Engineering topics

Boatwright, D. W.

Publications and source records attributed to Boatwright, D. W..

3 records

NASA NTRS1993

Elastic plastic fracture mechanics methodology for surface cracks

The Elastic Plastic Fracture Mechanics (EPFM) Methodology has evolved significantly in the last several years. Nevertheless, some of these concepts need to be extended further before the whole methodology can be safely applied to structural parts. Specifically, there is a need to include the effect of constraint in the characterization of material resistance to crack growth and also to extend these methods to the case of 3D defects. As a consequence, this project was started as a 36 month research program with the general objective of developing an EPFM methodology to assess the structural reliability of pressure vessels and other parts of interest to NASA containing defects. This report covers a computer modelling algorithm used to simulate the growth of a semi-elliptical surface crack; the presentation of a finite element investigation that compared the theoretical (HRR) stress field to that produced by elastic and elastic-plastic models; and experimental efforts to characterize three dimensional aspects of fracture present in 'two dimensional', or planar configuration specimens.

Ernst, Hugo A.↗

NASA NTRS1977

Flight test evaluation of a method to determine the level flight performance of a propeller-driven aircraft

A flight test method has been developed for determining the level flight drag and propulsive efficiency of propeller-driven aircraft. The overall drag of the aircraft is expressed in terms of the measured increment of power required to overcome a corresponding known increment of drag, which is generated by a towed drogue. The simplest form of the governing equations, D = delta D SHP/delta SHP (where D is drag and SHP is the horsepower delivered to the propeller) is such that all of the parameters on the right side of the equation can be measured in flight. An evaluation of the governing equations has been performed using data generated by flight test of a Beechcraft T-34B.

Bridges, P. D.↗

NASA NTRS1977

Flight test evaluation of a method to determine the level flight performance of a propeller-driven aircraft

The overall drag of the aircraft is expressed in terms of the measured increment of power required to overcome a corresponding known increment of drag, which is generated by a towed drogue. The simplest form of the governing equations, D = delta D SHP/delta SHP, is such that all of the parameters on the right side of the equation can be measured in flight. An evaluation of the governing equations has been performed using data generated by flight test of a Beechcraft T-34B. The simplicity of this technique and its proven applicability to sailplanes and small aircraft is well known. However, the method fails to account for airframe-propulsion system.

Bridges, P. G.↗