A novel identification method for obtaining bending moment–curvature relations of wood stems based on digital image correlation and SDOF analysis

Abstract

Bending moment–curvature relations (M-χ) are useful in many beam modelling approaches. It allows describing in a simple way the mechanical behaviour at the cross-section scale and can be used to model continuous beams as single degree of freedom systems dedicated to perform stochastic analysis. This paper focused on tree mechanical charaterisation and presents an identification method for obtaining bending moment–curvature relationships up to failure from Digital Image Correlation (DIC) and experimental three points bending tests. Due to wood intrinsic variability, the proposed identification method has been validated from a Finite Element (FE) model which aims at simulating precisely the bending response of a cylindrical stem. The refined FE model has been developed based on the geometry and the boundary conditions of the experimentally tested stems. M-χ curves are derived from the FE model and used within a Single Degree Of Freedom (SDOF) approach. At the stem scale, the prediction of the SDOF model (Force-Displacement) is compared to the FE model and lead to a good agreement. Then the approach is used to characterise fresh European beech samples allowing deriving their mechanical properties (longitudinal Young modulus, modulus of elasticity and modulus of rupture).

Keywords:

• Fresh wood
• digital image correlation
• identification method
• bending behavior
• SDOF model

Acknowledgments

The authors would like to thank the French national project C2ROP (Chutes de blocs, Risques Rocheux et Ouvrages de Protection - Rockfalls, Protection devices and rockfall Hazard) and its scientific community to fruitful exchanges on the subject.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work has been partially supported by RNVOR (Research network on vulnerability of structures undergoing natural or technological hazards).