A Method for Dynamic Characterization and Response Prediction Using Ground Vibration Test(GVT)Data for Unknown Structures.

The Objective Of This Proposed Work Is To Develop A Reliable Method For Dynamic Characterization And Prediction Of Dynamic Response Of Structures Of Known/Unknown Configurations, By Processing The Free Vibration Data Generated Experimentally From The Ground Vibration Tests (GVT)Of The Prototype Vehicles. The Methodology Would Make Use Of The Measured Dynamic Data In Terms Of Mode Shapes, Natural Frequencies, Modal Damping, Point Impedances Etc.And Generate Modal (Scaled) Stiffness And Inertia Information That Will Be Used For Prediction Of Response Characteristics Of The Prototype Structure . With These Objectives, The Present Work Develops The Mathematical Formulation Of The Method, And Demonstrates Its Reliability By Performing The Experiment On A Simple Cantilever Beam To Determine Its Dynamic Characteristics. Results On Scaled Modal Stiffness And Inertia, Generated Through The Method Using Experimental (GVT) Data Show Excellent Agreement With Those Generated By FE And Analytical Models .It Must Be Noted That A Valid Benchmarking Is Performed With The Condition That The Experimental Procedure Is 'Blind' To The Actual Stiffness And Inertia Distributions As Used In FEM Or Analytical Models . Agreement Of The Predicted Response Of The Structure With That From Direct Experiment And Those From The FE And Analytical Models Indicates That This Method Will Be A Promising Tool To Predict The Dynamic And Aeroelastic Characteristics Of Any Prototype Vehicle In The Future. Once The Reliability Of The Method Is Established,It Can Be Extended To Determine The Dynamic And Aeroelastic Characteristics Of All Aircraft For Which Dynamic Characteristics Are Available From A Ground -; Vibration Test (GVT)

Vibration Control Studies Using an Impedance Method

This paper presents a vibration control methodology that is useful in practical applications where the system to be controlled is difficult to model due to the presence of uncertainties or complex boundary conditions. The impedance control method uses a power flow approach wherein the controller is designed such that power flow into the structure is minimised. This is accomplished by using the dereverberated point impedance function at the actuator location for the design of the controller. The method is implemented and simulated for a cantilever beam with piezoceramic actuators. As a preliminary step towards real-time implementation of impedance control a simple state feedback algorithm is implemented using a dSPACE digital signal processor (DSP) card

Flutter prediction of a swept back plate using experimental model parameters

The model parameters such as eigen values & vectors play a very important role in formulation of unsteady/steady aerodynamics and the subsequent derived aeroelastic results like flutter speeds etc. Slight variations in these values have noticeable changes in flutter characteristics. In the procedure proposed in this paper, the eigen values and mass normalized eigen vectors replace the values obtained through a normal modes solution of the equivalent finite element model of a swept back plate by invoking a Direct Matrix Abstraction Program (DMAP) sequence in the flutter solution of NASTRAN using statements available in DMAP. In case of use of ZAERO software for flutter computations, the eigen values and eigen vectors in the normal modes results file, obtained from NASTRAN is replaced directly with the experimentally obtained values. The flutter solution of the structure continues with the replaced eigen values and vectors. The flutter results obtained by using the FE model of a swept back plate with known geometric and material properties has been compared with the developed program sequence using experimental modal parameters. The studies have been done for both the cases, using unsteady doublet lattice aerodynamics in case of NASTRAN and ZONA6 aerodynamics for ZAERO software. Thus the errors, that result in a finite element normal modes analysis, caused due to improper representation of the boundary conditions, material properties and damping has been eliminated and the program sequence helps in a realistic prediction of flutter characteristics of the structure with the only requirement of the geometric configuration of the structure and need no material property, mass or stiffness related parameters for the finite element modeling of the structure

Ground Resonance Testing of 500 kW Wind Turbine GFRP Blade

Ground Resonance Test is essential to determine the dynamic characteristics, such as Natural Frequencies, Modal Damping, Mode shapes and MAC Matrix. The 500 kW Wind turbine GFRP blade was subjected to GRT in order to find the dynamic characteristics experimentally. The wind turbine GFRP blade was rigidly attached to the static test rig in order to simulate the cantilever boundary condition. SISO test technique was used to conduct the test. Fixed response and roving excitation methodology was employed for making measurement. Input force and responses were measured using SCADAS III hardware and Test. Lab software. The test results were compared with the analytical results. Test configuration, test procedure and results are documented

