Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 746.89K | Year: 2014
ABSTRACT: The overall technical objective of this Phase II effort is to develop computational tools for computing response sensitivities of parametric multi-disciplinary air vehicle systems that exhibit nonlinear dynamic behavior for use in gradient-based optimization, smart sampling, uncertainty quantification, and risk assessment. To this end, the ZONA/MIT team will extend the 2-D ZEUS time-domain unsteady adjoint solver developed in Phase I to 3-D adjoint solver. Also, a structural adjoint method formulated in Phase I will be incorporated in ASTROS to establish a 3-D time-domain ZEUS and ASTROS coupled aero-structure adjoint system. Meanwhile, based on the frequency-domain adjoint solver developed in the ZEUS linearized Euler solver, a frequency-domain flutter sensitivity system will be developed. Both the time-domain and frequency-domain systems will be applied to complex configurations to compare their computational efficiency and accuracy. The 3-D time-domain ZEUS and ASTROS coupled aero-structure adjoint system will be used to perform uncertainty quantification and risk assessment of 3-D wings. Finally, the ZONA/MIT team will incorporate the newly developed least squares sensitivity analysis methodology into the ZEUS code. This new capability will be applied to complex systems involving chaotic aeroelastic oscillations such as a 3-D wing with freeplay and 3-D panel flutter under supersonic/transonic flight conditions. BENEFIT: With performance requirements becoming more stringent and with the need for robust, optimum and cost effective, the designs of the next generation military aircraft are most likely to be non-conventional. Numerous parameters are needed for aircraft descriptions of non-conventional. In order for early identification of critical physical behaviors of those design concepts, response sensitivities with respect to those numerous parameters are required. The proposed adjoint solver can avoid proportional cost growth in sensitivity analysis and efficiently enable rich, parametric aircraft models to be optimized. Once developed, the proposed adjoint solver can be integrated into a multi-disciplinary design analysis and optimization systems as an efficient sensitivity generator for gradient-based optimization involving numerous design parameters. Thus, the proposed adjoint solver will be an enabling technology for the long-term goal of automating aircraft design.
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 749.95K | Year: 2013
ABSTRACT: The overall technical objectives of the Phase II efforts are to develop, implement, and validate a computationally efficient and accurate buffet load predictive capability in ZONA's Stick-To-Stress Dynamic Flight Simulation (STS-DFS). This capability will allow a continuous simulation of the aircraft in STS-DFS for smoothly varying angle of attack and speed providing aircraft attitude, structural deformations and stresses, as well as accumulated fatigue damage due to buffet loads in additional to maneuver loads and in the entire range of Mach numbers. To achieve the Phase II technical objectives, CFD generated data will be combined with experimental data to build a compact buffet model that is valid for a wide range of angles of attack and speeds. This compact buffet model will be incorporated in STS-DFS to complement its current wide ranging capabilities to further include buffet loads to the aircraft. To address the fatigue life concerns due to buffet loads, a fatigue module will also be added in STS-DFS which builds upon its current stress predictive capabilities. The time histories of these stresses will be processed through a rainflow cycle counting which will provide increments in fatigue damage estimated using one of several accumulation rules broadly used. BENEFIT: The U.S. Air Force, Navy, and Army will benefit from the STS-DFS capabilities to simulate the key aeroelastic coupling mechanism between structural dynamics and nonlinear unsteady aerodynamics, the store ejection, maneuver, gust, and buffet loads, including the effects of uncertainty associated with aircraft-to-aircraft variability. The buffet loads predictive capability will be particularly useful to identify potential fatigue problems on U.S. advanced fighters such as the F-35 and F-22 because both have twin-vertical-tail designs. These twin vertical tails are immersed in the separated flow during high-angle-of-attack maneuvers and suffer from high buffet loads. Application of the STS-DFS to those fighters will permit the fatigue life estimation of their vertical tail structures. Several U.S. military aircraft such as the F-16, F-15, C-5 and A-10 are reaching or are already beyond their originally designed fatigue life. To identify their residual fatigue life or extent their fatigue life by retrofit, accurate loads spectra to perform ground fatigue test on those aircraft are required. To establish such loads spectra, engineers must perform simulations for various mission scenarios that the aircraft may experience during their life cycle. Such loads spectra can be generated by STS-DFS using its broad simulation capabilities for loads generation.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.81K | Year: 2014
