Photoelastic Study of Wave Propagation in Layered Media
Abstract
This program studies photoelastically the transmitted, reflected and refracted waves resulting when a wave generated by explosive or air-shock loading reaches the plane interface between two birefringent materials of different impedances. Dynamic photo-elastic and photoviscoelastic methods complemented by moire techniques were used. A special explosive loading system using PETN (Pentaerythritol Tetranitrate) was developed. A shock tube was used for air-shock loading. The photoelastic and moire fringe patterns in the explosively loaded models were photographed with a Cranz-Schardin multiple spark camera operating at a rate of 200,000 frames per second. A Fastax camera was used in recording similar patterns in the air-shock loaded models. A class of birefringent model materials with controllable impedance was developed. All models consisted of two layers of birefringent materials having an impedance ratio of 2:1. The models were loaded by a buried explosive source in the low- impedance medium, a buried explosive source in the high-impedance medium. The distance of the point of loading from the interface was varied. Propagation and attenuation characteristics of incident, reflected and refracted waves were studied. The formation of headwaves at the interface was clearly evident in one case. Stress determinations were made in some instances using photoelastic and moire data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1969
- Accession Number
- AD0859194
Entities
People
- I. M. Daniel
Organizations
- IIT Research Institute