. The Bell System technical journal . 2 3 4 5 TIME IN MILLISECONDS Fig. 6—Oscillograph tracings of forces generated in make and break opera-tions. direction of the electrodes. In this process, the crystal is first poled, afterwhich the poling electrodes are ground or etched off and electrodes per-pendicular to the poling direction are put on by using a polimerizingcement in which silver dust is mixed. The cement serves not only as anelectrode but also holds the ceramic in the desired place. Fig. 7 showsan arrangement used for studying frictional forces. A small ceramic )y cm in cross-s
. The Bell System technical journal . 2 3 4 5 TIME IN MILLISECONDS Fig. 6—Oscillograph tracings of forces generated in make and break opera-tions. direction of the electrodes. In this process, the crystal is first poled, afterwhich the poling electrodes are ground or etched off and electrodes per-pendicular to the poling direction are put on by using a polimerizingcement in which silver dust is mixed. The cement serves not only as anelectrode but also holds the ceramic in the desired place. Fig. 7 showsan arrangement used for studying frictional forces. A small ceramic )y cm in cross-sectional area is glued to a metal base while a thinspecimen of the material whose frictional forces are to be studied isglued to the top surface. The forces cavised by a wire drawn over thesurface are transmitted to the crystal and generate a voltage which ap-pears on the oscillograph. Pictures of such force generated voltages are. TANGENTIAL--BARIUM TITANATECERAMIC -SAMPLE Fig. 7—Experimental arrangement for studjing frictional forces. 480 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1952 shown by Fig. 9 of the next section and are discussed there. The sensitiv-ity of this type of unit is higher than that for the normal force measuringunit. As shown in the appendix, the voltage generated is independent ofthe area of application and is about volts for a unit the same size asdiscussed above which gave volts for 100 grams applied at a placing weights on the upper surfaces both types of units can beused as accelerameters. They are cemented to the surface whose ac-celeration is to be measured and the force applied is equal to half themass of the ceramic plus the added mass times the acceleration. By put-ting weights on the shear pickup ceramic types, tangential accelerationscan be measured in the direction of the poling. By using three suchaccelerameters, the normal and two tangential components of acce
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