The overall objective of this Phase I project is to develop a hybrid approach in FUN3D, referred herein to as the Linearized FUN3D, for rapid aeroelastic and aeroservoelastic (ASE) design and analysis. The Linearized FUN3D solves a linearized Euler equation with a transpiration boundary condition using the FUN3D steady N-S solution as the steady background flow to efficiently generate a Reduced Order Model (ROM) in the form of the frequency-domain Generalized Aerodynamic Forces (GAF) matrices due to the structural modes, control surface kinematic modes and gust excitation. The Linearized FUN3D can generate an accurate unsteady aerodynamic solution in the small perturbation sense about a nonlinear steady flow condition. It also can avoid the moving mesh problem associated with applying the exact N-S boundary condition which requires additional computational resources, and becomes very complex in dealing with the discontinuous displacement in mode shapes such as the control surface modes for which generating a computational mesh could be a very tedious effort. In order to enable the Linearized FUN3D to perform frequency-domain open-loop and closed-loop aeroelastic analysis and to generate a plant model in terms of state space equations, several modules in ZAERO, ZONA's flagship commercial software for aeroelastic, ASE, and gust analysis, will be incorporated into the Linearized FUN3D. One can directly import such a plant model into MATLAB to design a flutter suppression and Gust Loads Alleviation (GLA) control system using the modern control design schemes available in MATLAB. The accurate flow field prediction of the wing pressures when a spoiler is deployed is currently beyond the capabilities of the existing aeroservoelastic codes. The wind tunnel measured unsteady pressures on the Benchmark Active Controls Technology wing will be selected to validate the proposed Linearized FUN3D for unsteady aerodynamic prediction due to spoiler oscillations.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 749.96K | Year: 2015
In Phase I, a prototypical FUN3D-based ZONA Euler Unsteady Solver (FunZEUS) was developed to generate the Generalized Aerodynamic Forces (GAFs) due to structural modes, control surface kinematic modes, and gust excitation using a frequency-domain linearized unstructured Euler solver based on the Navier-Stokes solution of FUN3D as the steady background flow. These GAFs can lead to a state-space equation representing the plant model for rapid aeroelastic and aeroservoelastic (ASE) design and analysis. The overall technical objective of Phase II is to develop and validate a production-ready FunZEUS that will be developed by enhancing the prototypical FunZEUS (1) to drastically improve its computational efficiency; (2) to expand its commercialization potential by interfacing with other commercial CFD codes; (3) to include the static aeroelastic effects in the GAF generation; (4) to demonstrate its applicability to complex configurations; (5) to showcase its plant model generation capability using spoilers and other control surfaces; and (6) to improve its maintainability and modularity by integrating all modules in a ZONA's database and dynamic memory management system.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2014
The overall technical objective of this multi-phase project is to develop and validate a so-called 'AAW-Process' that consists of (i) the Active Aeroelastic Wing (AAW) technology of employing multiple control surfaces in tandem for achieving loads alleviation and drag minimization using the over-determined trim capability of ZONA Euler Unsteady Solver (ZEUS), and (ii) the aeroelastic tailoring technique for optimum stiffness distribution and weight minimization while satisfying structural design constraints using ZONA's Automated STRuctural Optimization System (ASTROS). The technical objectives specific to Phase II effort are twofold: (1) Analytically design the four Subsonic Ultra Green Aircraft Research (SUGAR) wind-tunnel models that employ Distributed Multiple Control Surfaces (DMCS) and Variable Camber Continuous Trailing Edge Flap (VCCTEF) to achieve the weight and drag benefits, and (2) Fabrication of one of these four designed models to validate the AAW-process experimentally by a future wind tunnel testing. As per the first specific objective, four wind tunnel models will be designed for high speed Transonic Dynamic Tunnel (TDT) testing along with their detailed fabrication and wind tunnel testing plans. These four models are carefully chosen to incrementally demonstrate the benefits of applying AAW technology and aeroelastic tailoring technique by potential future fabrication and wind tunnel tests. As per the second specific objective, the fabricated wind tunnel model will be delivered to NASA along with its target performance improvement predicted by AAW-process for validation with a near-term wind tunnel testing. In order to ensure the safety of the wind tunnel models during the TDT testing, flutter suppression and gust load alleviation controllers will be designed for those models that are not aeroelastically tailored and have analytically displayed potential flutter instability problems.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.93K | Year: 2016
The overall technical objective of the Phase I effort is to develop a nonlinear aeroelastic solver utilizing the FUN3D generated nonlinear aerodynamic Reduced Order Model (ROM). Two types of aerodynamic reduced order models will be developed; the first is the Neural Network nonlinear ROM that can provide the aerodynamic feedback forces due to structural deformation and the second is a nonlinear Volterra-kernels-based gust ROM that provides the aerodynamic forces due to gust excitation. Once developed, this nonlinear aeroelastic solver will be integrated into the Nonlinear Dynamic Flight Simulation (NL-DFS) system in Phase II to perform flight dynamic simulation including nonlinear aeroelastic and nonlinear rigid body interaction effects, which can be used to predict the gust loads, ride quality, flight dynamic stability, and aero-structural control issues. In addition, the nonlinear aeroelastic solver developed can be a standalone code for rapid static/dynamic aeroelastic analysis. With the utilization of the FUN3D generated nonlinear aerodynamic (ROM), this nonlinear aeroelastic solver will be computational efficient for accurate flutter analysis, gust loads analysis and limit cycle oscillation analysis.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 747.12K | Year: 2014
