Issue 49

N. S. Popova et alii, Frattura ed Integrità Strutturale, 49 (2019) 267-271; DOI: 10.3221/IGF-ESIS.49.26 270 V ALIDATION OF THE VARIATIONAL PRINCIPLE o validate the variational principle for a search of the crack path, the truncated wedge (having 3 mm thickness) (Fig. 3) is tested under concentrated tensile force P at room temperature. The angle between the truncated wedge axis and the lateral surface is 20 o . The specimen is made from the organic glass. Mechanical properties of the material are the following: Young’s modulus E = 3000 MPa, ultimate strength σ u =70 MPa and Poisson’s ratio ν = 0.36. Figure 3 : The scheme of the truncated wedge which is tested under concentrated tensile force. To initiate the crack propagation under concentrated tensile force, the initial notch perpendicular to the lateral surface of the truncated wedge was created. The notch length is 5 mm. The specimen was painted for better visualization of the crack propagation. It can be seen that the predicted crack path is in agreement with the experimental crack path (Fig. 4). Moreover, the crack propagates perpendicular to free surface of the truncated wedge. This result confirms correctness of the employed model and the variational principle to predict the crack path in the wedge under concentrated tensile load. Figure 4 : Comparison of the experimental crack path (a) with the predicted crack path (b) in the truncated wedge under concentrated tensile load. T