Full-field deformation characteristics of anisotropic marble under compression revealed by 3D digital image correlation

This work aims to reveal the anisotropic full-field displacemnet and the progressive failure behaviors of interbedded marble under uniaxial compression using three dimensional digital image correlation (3D DIC) technique. The effects of the interbed orientation on the field displacement and strain pattern and the crack evolution were analyzed qualitatively and quantitatively. Testing results show that different stress strain responses can be generated depending on the interbed orientation, and the interbeds influence the localized deformation and high strain concentration pattern. The field displacement evolution curves present different pattern and are impacted by the localized deformation. In addition, the strain localization takes places progressively and develops at a lower rate for rock with 0° and 90° interbed than those of 30° and 60° interbed rock. The quick shear-sliding along the interbed leads to the minimum strength of rock having 30° interbed orientation. It is suggested that rock anisotropic field deformation is structure depended.

Full-Field Displacement Measurements of Helicopter Rotor Blades Using Stereophotogrammetry

This study presents a stereophotogrammetry approach to achieve full-field displacement measurements of helicopter rotor blades. The method is demonstrated in the wind tunnel test of a 2 m diameter rotor, conducted at the 5.5 m × 4 m Aeroacoustic Wind Tunnel of China Aerodynamics Research and Development Center (CARDC). By arranging the retroreflective targets on the special hat installed directly above the rotor hub, the dynamic motion of the rotor shaft was tracked accurately, and a unified coordinate system was established on the rotor. Therefore, three-dimensional coordinates of instantaneously measured targets attached on the blade could be transformed to the unified rotor coordinate system, thereby providing a basis for consistently calculating the blade displacements at different test conditions. Moreover, location deviations of the blade caused by the vibration of the measuring system or the rotor due to freestream and rotor rotation were also effectively corrected through coordinate transformation. Comparisons of experimental and simulation results for a range of hover and forward flight conditions show good magnitude and trend agreements.

Influence of curvature change on soil arching effect in underground space development

This paper mainly studies the behavior of axisymmetric radial interaction between soil and structure under radial stress. Considering the possible factors in the interaction, such as the soil arching effect caused by the finite curvature, a simplified model is established. The influence of curvature change on the stress field, strain field, displacement field and stress-strain relationship is analyzed. Finally, the status of various factors in the axisymmetric radial interaction and the influence of their changes on the interaction are proposed.

Influence of constitutive model on soil structure interface interaction under axisymmetric condition

This paper mainly studies the performance of axisymmetric radial interaction between soil and structure under radial stress. One of the key points is the research on the mechanical properties of the interface. The latter is now the frontier field, and also the focus of this paper's theoretical analysis. Based on FEM, a large-scale international finite element software, this paper attempts to establish a general comprehensive model with comparative function through the advantages of numerical simulation. After obtaining the results, the analysis focuses on the influence of different materials on the interaction, and summarizes the stress field, strain field, displacement field and stress-strain relationship of the model under different materials.