ABSTRACT: The ability to extract structure mode shapes, accurate system frequency/damping and to predict the onset of flutter/LCO in a real-time capacity from flight/wind tunnel test data are some of the toughest challenges facing control room engineers today. In Phase I, ZONA Technology successfully developed prototype IADS ActiveX controls (i.e., the ZAMS+ Toolset) towards meeting these challenges. In Phase II we propose to mature and extend the ZAMS+ Toolset to establish a simple-to-use, user-friendly, commercially-viable software for the entire IADS flight test community. First, a Windows pre-processing program will be developed to provide a fast and parametrical graphical approach to setup the ZAMS+ 3D surface panel models and all required input for mode shape visualization. Second, the system identification capability of ZAMS+ OMS will be extended with a broadened CDSS method and innovative Physical Modes Selection Algorithm to support real-time flutter predictor capability. The new ZAMS+ OMS will provide both a full user-interactive and automated "hands free" approaches towards system identification and flutter prediction. Third, to support Ground Vibration Test (GVT) derived modes, a new data loader will be added for loading and display of GVT derived modes to supplement the current analytical mode capability used for overlaid mode shape correlation. BENEFIT: The proposed research and development effort will enhance flight test control room personnel's capability to obtain: (1) overlaid mode shape correlation of flight test system extracted modes versus analytical or GVT derived modes on 3D surface panel models, (2) the modal participation of the natural modes to the aircraft's aeroelastic response, (3) accurate aeroelastic system frequency and damping to gauge aircraft stability, and (4) flutter/LCO prediction via two flutter prediction approaches. The mode shape correlation display, in conjunction with the aircraft aeroelastic response displayed in the existing ZAMS tool, will help engineers identify how the structure modes interact with the aerodynamics throughout all flight conditions. The commercial potential for ZAMS+ Toolset is great as real-time mode shape identification, accurate system frequency/damping, and flutter prediction capability are crucial data to obtain for all wind tunnel and flight tests. The resulting ZAMS+ toolset will also provide valuable insight into the aero-structure interaction phenomenon that can lead to reduced flight testing. Mode shape correlation can also alleviate costs and burden associated with GVT. Users of these tools will include IADS customers, such as, Edwards AFB, Eglin AFB, Naval Air Weapons Center, Korean Aerospace, Pratt & Whitney, Israeli Air Force, Singapore Air Force, Cessna, Bell Helicopter, Northrop Grumman, Alenia/Italy, General Atomics, Boeing, Gulfstream, Holloman AFB, Raytheon, Hill AFB, and Lockheed.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.94K | Year: 2014
ABSTRACT: Both commercial and military aircraft are being flown/utilized for extended operational time. The aircraft cumulative flight hours often times extends the original design limits. Each different aircraft manufacturer calculates aircraft fatigue and damage using different techniques. A more accurate prediction of remaining life and inspection interval for an individual aircraft is required, as these aging aircraft are kept in operational status. ZONA Technology, Inc. has been working closely with The Boeing Company to develop a software process to more accurately predict the maneuver loads on an aircraft. This program is called"Stick-to-Stress Dynamic Flight Simulation"(StS-DFS) that can generate structural component loads and stresses due to a pilot stick input command. In the Phase I effort, we will further enhance StS-DFS to adopt previously recorded flight data as input and account for the mass variations due to fuel burn and mission-dependent stores to reflect the impact due to variations in pilot, payloads and fuel burn on the loads of the aircraft. The F-15 Saudi aircraft, an on-going Boeing's project for verifying an new"fly-by-wire"capability, will be selected to validate the enhanced StS-DFS with the newly acquired flight test data from the F-15 Saudi flight test. BENEFIT: Recently, the Air Force Research Laboratory has produced a long-term vision, called the Airframe Digital Twin that calls for the development of a physics based process of determining initial or remaining aircraft structural life. The outcome of the proposed Phase I effort will be one of the crucial early steps towards the Airframe Digital Twin vision. Several U.S. military aircraft such as F-16, F-15, C-5 and A-10 and commercial aircraft are reaching or are already beyond their originally designed fatigue lives. To identify their residual fatigue life or extend their fatigue life by retrofit, accurate loads spectra to perform fatigue analysis or ground fatigue tests on these aircraft is required. Such an accurate loads spectra can be generated by StS-DFS using the recorded flight test data of individual fleet members of these aircraft as input to keep track of the individual fatigue life as proposed in the USAF Digital Twin vision with the concept of improved fatigue calculation. In Phase II, the ZONA/Boeing team will develop a process that can extract the stresses generated by StS-DFS around the identified fatigue critical regions in the structure and use these stresses as input to their respective structural component damage tolerance models; leading to an updated life prediction and inspection interval of an individual aircraft.
