Air Force sbir 04. 1 Proposal Submission Instructions

1. R.H. Walden, “Analog-to-digital converter survey and analysis,” IEEE Journal on Selected Areasin Communications, vol. 17, no. 4, pp. 539-550, April 1999.

KEYWORDS: Multiple Beams, Phased Arrays, Analog to Digital (A/D) Converters, EHF, Sub-Arrays, Digital Signal Processing.

AF04-241 TITLE: Verification of Coldworking and Interference Levels at Fastener Holes
TECHNOLOGY AREAS: Materials/Processes
OBJECTIVE: Develop a technique for determining the residual stresses at coldworked fastener holes and at interference fit fasteners.
DESCRIPTION: The residual stresses that result from coldworking a hole, or using an interference-fit fastener, can significantly increase the life of a structure subjected to fatigue loading. Manufacturing tolerances cause variability in the effectiveness of coldworking holes and interference fit fasteners. Furthermore, there are no inspection techniques to ensure that every fastener hole has been properly worked. Hence, the beneficial effects of coldworking holes and interference fit fasteners are not accounted for in the structural integrity analyses used to determine when to inspect aircraft structure for cracks. A technique for measuring the residual stress around a coldworked hole or interference fit fastener, and ensuring that the beneficial stresses are there, would allow the benefits of coldworking to be accounted for when establishing inspection intervals for critical locations. These time between inspections could be increased resulting in less aircraft downtime. Accurate measurement of residual stresses is difficult in a textured materials such as wrought aluminum with current methods such as x-ray diffraction. Current techniques are not readily deployed to the field. And the time required to make a measurement is not compatible with a maintenance operation.
PHASE I: Demonstrate that the proposed technique can differentiate between holes in aluminum and titanium plate that have been cold expanded different amounts. Establish the accuracy and resolution of the technique. Show that the proposed technique is suitable for use on and around aircraft in a maintenance environment in terms of safety, measurement time and system portability.
PHASE II: Develop prototype system for use on and around aircraft. Establish the accuracy and resolution of the prototype system in the relevant environment. Explore the capability of the prototype system to measure residual stresses from other sources such as fit-up or shot peening.
DUAL USE COMMERCIALIZATION: Residual stresses are found in many different types of structures. Residual stresses can be beneficial or deleterious. A field deployable method for determining the magnitude of residual stresses would be useful for chemical plants and pipelines, ship building, ground vehicles, as well as aviation.
REFERENCES: 1. Split Sleeve Cold Expansion, Fatigue Technology Inc., http://www.fatiguetech.com.
2. Residual Stress Division, Society of Experimental Mechanics, http://www.sem.org/td_517.htm.
KEYWORDS: Residual Stresses, Coldworked Holes, Interference Fit Fasteners, Welding, Structural Integrity, Fatigue, Fracture

AF04-242 TITLE: Comprehensive Structural Health Monitoring (SHM) System

3. Suter, B. W., Multirate and Wavelet Signal Processing, Academic Press, San Diego, CA, 1998.

Non-Stationary, Non-Guassian, Time History

AF04-243 TITLE: System Engineering -- Thermal/Power- Efficiency Assessments of Air Vehicles
TECHNOLOGY AREAS: Information Systems
OBJECTIVE: Develop system engineering relationships and models for performing thermal/power-efficiency assessment of emerging advanced air vehicle designs.
DESCRIPTION: Effective and timely assessments of total thermal and power energy management is critical to the design and eventual cost-effective deployment of emerging air vehicles. Vehicles designed without appropriately taking these issues into account results in vehicles with sub-optimal performance, cost and weight. Existing analytical tools do not incorporate the capability to complete system-level analysis and vehicle level impacts. They cannot support timely system level optimization requisite for roll up from the subsystem to the vehicle level. Expanding current theories, integration framework, modeling techniques and possibly fundamental methodologies including energy-based integration, thermo-economics or exergy analysis may be required for realization of these goals for advanced air vehicle trends. Some of these emerging trends are on-vehicle directed-energy weapons, extremely slow long-loiter-time vehicles that burn fuel at extremely low rates, onboard energy storage systems that transform energy into different forms for temporary storage, extremely small vehicles, and vehicles with no onboard liquids other than fuel. The technique and models should be such that they can be used to model normal behavior of these subsystems and also failed conditions or other abnormalities in which nonlinear and/or second-order effects come into play. Additionally, the subsystem-to-vehicle relationship models must be easily changed as the need arises by personnel who are not experts in computer codes.
PHASE I: The R&D effort in this phase is to identify and evaluate the required expansion of current theories, integration framework, modeling techniques and fundamental methodologies for identify and evaluate emerging air vehicle trends and to develop a limited set of parametric or other relationships that relate subsystem characteristics to vehicle level metrics. Secondly, identify and provide rationale for the most appropriate modeling techniques that can handle both nominal and failure-induced degraded performance for timely trade studies and assessments. The feasibility of these techniques will be demonstrated by the integration of these techniques into existing analysis programs.

