A new diagnostic device for in-situ determination of conventional strength and modulus of deformability in compression of wood parallel to fiber

0433992 - ÚTAM 2015 RIV MX eng O - Others
Kloiber, Michal - Kunecký, Jiří - Tippner, J. - Sebera, V.
A new diagnostic device for in-situ determination of conventional strength and modulus of deformability in compression of wood parallel to fiber.
Conference Proceedings of 9th International Conference on Structural Analysis of Historical Constructions. Mexico City: Instituto de Ingeniería UNAM, 2014 - (Peña, F.; Chávez, M.). ISBN N
R&D Projects: GA MK(CZ) DF11P01OVV001; GA MŠMT(CZ) LO1219
Keywords : semi-destructive device * in-situ measurement * finite element analysis * compression
Subject RIV: JN - Civil Engineering

The article presents a conception and prototype of a new diagnostic tool for in-situ evaluation of wood inbuilt into constructions. Current techniques and tools for structural assessment miss the solution that enables measuring of mechanical properties of wood with help of semi-destructive approach that focuses on longitudinal wood properties in a pre-drilled hole. The proposed device uses the principle of pushing jaws (“mini compression test”) apart from each other in drilled hole of 12mm diameter to get as close as possible to pure compression loading mode in a laboratory. The measurement can be carried out in arbitrary depth in a wooden beam. The output from the device is the conventional strength and the modulus of deformability in compression (MODL) parallel to fiber direction. The principle implemented in the new device was tested both ways the experimental and numerical based finite element analysis. Numerical analyses based on probabilistic approach were performed in ANSYS computational software. Results show an influence of material elastic properties on output measured force that is being measured by the proposed device. The longitudinal modulus of elasticity has the strongest impact on the output force (correl. coeff. 0.96); the radial and tangential moduli and also shear moduli have negligible influence (coeff. lower then 0.1). Experimental determination of the same correlations was done for both loaded and not loaded beam that had real-size dimensions (cross-section was 200x240 mm). Correlations between in-situ and laboratory tests were also generally strong (0.8-0.92), so we can claim the measurement with use of the new device predict the material property very well. Lastly, the preliminary study of the compression in a drilled hole was studied with use of digital image correlation (DIC). This returned information about the imprint of the jaws into the wood and strain distribution around the hole.
Permanent Link: http://hdl.handle.net/11104/0238193