Evaluation of Tensile Strength of a Eucalyptus grandis and Eucalyptus urophyla Hybrid in Wood Beams Bonded Together by Means of Finger Joints and Polyurethane-Based Glue

Abstract

Created in the 1940s, the splice finger-joint type for wood has now been more used to compose structural materials wood base as Glued Laminated Timber (Glulam) and Cross Laminated Timber (CLT). The main advantage of this amendment is to provide a simple and economical way to join timber parts on segments. This study evaluated by means of tensile tests the capacity of this type of joint (structural dimension of 21mm) to bond together Lyptus ® wood beams (a Eucalyptus grandis and Eucalyptus urophyla hybrid) using Jowat polyurethane glue (Model 680.20) as compared to similar seamless beams. The results indicate that the seamless beams are 47.72% more resistant to traction (in characteristic values) than those with finger joints. However, to form structural elements where there is redundancy overlapping parts, such as Glulam and CLT, the values obtained can be considered satisfactory. Also noted is that denser samples have better traction results due to better bonding of the densest parts. The use of finger-joint and polyurethane adhesive o bond hybrid eucalyptus, although more brittle than wood without seams, enable the use of shorter wood sections for the composition of major structural elements, optimizing better forest material.

Strength of Structural Finger-Joints Reinforced With Fibers

“…Analyzing the results of Table 5, it is possible to verify that all the evaluated treatments, in both species, had presented lesser losses of resistance in relation to the presented one by Raftery & Harte (2013). Pereira et al (2016), in study of unreinforced finger-joints with a hybrid of E. grandis Hill ex. Maiden with E. urophyla S. T. Blake, found out averages of 50.73 MPa for test specimen without finger-joints and 19,10 MPa for test specimens with the finger-joint.…”

Behavior of Metallic and Composite Structures (Second Volume)

“…The simplest grain boundary structure is a straight and non-defective low angle grain boundary: a periodic array of dislocations [53][54][55], as sketched in Figure 1. Notably, the low angle grain boundary may be constructed by two types of dislocation series (each series terminates atomic planes at one side of the boundary) [56,57]. For the high angle grain boundary, the structure may become more complicated.…”

“…Low-quality knots are usually cut, and the obtained elements are combined with the use of finger joints. This technique is known and has been constantly developed since the Second World War [56]. The knots are an important type of defect and due to their dimensions affect in particular the pine wood (Figure 1a,b).…”

The Usefulness of Pine Timber (Pinus sylvestris L.) for the Production of Structural Elements. Part II: Strength Properties of Glued Laminated Timber

“…Low-quality knots are usually cut, and the obtained elements are combined with the use of finger joints. This technique is known and has been constantly developed since the Second World War [ 56 ]. The knots are an important type of defect and due to their dimensions affect in particular the pine wood ( Figure 1 a,b).…”