Resistance-foil strain-gage technology as applied to composite materials
A general review of existing strain-gage technologies as applied to orthotropic-composite materials is given. The specific topics addressed are gage-bonding procedures, transverse-sensitivity effects, errors due to gage misalignment, and temperature-compensation methods. The discussion is supplemented by numerical examples where appropriate. It is shown that the orthotropic behavior of composites can result in experimental error which would not be expected based on practical experience with isotropic materials. In certain cases, the transverse sensitivity of strain gages and/or slight gage misalignment can result in strain-measurement errors exceeding 50 percent.
Iterative preliminary design tools for composite structures
Abstract Advanced composite materials offer tremendous potential for the optimization of aerospace structures from weight, cost, strength and stiffness perspectives. However, this potential cannot be realized without the aid of advanced composite design tools that have been specifically developed to exploit the unique properties of these materials. This paper presents the philosophy behind a system of semi-empirical composite design programs that have primarily been developed for the preliminary design environment. The structure of the system is described and problems encountered during the development of the system are discussed. Practical examples are used to illustrate the system capabilities.
Study of Lubricant Jet Flow Phenomena in Spur Gears
Lubricant jet flow impingement and penetration depth into a gear tooth space were measured at 4920 and 2560 rpm using a 8.89 cm (3.5 inch) pitch diameter 8 pitch spur gear at oil pressures from 70,000 to 410,000 n/sqm (10 psi to 60 psi). A high speed motion picture camera was used with xenon and high speed stroboscopic lights to slow down and stop the motion of the oil jet. An analytical model was developed for the vectorial impingement dept and for the impingement depth with tooth space windage effects included. The windage effects for oil drop size greater than .0076 cm (.003 inches). The analytical impingement dept compared favorably with experimental results above an oil jet pressure of 70,000 n/sqm (10psi). There was further penetration into the tooth space after impingement, but much of this oil was thrown out of the tooth space without further contacting the gear teeth.