The frequency characteristics and statistical properties of the buffet loads measured on the unswept wing and tail of a fighter airplane have been studied in the stall and in the shock regime. The results indicate that the wing loads in buffeting can be treated as the Gaussian response of a simple elastic system. The tail loads appear to represent a more complicated pattern.

An investigation has been made to determine the effect of wing fences, a wing leading-edge extension, changing wing sweepback angle from 40 to 45 and 50 degrees, fuselage contouring, and varying horizontal tail height upon the buffeting response of some typical airplane configurations employing sweptback wings with high aspect ratios. The tests were conducted through an angle-of-attack range at Mach numbers varying from 0.60 to 0.92 at a Reynolds number of 2 million.

Includes the Committee's Technical reports no. 1-1058, reprinted in v. 1-37.

The vast majority of vibrations encountered in the real environment are random in nature. Such vibrations are intrinsically complicated and this volume describes the process that enables us to simplify the required analysis, along with the analysis of the signal in the frequency domain. The power spectrum density is also defined, together with the requisite precautions to be taken in its calculations as well as the processes (windowing, overlapping) necessary to obtain improved results. An additional complementary method – the analysis of statistical properties of the time signal – is also described. This enables the distribution law of the maxima of a random Gaussian signal to be determined and simplifies the calculation of fatigue damage by avoiding direct peak counting.

About the Series: This important new series of five volumes has been written with both the professional engineers and the academic in mind. Christian Lalanne explores every aspect of vibration and shock, two fundamental and crucially important areas of mechanical engineering, from both the theoretical and practical standpoints. As all products need to be designed to withstand the environmental conditions to which they are likely to be subjected, prototypes must be verified by calculation and laboratory tests, the latter according to specifications from national or international standards. The concept of tailoring the product to its environment has gradually developed whereby, from the very start of a design project, through the to the standards specifications and testing procedures on the prototype, the real environment in which the product being tested will be functioning is taken into account. The five volumes of Mechanical Shock and Vibration cover all the issues that need to be addressed in this area of mechanical engineering. The theoretical analyses are placed in the context of the real world and of laboratory tests - essential for the development of specifications. Volume III: Random Vibration The vast majority of vibrations encountered in the real environment are random in nature. Such vibrations are intrinistically complicated, and this volume describes the enabling process for simplification of the analysis required, and the analysis of the signal in the frequency domain. Power spectrum density is also defined, with the requisite precautions to be taken in its calculation described togther with the processes (windowing, overlapping) necessary for improved results. A further complementary method, the analysis of statistical properties of the time signal is described. This enables the distribution law of the maxima of a random Gaussian signal to be determined and simplifies calculation of fatigue damage to be made by the avoidance of the direct counting of peaks.

This volume contains eighteen selected papers presented at the Second International Conference on Stochastic Structural Dynamics, which are related to new practical applications in the field. This and a companion volume, related to new theoretical developments, constitute the proceedings of the conference, and reflect the state of the art of the rapidly developing subject. The conference was held in Boca Raton, Florida during May 9-11, 1990 hosted by the Center for Applied Stochastic Research of Florida Atlantic University. A total of 20 technical sessions were organized, and attended by eighty participants from 12 countries. Special emphases of the conference were placed on two areas: applications to earthquake engineering and stochastic stability of nonlinear systems. Two sessions were dedicated to the memory of late Professor Frank Kozin, one of the founders and most active contributors to the stochastic stability theory. We are indebted to the National Center for Earthquake Engineering Research (NCEER) for financial support. Most credit belongs to each of the authors whose contributions were the very basis for the undoubted success of the conference. We are grateful to the reviewers who carefully refereed the contributions for these two volumes. Our special thanks are due to Mrs. Christine Mikulski, who carried out all the necessary secretarial tasks associated with the conference with dedication.