Progressive damage analysis of embedment of metal washer into timber

ABSTRACT

Metal washers are widely used in joints of timber structures. Thick washers embed fully into timber, whereas thin washers partially embed into timber due to their bending deformation. For thick washers, physical models have been proposed to estimate the stiffness and strength of timber. However, for thin washers, these estimation methods are insufficient. The objective of this study is to propose a finite-element analysis (FEA)-based approach to predict the stiffness and strength of wood during washer embedding, as well as forecast plasticity and damage behaviours of timber, regardless of the washer size. The FEA used a constitutive model with plastic and damage criteria for timber. In the FEA, an explicit dynamic solution method was used to prevent solution divergence. The FEA reproduced the embedment load–displacement relation and damage behaviours of three species. In addition, the FEA predicted the initial stiffness, second stiffness, and yield load with error margins of 12%, 16%, and 7%, respectively. The influences of the loading speed and mesh fineness on the FEA were investigated numerically to validate the results. In addition, parametric studies on contact stiffness and damage constants were conducted to understand the influences of material constants on the embedment behaviours of FE models.

KEYWORDS:

• Finite-element analysis
• continuum damage mechanics
• contact stiffness
• conifers

Acknowledgement

We thank Mr. Taichi Nishikawa and Hiroki Sugasawa, former undergraduate students at Niigata University, for their assistance in the material tests.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by a grant from the Maeda Engineering Foundation.