Improved calculations of joints in anisotropic structural materials

Introduction. Contemporary methods for the design and calculation of building structures are often limited to the elastic stage of the material work. In order to analyze the stress-strain state of joints, it is necessary to take into account the properties of the material, as well as its operation under the load, including both elastic and non-linear stages. In this case, anisotropic materials, e.g. wood, represent a particular interest. Therefore, the paper presents a theoretical and practical study of the work, performed by wooden samples.

Aim. To perform tests and numerical simulations for analyzing the stress-strain state and improve the calculations of anisotropic structural materials.

Materials and methods. Compression tests of wooden samples, made of second-grade pine, were carried out along the fibers with fixed vertical compression stresses and strains. The tests were performed using a hydraulic press with a maximum load of 50 t. Strain gauge equipment was used to record strains and stresses. Based on the data of compression tests, the numerical simulation of the samples in the LIRA-SAPR and ANSYS software packages was performed.

Results. According to the test results, the elastic stage of the compressed wood ranges up to 90 kN, followed by a transition to the plastic deformation. The performed numerical simulation of the samples in the LIRA-SAPR and ANSYS software packages demonstrated the convergence of the results. However, the ANSYS software package allows for a more detailed simulation and calculation of joints and structures. The comparison of distributions of vertical compression stresses σy, obtained in tests and ANSYS software package numerical simulation, proved the convergence of the results (discrepancy of less than 5 %). This confirms the effectiveness of using this software package for simulating the joints of anisotropic materials.

Conclusions. The results of tests and numerical simulation showed the effectiveness of using the ANSYS software package to calculate complex joints of anisotropic structural materials. The convergence of the results is established for the elastic stage. An additional study is required to simulate the plastic stage.

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