Grant: Discovery Grants Program - Individual

An adhesive bond represents the most common joining technique in modern engineered wood products (EWPs). Adhesive-laminated Lumber-based mass timber products (ALMTP), such as glue-laminated timber (GLT) and cross-laminated timber (CLT), have been widely used in construction. In these ALMTP, the mechanical performance of a bond-line(s) plays a critical role in the structural behaviour, and furthermore determines the safety and durability of a timber structure. The prediction of the fracture behaviour of GLT and CLT is difficult in both experimental studies and industry practices. Changes in temperature and load during the service life of an EWP could initiate and propagate a crack(s) along a bondline and within wood, causing material discontinuities and furthermore fracture. This proposed program will adopt the peridynamics (PD) to simulate the fracture behaviour of a bondline of ALMTP, which will be coupled with the finite element analysis (FEA) and fracture mechanics (FM), supported by the digital image correlation (DIC) technique. PD is a groundbreaking mathematical framework in the field of continuum mechanics, operating without stress and strain at the mesoscale. It defines the interactions between material points in a solid, considering the influence of neighboring particles within a certain distance, regardless of their spatial arrangement. Thus, PD is a more feasible way of modelling crack initiation and propagation. This research will be the first effort of using PD in wood science and engineering. The overall objective of this proposed program is a study of bond strength of ALMTP in wood buildings by examining their fracture behaviour, thereby contributing to a fundamental understanding of bonding characteristics and overall structural integrity. The specific objectives of this proposed program are to develop a PD-based model and testing method(s) for the evaluation of bond quality of ALMTP. Four graduate students and four undergraduate students will be recruited to apply PD and FM theories and FEA and DIC techniques to conduct crack analyses along the bondlines of ALMTP at room and elevated temperatures. Considerations will be given to lamination direction, adhesive type, and short-term creep at high temperature. The expected outcomes will be: (1) a reliable method(s) for evaluating the bond quality of ALMTP, and (2) a mechanics-based model for describing the fracture behaviour of ALMTP. The expected significance of this program is: (1) a fundamental understanding of the bond characteristics of ALMTP, (2) a proposal on test methods for measuring bond strength of ALMTP to the standard associations like CSA and ASTM, (3) a set of elastic parameters of bondlines made by various adhesives, (4) an understanding of short-term creep of ALMTP at elevated temperature, and (5) training of eight HQP for Canadian wood and construction industries.