Construction of a Dual-Focus High Speed Camera

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A new dual-fucos type, high speed Cranz-Schardin camera has been developed. Using this camera, various photomechanics studies were performed concerning dynamic fracture in polymers and inorganic glasses.Performance of the camera : (a) Dual-focus photography is realized by introducing a beam splitter within a camera box. Two film sheets, placed perpendicularly, can be focused on two kinds of image planes. (b) Framing rate is 1 frame - 1.25 million frames per second. (c) Total number of frames is 30 + 30 = 60. (d)Light sources are 30 spark lights.Using this camera, the following studies were performed :(1) New criterion on the initiation of crack branching.(2) Symultaneous high speed photography by photoelastic and caustic methods, and comparison of K_<ID> obtained through both methods.(3) Analysis of strain gauge data from a dart of instrumented impact testing apparatus.(4) A study of spark light source geometry to improve photographic resolution in shadowgraphy.(5) Dependence of the K_<ID>-A relationship on specimen geometry.(6) Dynamic fracture behavior along an adhered boundary layer.(7) Framing-speed-varied high speed photography of fracture in thermally temperedi.