Vibration control studies using an impedance method

This paper presents a vibration control methodology that is useful in practical applications where the system to be controlled is difficult to model due to the presence of uncertainties or complex boundary conditions. The impedance control method uses a power flow approach wherein the controller is designed such that power flow into the structure is minimized. This is accomplished by using the dereverberated point impedance function at the actuator location for the design of the controller. The method is implemented and simulated for a cantilever beam with piezoceramic actuators. As a preliminary step towards real-time implementation of impedance control a simple state feedback algorithm is implemented using a dSPACE digital signal processor (DSP) card

Ground Resonance Testing of 500 kW Wind Turbine GFRP Blade

Ground Resonance Test is essential to determine the dynamic characteristics, such as Natural Frequencies, Modal Damping, Mode shapes and MAC Matrix. The 500 kW Wind turbine GFRP blade was subjected to GRT in order to find the dynamic characteristics experimentally. The wind turbine GFRP blade was rigidly attached to the static test rig in order to simulate the cantilever boundary condition. SISO test technique was used to conduct the test. Fixed response and roving excitation methodology was employed for making measurement. Input force and responses were measured using SCADAS III hardware and Test. Lab software. The test results were compared with the analytical results. Test configuration, test procedure and results are documented

Flutter prediction of a transport aircraft from ground vibration tests

Flutter characteristics of a high T-Tail transport aircraft has been estimated using experimental modal parameters from ground vibration tests. Infinite plate extrapolation schemes have been used to map the obtained eigen-vectors from the test points on the aircraft to an equivalent refined finite element mesh model of the aircraft. A Direct Matrix Abstraction Program (DMAP) written for NASTRAN software, carries out a normal modes analysis for arbitrary material properties and replaces the generated mass normalized eigen values and vectors with the experimental values. The flutter solution has been carried out by the P-K method in the flutter module of NASTRAN. The effects of variation in the frequencies, on the predicted T-Tail flutter speed using experimental modal parameters has been compared with the flutter speeds obtained from the finite element model consisting of the actual design details, material and mass distributions of the transport aircraft

In-flight vibration and temperature measurements on a typical aircraft for test tailoring

Test tailoring is a methodology to develop indigenous vibration qualification spectrum for Line Replaceable Units (LRUs) of a typical fighter aircraft based on actual measurements. Data from flight measurements plays a major role in test tailoring approach as the uncertainty factors in measurement process affect the spectrum generated and hence the survivability of LRUs in such environments is reliable. The vibration data generated is used to develop vibration qualification spectrum where as the temperature data is used to qualify the rubber hoses especially at the lower temperature range. The measurement process of such environment involves the proper selection of test points, measurement locations, In-flight Data Acquisition System, Sensors and design of mounting brackets. Since the measurements were performed on flying aircraft safety factors in terms of airworthiness of, additional aggregates were taken care. The test points were suitably dovetailed in about six flights. The data were collected for all the sorties on event basis and synchronized with onboard FDR data. The typical aircraft was a twin fin multi role combat fighter. The maximum vibration levels were observed at wing tip, fin tip, fin root and near pylon in line with expected results. This paper presents the methodology adopted for measurement of in-flight vibration and temperature data required for specification development through test tailoring. The paper briefly describes the architecture of the in-flight data acquisition system, instrumentation scheme, requirements and specification of sensors, the identification of measurement points on the aircraft, design and fabrication of bracketaries required for mounting IFDAS and sensors, details of test points that have bearing on vibration and temperature, in-flight data acquisition and quick look analysis of data. The vibration data were collected at 12 locations in all three directions and thermal data were collected at 6 locations

Potential use of plant proteolytic enzymes in hemostasis

The aim of this chapter is to review the development and state of the art in the application of plant proteases, and their effects on hemostasis. Reviewing the proteases that inhibit or enhance platelet aggregation, blood coagulation and fibrinolysis. The ultimate goal is the use of these plant proteases to improve current therapies and overcome drawbacks and deficiencies of the current drugs associated mainly with bleeding disorders. Different methods of extraction and identification have been investigated. Some effects of the identified proteases have been evaluated. We give here an overview of the latest advances in the identification and application of proteases in hemostasis.Fil: Pepe, Alfonso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Tito, Florencia Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Guevara, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin