USAF Summer Research Program - 1995 Summer Faculty Research Program Final Reports, Volume 5A, Wright Laboratory

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the t ring and maintaining the data needed, and completing and reviewing tAe collection" of information. December 1995 PREFACE Reports in this volume are numbered consecutively beginning with number 1. Each report is paginated with the report number followed by consecutive page numbers, e.g., 1-1, 1-2, 1-3; 2-1, 2-2, 2-3.Due to its length, Volume 5 is bound in three parts, 5A, 5B and 5C. Volume 5A contains #1-23, Volume 5B contains reports #24-44 and 5C contains reports #45-64. The Table of ABSTRACTThe basic properties of a newly invented class of hybrid munitions are presented. These Barrel-Launched Adaptive Munitions (BLAM) blend the characteristics of missiles and ammunition to form a new type of guided bullet or cannon shell. The chosen design is a 101 halfangle cone which is split in two with a forward spike and a truncated conical aft skirt. The two pieces are pivoted around a central ball-joint and held together by piezoelectric adaptive tendons. This allows the front portion of the cone to rotate in any direction up to ±10 with respect to the rear portion of the cone.The first part of the study was experimental and involved the fabrication and testing of an active bench-test article and models for range firing. The adaptive tendons were fabricated using newly developed manufacturing techniques which lead to shock-resistant actuators capable of enduring hard launch loads. The prototype tendons were 0.15" (3.81mm) wide and were constructed from a pair of 2.5" (63.5mm) long 7.5 mil (190.5 jm) thick PZT-5H piezoceramic sheets which were sandwiched on either side of 4" (101.6mm) long, 5 mil (127 gm) thick aluminum foil. Test results show that at 68°F (20'C), the adaptive members were precompressed to record levels of 947gstrain (57.8 MPa or 8.37 ksi) while the aluminum substrate was pretensioned to 2473[tstrain (173 MPa or 25.1 ksi). The low substrate-actuator strength ratio (V = 0.381) lead to a 72% maintenance of active strain levels between the free-PZT sheet and combined element performance. Modified laminated plate theory was used to demonstrate that the extremely high pre-compression level was sufficient for withstanding launch loads up to 20,000 g's. At maximum ±400 g.strain levels, the elements could generate articulation angles up to ±0.28'. The BLAM bench prototype was determined to have a first natural frequency of 228 Hz (1,433 rad/s) with a full-cycle response time under 5ms.The second section of research compares the overall performance of conventional ammunition to the projected performance of the BLAMs. Because BLAMs would be insensitive to gravity and most cross-winds (above minimum flight speeds), their effective ranges are substantially increased. A basic performance code compared the 20mm PGU-28 to an identically shaped BLAM. Considering a minimum impact velocity of 700 ft/s (213 m/s), the effective ranges were more than doubled to 2 mi (3.2km). Projections also demonstrated t...