Direct Transient Analysis of a Fuze Assembly by Axisymmetric Solid Elements

A fuze assembly, which consists of three major parts, nose, collar and sleeve, was designed to survive severe transverse impact giving a maximum base acceleration of 20.000 G. It is shown that hoop failure occurred in the collar after the impact. They also showed that by bonding the collar to the nose, the collar was able to survive the same impact. To find out the effectiveness of the bonding quantitatively, axisymmetric solid elements TRAPAX and TRIAAX were used in modelling the fuze and direct transient analysis was performed. The dynamic stresses in selected elements on the bonded and unbonded collars were compared. The peak hoop stresses in the unbonded collar were found to be up to three times higher than those in the bonded collar. The NASTRAN results explained the observed hoop failure in the unbonded collar. In addition, static and eigenvalue runs were performed as checks on the models prior to the transient runs. The use of the MPCAX cards and the existence and contributors of the calculated first several nearly identical natural frequencies are addressed

Optimum design of structures of composite materials in response to aerodynamic noise and noise transmission

Elastic wave propagation and attenuation in a model fiber matrix was investigated. Damping characteristics in graphite epoxy composite materials were measured. A sound transmission test facility suitable to incorporate into NASA Ames wind tunnel for measurement of transmission loss due to sound generation in boundary layers was constructed. Measurement of transmission loss of graphite epoxy composite panels was also included

Attenuation of stress waves in single and multi-layered structures

Analytical and experimental studies were made of the attenuation of the stress waves during passage through single and multilayer structures. The investigation included studies on elastic and plastic stress wave propagation in the composites and those on shock mitigating material characteristics such as dynamic stress-strain relations and energy absorbing properties. The results of the studies are applied to methods for reducing the stresses imposed on a spacecraft during planetary or ocean landings

Transient analysis using conical shell elements

The use of the NASTRAN conical shell element in static, eigenvalue, and direct transient analyses is demonstrated. The results of a NASTRAN static solution of an externally pressurized ring-stiffened cylinder agree well with a theoretical discontinuity analysis. Good agreement is also obtained between the NASTRAN direct transient response of a uniform cylinder to a dynamic end load and one-dimensional solutions obtained using a method of characteristics stress wave code and a standing wave solution. Finally, a NASTRAN eigenvalue analysis is performed on a hydroballistic model idealized with conical shell elements

Universal Control of Nuclear Spins Via Anisotropic Hyperfine Interactions

We show that nuclear spin subsystems can be completely controlled via microwave irradiation of resolved anisotropic hyperfine interactions with a nearby electron spin. Such indirect addressing of the nuclear spins via coupling to an electron allows us to create nuclear spin gates whose operational time is significantly faster than conventional direct addressing methods. We experimentally demonstrate the feasibility of this method on a solid-state ensemble system consisting of one electron and one nuclear spin.Comment: RevTeX4, 8 pages, 8 figure

Effective range expansion in various scenarios of EFT(\notpi)

Using rigorous solutions, we compare the ERE parameters obtained in three different scenarios of EFT(\notpi) in nonperturbative regime. A scenario with unconventional power counting (like KSW) is shown to be disfavored by the PSA data, while the one with elaborate prescription of renormalization but keeping conventional power counting intact seems more promising.Comment: 6 pages, 3 tables, no figure, revtex4-1, minor revisions, to appear in EP