PHASE II: In this phase, a prototype trade study and assessment capability for air vehicles will be developed and demonstrated.

1. Hodges, Ernest and Gickstein, Marvin, “Thermal System Analysis Tools (TSAT),” AFRL-PR-WP_TR-2002-2013, 1 January 2002, ADA404721.

2· Gambill, J.M., D.E. Claeys, H.M. Matulich, D.S., and Weiss, C.F., “Integrated Aircraft Thermal Management and Power Generation,” SAE paper # 932055, 23rd International Conference on Environmental Systems, Colorado, Springs, CO, 12-15 July 1993.

3· Bejan, Adrian, “A Role for Exergy Analysis and optimization in Aircraft Energy-System Design,” ASME International Mechanical Engineering Congress, Nashville, TN, 14-19 November 1999.

AF04-244 TITLE: Flow Control for Enhanced Sensor Beam/Directed-Energy (DE) Beam Quality

Recent advances in the application of active flow control to shear layers offers hope that a solution to shear layer wave-front distortion can be found. It is expected that offerors will be familiar with both low frequency and high frequency types of flow control actuators, and will be prepared to investigate the effects of both types. Simulation and modeling efforts are also encouraged (for questions of scaling), with the caveat being that high-frequency forcing is currently out of reach for most practical computational fluid dynamics (CFD) techniques. The technical areas to consider, but not limited to, shall include the following: principles of active flow control for management of beam degradation, development of improved methods of measuring and predicting beam degradation both in simulated wind tunnel tests as well as in flight, development of practical shear layer aero-optical degradation solutions, designs to improved tests for measuring beam degradation in optical turret/apertures integrated aboard modern aircraft, and development of simulation and modeling/CFD prediction tools for enhanced laser beam propagation.

AF04-245 TITLE: Exergy–Based Design and Analysis for Optimization of Aerospace Components and Systems

DESCRIPTION: Deployment of future aerospace systems will require an intensive system–level integration of components to meet the urgent need at all system levels to minimize the risk and costs. The growing complexity of aerospace systems and the resulting increase in susceptibility to failure due to improperly design–integrated components, dictate a critical need for improved analysis and optimization methods for predicting, evaluating, and optimizing performance [1]. Traditionally, air vehicle analysis and design has relied almost exclusively on extensive trade studies and very costly prototype development of complete aircraft systems that provide only limited insight. The numerous combinations of test parameters required for an overall system–level analysis make complete testing of complex configurations prohibitively expensive if not impossible due to lack of ground–testing facilities capable of replicating critical trajectory regimes. A new approach based on extending the second–law of thermodynamics for complex systems–level analysis has emerged [2]. A computer–based system level simulation and analysis capability based on the concept of work–potential loss (exergy) could conceivably minimize ground–based testing and substantially reduce certification time and costs, as has been proposed for integrating turbine engine analysis and design [2]. While component level computational analysis techniques are well developed and understood, the same is not true for system level analysis where multiple physical phenomena are present and contribute to work–potential losses. Research is needed to bridge the gap between component level and system (e.g., aircraft) level aero–thermodynamic phenomena to more clearly ascertain the applicability and feasibility of an exergy–based approach. Knowledge gained from this research can then be applied toward the development of high–fidelity system-level analysis techniques that can be used to streamline the analysis, design, and optimization process.