Hello All,
I am very much out of my comfort zone of knowledge.. I am an undergrad mechanical engineering student, and I am searching for free or cheap software that can help me find modes and frequencies of a sample sized beam, and then I need software to help me figure out how much deflection is occuring at the mid span of a CNC structural beam. What I have so far :
2 B&K peizo electric Accelerometers, 1 charge amplifier, shielded wiring - provided by university
I need the software, preferably portable on my own laptop, or another. We have matlab here but not the toolbox for signal processing or DSP. I have a matlab license as a student.
First off, I would like to know to know what processing type do I need? signal, dsp, or etc? Is spectrium analysis the same as signal processing?
Then, advice on which software. My university has Labview but its not portable.
For the modal analysis test - I will be building my own DIY impact hammer. I have found a great design report on how to make one very cheap. Then, I will be taking a beam section ( if no portable software is available) mounting it, and completing a "roving hammer" test.
For the beam, I will have to build a frame, and use dc motors with brakes to simulate the CNC structural beam translating then stopping to make a 90 deg cut. The issue here is deflection/vibrational amplitude is causing roughness in cuts with loss of accuracy. If I can locate a strong portable software then I can go to the CNC machine, and measure it.
Thanks,
Andrew
I am very much out of my comfort zone of knowledge.. I am an undergrad mechanical engineering student, and I am searching for free or cheap software that can help me find modes and frequencies of a sample sized beam, and then I need software to help me figure out how much deflection is occuring at the mid span of a CNC structural beam. What I have so far :
2 B&K peizo electric Accelerometers, 1 charge amplifier, shielded wiring - provided by university
I need the software, preferably portable on my own laptop, or another. We have matlab here but not the toolbox for signal processing or DSP. I have a matlab license as a student.
First off, I would like to know to know what processing type do I need? signal, dsp, or etc? Is spectrium analysis the same as signal processing?
Then, advice on which software. My university has Labview but its not portable.
For the modal analysis test - I will be building my own DIY impact hammer. I have found a great design report on how to make one very cheap. Then, I will be taking a beam section ( if no portable software is available) mounting it, and completing a "roving hammer" test.
For the beam, I will have to build a frame, and use dc motors with brakes to simulate the CNC structural beam translating then stopping to make a 90 deg cut. The issue here is deflection/vibrational amplitude is causing roughness in cuts with loss of accuracy. If I can locate a strong portable software then I can go to the CNC machine, and measure it.
Thanks,
Andrew
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There are so many larger forces at play in this equation than the dynamic motion of the beam coming to a stop. And the major players are not going to be easy to simulate. Your average CNC machine is going to be around 10HP at the spindle, high spindle rpm (15,000 RPM) and cutter load chewing chips out of a hunk of steel -- all of 'em orders of magnitude higher than structural beam deceleration, stepper motor vibrations, etc.
Unless this is a little desktop thing.
If you have the chance to instrument the real thing, as opposed to simulating various things, go for it. And get another accelerometer, because things move in 3D.
Do a little reading on CNCzone or PracticalMachinist forums. Use Google to search the sites, because the forum search function isn't good. There are so many variables involved in smoothness of finish/cut, it's crazy. In addition to those mentioned above, machine axis wear, spindle wear, coolant/lubricant, number of flutes on mill, feedrate, speed of spindle, depth of cut/chipload, part resonances, etc. Oh, and rigidity of machine.
Chip
Unless this is a little desktop thing.
If you have the chance to instrument the real thing, as opposed to simulating various things, go for it. And get another accelerometer, because things move in 3D.
Do a little reading on CNCzone or PracticalMachinist forums. Use Google to search the sites, because the forum search function isn't good. There are so many variables involved in smoothness of finish/cut, it's crazy. In addition to those mentioned above, machine axis wear, spindle wear, coolant/lubricant, number of flutes on mill, feedrate, speed of spindle, depth of cut/chipload, part resonances, etc. Oh, and rigidity of machine.
Chip
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