Modelling of Elevated Temperature Performance of Adhesives Used in Cross Laminated Timber: An Application of ANSYS Mechanical 2020 R1 Structural Analysis Software

Abstract

There is difficulty in accurately modelling adhesive influence in structural performance of cross laminated timber (CLT), due to a lack of available knowledge on the heat performance of adhesives. Therefore, the main aim of this research was to evaluate the thermal and mechanical properties of adhesives used in production of engineered wood products like CLT. The properties of the timber species and the adhesive types used in the simulation were derived from published literature and handbooks. ANSYS mechanical 2020 R1 was employed because it has a provision for inserting the thermal condition and the temperature of the system set to the required one for analysis. The simulations were conducted for temperatures 20, 100, 140, 180, 220, and 260 °C, within which Zelinka et al. conducted their experiments, which have been the basis for the current study. The main findings were, the adhesive layer had little influence on the thermal properties of CLT composite (solid wood had the same thermal properties as CLT), but had a significant effect on the structural properties of CLT composite, the stresses and strains of the simulated wood species reduced with increase in temperature, the adhesives strengths at room temperature were greater than for solid wood at the same temperature and finally, the stresses and strains of the simulated wood adhesives reduced with increase in temperature. It is also important to note that computations for temperature distribution from the char layer were lower than computed using heat transfer equation, and the simulated values from steady state model. All in all, the objectives of this research were met and more research in thermal structural modelling using ANSYS should be conducted in the future.

Burning Properties of Combined Glued Laminated Timber

“…These adhesives retain their bond strength and structural integrity, even under significant heat exposure[50]. RPF adhesives exhibit robust resistance to softening, melting, or delamination when subjected to high temperatures, rendering them suitable for applications where fire resistance and heat stability are critical[51]. In a comparative study by Hartig and Haller (2023)[52] involving gluing spruce, beech, and poplar wood using PUR and phenol formaldehyde glue, poplar wood, closely aligned in density to alder wood, exhibited a similar burning pattern to alder wood, with the second peak reaching heat release rate (HRR) values akin to the first peak.Delamination within the bonded joint poses a significant challenge, particularly in the scenario of heat flux directed from top to surface (orientation 1).…”