özellikleri
Ahşap, yaygın olarak kullanılan en eski yapı malzemelerden birisidir. Farklı alanlarda da farklı amaçlarla kullanımına yönelik giderek artan bir talep vardır. Bu talebi karşılayabilmek için ahşap esaslı yapısal kompozitler geliştirilmiştir. Bu çalışmada, ısıl işlem uygulanmış ve fenol formaldehit (FF) tutkalı kullanılarak karbon ve cam elyaf ile güçlendirilmiş kayın (Fagus orientalis Lipsky) kompozit örneklerin bazı fiziksel ve mekaniksel özellikleri araştırılmıştır. Bu amaçla ahşap malzemelere 150, 175 ve 200°C sıcaklıkta 3 saat süre ile ısıl işlem uygulanmış ve deney örnekleri hazırlanmıştır. Test sonuçları, karbon ve cam elyaf ile güçlendirilmiş örneklerin eğilme direnci (MOR) ve eğilmede elastikiyet modülü (MOE) değerlerini artırdığını göstermiştir. Bununla birlikte liflere paralel basınç direnci (CS//) değerlerinde, uygulanan ısıl işlem sıcaklığına ve güçlendirici malzeme türüne göre önemli değişikliklere neden olurken, liflere paralel yapışma direnci (SS) değerlerinde düşüşler belirlenmiştir. Genel olarak, karbon fiber ile güçlendirilmiş deney örneklerin MOR ve MOE değerleri, cam elyaf ile güçlendirilmiş örneklerden daha yüksek, CS// ve SS değerleri ise daha düşük belirlenmiştir.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.