Bio-Based Adhesives for Wooden Boatbuilding

Abstract

The aim of the present investigation was to assess the behaviour of strip-planked parts by comparing wooden specimens glued using two different bio-based adhesives with wooden specimens glued using a conventional epoxy resin generally used in boatbuilding. Experimental tests in accordance with UNI EN standards were performed in order to evaluate mechanical properties such as tensile strength, shear strength, elastic modulus and shear modulus. In addition, compression shear tests were performed in order to assess the shear modulus of the adhesives. The obtained results demonstrate that the mechanical properties of the investigated bio-based adhesives are comparable to, and sometimes better than, the conventional epoxy resin. Moreover, the experimental results give useful information for the design of wooden boats when the strip-planking process is used. Furthermore, a new procedure to assess the shear modulus of elasticity and shear strength, using the application of compression loadings, was proposed. The results were compared to standard lap-joint tests and showed even lower dispersion. Consequently, the testing procedure proposed by the authors is valid to assess shear properties under compression loading, and it can be applied in most laboratories since it involves the use of common testing devices.

On the Structural Response of Bio-Based Adhesives for Wooden Hulls

“…The definition of constraints and applied loads aimed at adequately mimicking the mechanical test carried out in laboratory, that is the tensile strength on scarf-jointed specimens [8]. As regards constraints, a fixed support was placed on the left face of the model, in order to simulate the tightening of the testing machine grip on the specimen.…”

“…As regards the application of bio-based adhesives in wooden boatbuilding technologies, the authors carried out an extensive campaign of mechanical experimental tests presented in [8]. With specific reference to scarf-jointed strips commonly adopted in stripplanking, tensile tests in accordance with the UNI EN 408:2004 Standard "Structural timber and glued laminated timber -Determination of some physical and mechanical properties" [26] were performed on wooden specimens (Figure 7).…”

“…Table 6. Results coming from the mechanical experimental tests for the modulus of elasticity in tension E t,0 in terms of mean value x ̅, RMS value and characteristic value x k (5-percentile) [8].…”

“…In this framework, the introduction of bio-based materials specifically formulated for their use within boatbuilding technologies represents a promising solution to investigate. In particular, bio-based polymers (i.e., polymers with a high content of natural origin, derived from natural and renewable resources such as corn, sugarcane, and natural oils [5,6]) can be employed as both stratification and adhesive resins coupled with other natural materials [7,8]. Focusing on wood as a boatbuilding material, its great properties including remarkable long-term performance characteristics and aesthetically pleasantness [9] are the reasons why it is still considered as a favourite material for a few specialised shipyards.…”

“…Indeed, such products are now commercially available, but their use in boatbuilding has been quite limited so far, causing a significant lack as regards information and data coming from relevant applications. Herein, starting from the results of mechanical experimental tests on wooden joints performed and presented by the authors in [8] and in accordance with the relevant literature [18][19][20], a FEM-based methodology aimed at reproducing the testing procedures by exploiting the data present in both technical datasheets and literature for the selected materials was developed. In particular, the attention was given to the linearelastic behaviour of the tested joints.…”