SINE-SWEEP MEASUREMENTS SOFTWARE FOR ANDROID AND iOS APPS ECOSYSTEMS

2021 ◽  
Author(s):  
D Griffiths ◽  
L Ausiello
Keyword(s):  
Sine Sweep

Spectral analysis of sine-sweep vibration: A fatigue damage estimation method

2021 ◽  
Vol 157 ◽  
pp. 107698
Author(s):  
M. Palmieri ◽  
F. Cianetti ◽  
G. Zucca ◽  
G. Morettini ◽  
C. Braccesi
Keyword(s):  
Spectral Analysis ◽  
Fatigue Damage ◽  
Estimation Method ◽  
Damage Estimation ◽  
Sine Sweep

The Experimental Research of Vibration Isolation Performance of MR Isolator at High Temperature

2012 ◽  
Vol 184-185 ◽  
pp. 525-528 ◽  
Author(s):  
Hui Yan ◽  
Liang Chen ◽  
Hong Rui Ao ◽  
Hong Yuan Jiang
Keyword(s):  
Vibration Isolation ◽  
Evaluation Index ◽  
Structural Parameter ◽  
Sweep Frequency ◽  
Frequency Test ◽  
Metal Rubber ◽  
Performance Evaluation Index ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Sine Sweep

Transmissibility is the main performance evaluation index of Metal Rubber (MR) isolator, which can be got by sine sweep frequency test. At different temperature, the sine sweep frequency test is done with different structural parameter MR isolator. The influence that relative density and pre-deformation have on transmissibility and natural frequency when temperature changed is analyzed. The changing regularity of MR isolator’s transmissibility at different temperature is explored. Research results provide the basis for designing MR isolator.

Free-span identification of buried gas pipe subjected to sine sweep load in pipe

Measurement ◽  
2020 ◽  
Vol 163 ◽  
pp. 108020
Author(s):  
Ningsheng Liao ◽  
Hang Zhang ◽  
Dongliang Yu ◽  
Shulu Feng ◽  
Shimin Zhang
Keyword(s):  
Sine Sweep

Spectrographic Analysis for the Modal Testing of Nonlinear Aeroelastic Systems

2006 ◽  
Author(s):  
Catharine C. Marsden ◽  
Stuart J. Price
Keyword(s):  
Nonlinear System ◽  
Time History ◽  
Modal Testing ◽  
System Response ◽  
Spectrographic Analysis ◽  
Input Frequency ◽  
Frequency Content ◽  
Aeroelastic System ◽  
Time Histories ◽  
Sine Sweep

The spectrograph is a signal processing tool often used for the frequency domain analysis of time-varying signals. When the signal to be analyzed is a function of time, the spectrograph represents the frequency content of the signal as a sequence of power spectra that change with time. In this paper, the usefulness of the technique is demonstrated in its application to the analysis of the time history response of a nonlinear aeroelastic system. The aeroelastic system is modeled analytically as a two-dimensional, rigid airfoil section free to move in both the bending and pitching directions and possessing a rigid flap. The airfoil is mounted by torsional and translational springs attached at the elastic axis, and the flap is used to provide the forcing input to the system. The nonlinear system is obtained by introducing a freeplay type of nonlinearity in the pitch degree-of-freedom restoring moment. The airfoil is immersed in an aerodynamic flow environment, modeled using incompressible thin airfoil theory for unsteady oscillatory motion. The equations of motion are solved using a fourth-order Runge-Kutta numerical integration technique to provide time-history solutions of the response of the airfoil in the pitch and plunge directions. Time-histories are obtained for the nonlinear responses of the linear and nonlinear aeroelastic systems to a sine-sweep input. The time-histories are analyzed using the spectrographic technique, and the frequency content of the response is plotted directly as a function of the input frequency. Results show that the combination of the sine-sweep input with the spectrographic analysis permits a unique insight into the behaviour of the nonlinear system with a minimum of testing. It is shown that the frequency of the nonlinear system response is a function of the input frequency and one other characteristic frequency that can be associated with the limit cycle oscillations of the same nonlinear system subject to a transient input.

