Novel approaches for shear testing of wooden dowels parallel to the grain: an experimental and numerical study

Artikel i vetenskaplig tidskrift, 2026

Wooden dowels transfer load in timber connections through combined mechanisms, including longitudinal shear, bending and embedment. Shear properties parallel to the grain are essential for mechanics-based stiffness models and numerical simulations of wooden dowel connections, yet no standardised method exists for their determination. This study addresses this gap by investigating and optimising shear-testing methods for wooden dowels using experimental and numerical approaches. This study compares four shear-testing approaches for determining the shear strength of wooden dowels using a compression test setup, supported by experimental work, numerical modelling and fundamental mechanics. Parametric FEA in LS-DYNA was conducted to optimise specimen geometry, and the effects of notch-end shape, notch width, failure-plane height and specimen length on stress distribution and failure mode were assessed. Among the four methods, the 45° double-notched specimen was identified as the most effective for generating an approximately pure shear state. Digital Image Correlation (DIC) was used to evaluate five strain-gauge areas and five strain-calculation methods. The validated configuration was then used for further shear testing. The study shows that all optimised specimen configurations produce comparable shear strengths parallel to the grain, indicating the potential suitability of these methods for wooden-dowel shear testing. However, notch shape, notch width, failure-plane height and specimen length must be properly optimised to ensure shear-dominated failure. Smaller virtual strain-gauge areas, particularly the thin-line area method between notch tips, provide more representative shear-strain measurements and shear-modulus values. Numerical modelling using MAT-143 successfully captured the post-peak softening behaviour and supports its use for shear simulations.