Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  • Users: E2015
  • Order by date
  1. E2015

    Mode Shapes calculated in Matlab Toolbox MACEC 3.3

    Thank you for your reply. Actually I can plot the mode shapes within the toolbox. The animation of the mode that I get within the toolbox looks like this: However, I have to save the mode shape vector and plot it outside the toolbox environment. But in that case I don't know how to deal with...
  2. E2015

    Mode Shapes calculated in Matlab Toolbox MACEC 3.3

    Dear all, I am using Matlab Toolbox MACEC 3.3 for EMA of a railway sleeper (both concrete and timber). The resulting mode shapes I obtain are unity scaled modal mass mode shapes and they appear as complex numbers. For each mode calculated I also have information about Modal phase...
  3. E2015

    Zero offset, zero drift or something else?

    Here are the plots of force and acceleration with x-axis representing time in seconds. Figure 1 Force Figure 2 Force Zoomed IN Figure 3 Acceleration Figure 4 Acceleration Zoomed IN Are the jumps in between impacts, or settling in the data for hammer and accelerometers in between impacts...
  4. E2015

    Zero offset, zero drift or something else?

    I have some strange readings from an impact hammer and acceleromeeters. The hammer is from Piezotronics PCB Model 086D50 and the accelerometers are from Dytran model 3333A and 325M24. On the first picture called Force you can see the plotted force magnitude in Newtons with number of samples. I...
  5. E2015

    Impact hammer test - Modal Parameters Extraction from multiple FRFs

    The freq resolution is 0.1526 (Fs/NFFT). The sampling rate was 5kHz and the acceleration/force signals were 6.3002 seconds long (31501 samples). Thanks, Emina Emina B.
  6. E2015

    Impact hammer test - Modal Parameters Extraction from multiple FRFs

    Thank you Greg for looking at the data. Can you just say what is the deltaF you have calculated and plotted? Sorry for the .mat file, I'll bear in mind the .txt next time when sharing the data. In reality I should get following modes: 1st around 30Hz, 2nd around 50 or 60Hz, 3rd mode around...
  7. E2015

    Impact hammer test - Modal Parameters Extraction from multiple FRFs

    Thank you Jason for the advice. (I don't know why I haven't seen your answer before.) At the moment I am the only one in my department trying to work on modal analysis, so I am afraid I am alone in this. But anyway there are good books on this topic, it's just sometimes difficult to find one...
  8. E2015

    Impact hammer test - Modal Parameters Extraction from multiple FRFs

    Thank you Greg for your reply. I am doing the modal analysis for the first time, so I am not experienced in the testing itself but I am giving my best to find a way how to deal with Modal Analysis for my application. But getting the full matrix is leading to more confusing data set I must...
  9. E2015

    Impact hammer test - Modal Parameters Extraction from multiple FRFs

    I have done an impact test on a railway sleeper which was embedded into railway ballast. I did impacts at 11 points along the sleeper, and I have gathered acceleration for each of the impacts at 11 points of the sleeper, i.e. I had 11 impact/reference points and 11 response points...
  10. E2015

    Exciting lower modes of an embedded concrete beam

    Dear all, I have tested a concrete beam that is embedded into layer of gravel (100 mm thick). I have looked only at vertical direction. The accelerometers are positioned on top of the beam and the impact was applied as close as possible to the positioned accelerometers. In total I have used 10...
  11. E2015

    Filtering data from impact hammer test

    This is the autopower spectrum of the force for impact on top of the sleeper I have used a soft tip, brown color. Also my interest now is for frequencies under 1000Hz. The following figures show FRF, pahse and coherence for two accelerometers and impact on on top of the sleeper. Also, I have...
  12. E2015

    Filtering data from impact hammer test

    I have attached data I acquired for one sleeper in time. Both force and acceleration are presented. Fig 1. Force and Acceleration for all impacts and all channels Fig 2. Force and acceleration for impact at sleeper right end side Fig 3. Force and accleration for impact at sleeper right end...
  13. E2015

    Filtering data from impact hammer test

    Dear all, I have acquired some data by using instrumented hammer and 8 accelerometers. The data has been acquired on a railway track on a timber sleeper. Now, I want to analyse the data in the frequency domain. Usually I am interested in the lower frequency range up to 1000Hz. When I...
  14. E2015

    How to define modal strain energy?

    Hi! When we define modal strain energy, is it done separately for translational and rotational modal displacements? I am looking on a paper where they use Modal Strain Energy Criterion in FEM crack detection in beams. They use an expression like: MSEij=1/2*PhiTij*Ki*Phiij, where: PhiTij refers...
  15. E2015

    Abaqus Training

    Hi! Did anyone had experience with training courses in Abaqus? What is the approximate price per training? I am just starting with Abaqus, so I need a good introduction. I contacted Dassault Systèmes by email for this, but still didn't received any reply. If someone could share experience would...
  16. E2015

    Modal Nodal Forces-FEM-Matlab

    Hi, I am looking at natural frequencies and mode shapes of Timoshenko beam in Matlab. For the analysis I used FEM. I had translation and rotation at each node, 4DOF per element. I need to calculate MODAL NODAL FORCES, expressions: ke * phi and K * PHI. ke * phi refers to element level and K...
  17. E2015

    Experimental Modal Analysis

    Thank you GregLocock and Amanuensis for your comments and suggestions. I have done the roving hammer method with eight impacts. Now my results show some sense what means that peaks of the FRF are visible and they correspond to values of natural frequencies. The values of first two peaks are...
  18. E2015

    Experimental Modal Analysis

    Hi GregLocock, Thank you for your answer. I'm at a learning stage of EMA, that's why I'm struggling that much. "square force" in my example is force of 25N magnitude and total duration of 0,5 sec. Since I don't have a real recordings from an impact, I have used force of a square shape just for...
  19. E2015

    Experimental Modal Analysis

    Hi everybody, Can anyone comment my work, since I'm new in this are? I'm trying to perform SIMO analysis in MAtlab. I have done an analysis of Euler-Bernouli beam subjected to square force in the middle of the beam in Matlab. Using Wilson's Theta numerical integration method I have calculated...
  20. E2015

    Modelling impact force in MATLAB

    Does anybody know how to model impact force at certain location on the beam in MATLAB by using FEM? I need to obtain dynamical response of Timoshenko beam in MATLAB when it’s subjected to impact force, e.g. square force shape in the middle of the beam. I’m using FEM and Wilson’s Theta method...

Part and Inventory Search

Back
Top