Verification of Mainframe Computer Structure Finite Element Model Under Vibration and Seismic Tests

2018 ◽  
Author(s):  
Budy Notohardjono ◽  
Shawn Canfield ◽  
Suraush Khambati ◽  
Richard Ecker
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Frame Structure ◽  
Element Analysis ◽  
Physical Test ◽  
Design Cycle ◽  
Nonlinear Contact ◽  
The Finite Element Model ◽  
Sine Sweep

Shorter development design schedules and increasingly dense product designs create difficult challenges in predicting structural performance of a mainframe computer’s structure. To meet certain certification benchmarks such as the Telcordia Technologies Generic Requirements GR-63-CORE seismic zone 4 test profile, a physical test is conducted. This test will occur at an external location at the end of design cycle on a fully functional and loaded mainframe system. The ability to accurately predict the structural performance of a mainframe computer early in the design cycle is critical in shortening its development time. This paper discusses an improved method to verify the finite element analysis results predicting the performance of the mainframe computer’s structure long before the physical test is conducted. Sine sweep and random vibration tests were conducted on the frame structure but due to a limitation of the in-house test capability, only a lightly loaded structure can be tested. Evaluating a structure’s modal stiffness is key to achieving good correlation between a finite element (FE) model and the physical system. This is typically achieved by running an implicit modal analysis in a finite element solver and comparing it to the peak frequencies obtained during physical testing using a sine sweep input. However, a linear, implicit analysis has its limitations. Namely, the inability to assess the internal, nonlinear contact between parts. Thus, a linear implicit analysis may be a good approximation for a single body but not accurate when examining an assembly of bodies where the interaction (nonlinear contact) between the bodies is of significance. In the case of a nonlinear assembly of bodies, one cannot effectively correlate between the test and a linear, implicit finite element model. This paper explores a nonlinear, explicit analysis method of evaluating a structure’s modal stiffness by subjecting the finite element model to a vibration waveform and thereafter post processing its resultant acceleration using Fast Fourier Transformation (FFT) to derive the peak frequencies. This result, which takes into account the nonlinear internal contact between the various parts of the assembly, is in line with the way physical test values are obtained. This is an improved method of verification for comparing sine sweep test data and finite element analysis results. The final verification of the finite element model will be a successful physical seismic test. The tests involve extensive sequential, uniaxial earthquake testing in both raised floor and non-raised floor environments in all three directions. Time domain acceleration at the top of the frame structure will be recorded and compared to the finite element model. Matching the frequency content of these accelerations will be proof of the accuracy of the finite element model. Comparative analysis of the physical test and the modeling results will be used to refine the mainframe’s structural elements for improved dynamic response in the final physical certification test.

Modelling the Response of Force Transducers Under Sine-Sweep Calibration

2015 ◽  
Author(s):  
Nicholas Vlajic ◽  
Ako Chijioke
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Output Voltage ◽  
Frequency Response Function ◽  
Use Of Force ◽  
Applied Force ◽  
Dynamic Calibration ◽  
Force Transducers ◽  
Sine Sweep

In the dynamic calibration of force transducers using swept-sine excitation, the sensitivity (the output voltage divided by the applied force) of the transducer can start to decrease (or roll-off) at higher frequencies. It has been proposed that this roll-off originates from the finite stiffness and dissipation of the transducer. In other words, the roll-off is caused by a mechanical frequency response of the transducer, and the sensitivity is proportional to this frequency response function via a constant. The focus of this study is the origin of the observed roll-off in sensitivity. The findings of this study have application to the dynamic calibration and use of force transducers.

Nonlinear dynamic model upgrading and updating using sine-sweep vibration data

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190166
Author(s):  
T. Dossogne ◽  
L. Masset ◽  
B. Peeters ◽  
J. P. Noël
Keyword(s):  
Dynamic Modelling ◽  
Element Model ◽  
Nonlinear Behaviour ◽  
Nonlinear Dynamic Model ◽  
Vibration Data ◽  
Computational Environment ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Wing Tips ◽  
Sine Sweep

Dynamic modelling is a core activity in mechanical engineering towards supporting system and control design. It is typically carried out in a computational environment, involving idealizing assumptions of diverse kinds. The most notable assumption commonly adopted in the field is the excitation-to-response linearity of the mechanical vibrations. This common practice contrasts with the day-to-day experience of test engineers, who are ever more confronted with nonlinearities when dynamically testing modern mechanical structures. A nonlinear behaviour may result from various physical mechanisms, the most recurrent being the existence of dynamic boundary conditions in the direct vicinity of structural joints and interfaces. In this paper, a coherent set of techniques is described to locate, characterize and model nonlinearities using sine-sweep vibration data, with the purpose of upgrading a pre-existing linear numerical model into a reliable nonlinear one. A constant thread in this set of techniques is the analysis of sensor measurements in phase space. The presented tools are illustrated using acceleration time histories measured at multiple forcing amplitudes on a full-scale F-16 aircraft. Nonlinear stiffness and damping elements, modelling a loosened attachment at one of the aircraft wing tips, are identified and introduced in a linear finite-element model, leading to accurate response predictions in a strongly nonlinear regime of motion.

Synchronized sine-sweep imaging for uncoupling nonlinear signatures during pulse compression

2021 ◽  
Author(s):  
Nathalie Lamothe ◽  
Enrique Gonzalez-Mateo ◽  
Noe Jimenez ◽  
Francisco Camarena
Keyword(s):  
Pulse Compression ◽  
Sine Sweep
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