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 149.91K | Year: 2015
ABSTRACT: Several current fighter aircraft with external store configurations persistently encounter Limit Cycle Oscillation (LCO) problems. A fast and accurate aeroelastic prediction is required to identify the critical LCO configurations given the massive number of aircraft with store combinations short-time frame demanded by rapid military responses when facing todays ever-changing international situation. To meet this requirement, a LCO predictive tool based on the ZONA Euler Unsteady Solver (ZEUS) will be developed in Phase I. It will include a Message Passing Interface (MPI) implementation to drastically reduce the computational time of ZEUS. Since many studies have shown that the nonlinear aerodynamics alone is not sufficient to yield LCO, rather LCO is due to both nonlinear aerodynamics and Nonlinear Structural Damping (NSD), a generalized van der Pol NSD model will be incorporated into ZEUS to provide a LCO bounding mechanism in the post flutter flight conditions. The LCO predictive capability of ZEUS with MPI will be demonstrated through benchmark comparisons with flight test data. Prior to the end of Phase I, a prototypical ZEUS with MPI version will be installed in the users computational environment to ensure the compatibility between the ZEUS MPI and the users computational architecture. BENEFIT: LCO is a self-excited, sustained vibration of limited amplitude which can impact a pilots control authority over an aircraft, ride quality, and weapon aiming capability. It can also induce structural fatigue and, under certain circumstances, flutter. The LCO clearance of a modern fighter aircraft should be addressed for all possible store/weapon configurations. Given the drastic number of such configurations, this effort is a major engineering task in aircraft/store weapon compatibility certification. The outcome of Phase I will be a LCO predictive tool that can meet the requirement of computational efficiency to generate time-history response solutions for numerous flight conditions per day on conventional multi-processor computer platforms so that potentially dangerous configurations can be identified with confidence reducing the need for flight testing.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 749.79K | Year: 2015
ABSTRACT:Both commercial and military aircraft are being flown/utilized for extended operational time; a more accurate prediction of residual life and the inspection interval for an individual aircraft is required, as these aging aircraft are kept in operational status. A technique for converting actual aircraft measured flight usage data into accurate calculated stresses/strains on the structural "hot spots" via physics-based, real-time aeroservoelastic simulations will be extremely useful to the Air Force to continue the operational readiness of its aging fleet. In Phase I, ZONA Technology, Inc. successfully demonstrated distributed loads calculations using the Stick-to-Stress Dynamic Flight Simulation (StS-DFS) framework and F-15 Saudi (F-15SA) flight test data, taking into account changing fuel mass. The overall objective of the Phase II effort is to establish a broad simulation capability for loads generation using StS-DFS, including store mass variation. We will use the F-15SA as a demonstration case to validate StS-DFS predicted loads with flight test data, account for variation of mass and pilot from aircraft to aircraft, generate stress time history due to various maneuvers, and perform fatigue analysis for estimation of residual fatigue life. The outcome of this effort shall be a crucial step towards the Airframe Digital Twin vision, leading to an updated life prediction and inspection interval of individual aircraft.BENEFIT:The technology developed during this Phase II effort will result in a technique for converting actual aircraft measured flight usage data into accurate calculated stresses/strains on the structural hot spots via physics-based, real-time aeroservoelastic simulations; this resultant technology is called the StS-DFS Framework. The StS-DFS Framework will have the capability to simulate the key aeroelastic coupling mechanism between structural dynamics and nonlinear unsteady aerodynamics with classical rigid body dynamics to generate a broad range of loads including the store ejection loads, maneuver loads, gust loads, buffet loads with the consideration of the effect of uncertainty associated with aircraft-to-aircraft variability, leading to an estimation of residual fatigue life of the airframe. This capability is a crucial early step towards the Airframe Digital Twin vision. The StS-DFS Framework will promote physical understanding of observed in-flight dynamic behavior by virtual flight test simulations. Since the StS-DFS Framework is able to accurately predict the fatigue life and damage of individual aircraft, it will be highly desirable to both military and commercial aircraft companies. The target customers for the StS-DFS Framework include all aircraft manufacturers, owners, and maintenance organizations, most of which are current ZONA customers. Potential customers include Edwards AFB, Eglin AFB, AFRL, NASA, NAVAIR/NAWC/Navy, US Army, Lockheed Martin, Boeing, Northrop-Grumman, Raytheon, General Atomics Aeronautical Systems, Cessna Aircraft, Pilatus, Airbus, and others.