Investigation the peculiarities of deformation and strength of timber using laser interferometry method

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Problem statement. Correct assessment of load carrying capacity of connections is crucial for ensuring the structure reliability. The initial parameter for the calculation of load carrying capacity of the timber structures connections is the characteristic embedment strength (the strength of timber massive under dowel penetration). This characteristic can be determined using empiric formulas or through standard experimental investigation. Currently a wide database on the results of the experimental assessment of stress-strain state of timber structures connections exists, which covers the questions of determination of failure patterns, failure load, strength, “load-deformation” dependences etc. Nevertheless, a combination of the standard investigation methods with non-standard techniques allows obtaining more detailed information about the interaction between elements of the connection. The registration of the displacement fields of the surface or volume of the element is possible using optical physics methods, e.g. laser holographic interferometry. The purpose of the article is to investigate the strength and peculiarities of the deformation of timber under the influence of metal dowel using laser holographic interferometry method. Conclusion. As a result of experimental investigations, load-displacement curves, failure loads and maximum displacements were obtained for the samples tested. At each loading stage, interferograms were recorded and three-dimensional graphs of the deformed surface of the sample were obtained, which clearly represent the nature and evolution of the interaction between dowel and timber. The resulting complex of data on the deformation and strength characteristics in further studies will be used to develop and verify the design model of the dowel connection of timber elements taking into account nonlinear work.