PSI - Issue 54

V.P. Matveenko et al. / Procedia Structural Integrity 54 (2024) 218–224 Matveenko V.P., Serovaev G.S., Kosheleva N.A., Galkina E.B../ Structural Integrity Procedia 00 (2023) 000 – 000

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To select the most suitable sample for research, various geometric configurations were considered, as shown in Fig. 1. For all configurations, the boundary conditions assume cantilever fastening on one of the sides and the application of a bending moment using a force directed perpendicular to the plane of the sample, as the most practical and easy to implement. Since the optical fiber with FBGs in the experiment will be attached to the surface of the sample using an adhesive, the strain distribution along the length of the sample on its surface was compared for different designs of the samples. This was achieved by solving the problem of the theory of elasticity in a three-dimensional formulation using the finite element method in the Ansys package. Mechanical properties of PLA plastic E = 3 GPa, ν = 0.35 were used for numerical modeling.

Fig. 1. Sample designs and strain distribution along their lengths.

Based on the obtained results, presented in Fig. 1, it can be concluded that the traditional design of the sample in the form of a cantilever clamped beam with a uniform cross-sectional area is significantly less effective in achieving strain gradient than designs with a linearly and non-linearly varying cross-sectional area along the length of the sample. Specifically, Design 3, characterized by a non-linear variation in cross-sectional area along the length of the sample, enables the realization of a larger strain gradient under the same external force compared to Design 2. Furthermore, by shifting the narrow part of the cross-section away from the clamping site, the influence of this zone on the strain distribution is eliminated. Thus, Design 3, the geometric configuration of which is illustrated in Fig. 2, was selected for further experimental studies.