Physical modeling of fluid-filled fractures using the dynamic photoelasticity technique

We have developed an optical apparatus based on the dynamic photoelasticity technique to visualize and analyze the propagation of the Krauklis wave within an analog fluid-filled fracture. Although dynamic photoelasticity has been used by others to study seismic wave propagation, this study adds a quantitative analysis addressing dispersion properties. We physically modeled a fluid-filled fracture using transparent photoelastic-sensitive polycarbonate and nonsensitive acrylic plates. Then we used a pixel-based framework to analyze the dispersion of a Krauklis wave excited in the fracture. Through this pixel-based framework, we thus demonstrate that the dynamic photoelasticity technique can quantitatively describe seismic wave propagation with a quality similar to experiments using conventional transducers (receivers) while additionally visualizing the seismic stress field. We observe that an increase in the fluid viscosity results in a decrease in the velocity of the Krauklis wave. We also determine the capability of the method to analyze seismic data in the case of complex geometry by modeling a sawtooth fracture. The fracture’s geometry can strongly affect the characteristics of the Krauklis wave as we note a higher Krauklis wave velocity for the sawtooth case, as well as greater perturbation of the stress field.

Stress Wave Truncation Experimental Research Based on Dynamic Photoelasticity

How to truncate stress wave is an important problem that must be considered in design of engineering structure. As an effective detection method of stress distribution, the dynamic photoelasticity has been wide used in stress analysis, such as detection of mechanical structure, civil engineering and water conservancy etc. In this paper, the stress wave isochromatic fringe at different interface structure has been obtained through vertical shooting experiment. The structural stress wave propagation rule of three kinds of case is studied by comparison fringe pattern. The experimental research results show that the stress wave propagation can be effectively guided to a fixed direction through installed connecting parts in structural connection position and the method can avoid integrity damage of structure caused by local large stress changes. Finally, the dynamic photoelasticity is an intuitive and effective way to study stress wave truncation problem.

Investigation of Dynamic Photoelasticity Based on a Three-Dimensional Model

Dynamic photoelasticity has been widely utilized to investigate the phenomena generated by impact loading. The dynamic parameters of structures, such as propagation of stress wave and stress concentration, are obtained through this method, which provide guidelines for structure design and optimization. In the previous studies, two-dimensional models are wildly used by researchers. In these models, the inaccuracy of the boundary conditions leads to error amplification during the conversion of the tested results into real ones. In this study of dynamic photoelasticity, three-dimensional models are used. An improved digital dynamic photoelastic system is also adopted to calculate elastic wave propagation in the medium, where the diode-pumped solid-state green laser and high-speed CCD are used as light source luminaries and recording system respectively. Based on these models, where the boundary conditions approach to true value, the resulting data are higher in resolution than is possible with other experimental techniques. This method has been adopted and tested successfully by generating better results with less amplification of errors.