Recent content by tomirvine

What numerical engine do commercial FEA codes use for modal transient analysis? The Newmark-beta method? I have posted a paper on a ramp invariant digital recursive filtering relationship for modal analysis at: http://www.vibrationdata.com/ramp_invariant/force_ramp_invariant.pdf Please let...

Here is a paper on signal analysis: http://www.vibrationdata.com/Shock_and_Vibration_Signal_Analysis.pdf Tom Irvine

I am uncertain about the formula in your reference. But here is a tutorial which derives natural frequency formulas for various beam configurations. http://www.vibrationdata.com/tutorials2/beam.pdf Tom Irvine

Yes, ten sources with the same Sound pressure level (SPL) will and have a combined SPL that is 10 dB greater than just one source. Here is a Matlab script that can be used to demonstrate the calculation: disp(' '); disp(' add_dB.m ver 1.0 February 9, 2010'); disp(' by Tom Irvine '); % disp('...

A Fourier transform and a shock response spectrum are two different calculations. Yes, there are some roundabout, indirect, relationships between the two functions; but please consider them separate for now. I have posted a shock response spectrum tutorial at...

I have written a paper called: Shaker Table Seismic Testing of Equipemnt using Historical Strong Motion Data Scaled to Satisfy a Shock Response Spectrum It is posted at: http://www.vibrationdata.com/quake_syn.pdf I hope to present it at a conference although I have not selected one yet. I...

Can someone recommend a reference that gives formulas for analyzing the centrifugal twisting moment of a propeller blade with variable pitch? Thank you, Tom Irvine

Kyle, This idea is not ready for SolidWorks. It first needs to be tried out using a subscale prototype made from hardware store parts. Thanks for your offer of help anyway. Jim, This idea is very similar to a Hopinkson's bar. The excitation source is different as you noted. One of the...

Certain electronic components must be subjected to shock response spectrum testing, particular if the component must survive a pyrotechnic shock event while in service. (Refer to MIL-STD-1540, 810, etc.) I have an idea for a new type of shock test machine...

Refer to: Dave S. Steinberg, Vibration Analysis for Electronic Equipment Tom Irvine www.vibrationdata.com

A time history can be synthesized to satisfy a shock response spectrum. (The time history will not be unique.) Then you can perform a modal transient in FEA. Tom Irvine www.vibrationdata.com

I have posted a tutorial with some very basic information on the "added mass effect" at: http://www.vibrationdata.com/tutorials2/added_mass_fluid.pdf Tom Irvine http://www.vibrationdata.com

NEWS ALERT! Avionics components in missiles may be subjected to high-amplitude, high-frequency pyrotechnic shock pulses. The components must thus be qualified to these shock levels per MIL-STD-1540D, 810F, etc. The qualification levels often have so much margin that the tests must be...

Here is a reference paper: http://www.vibrationdata.com/tutorials2/sweep.pdf Tom Irvine

One approach is to synthesize a time history to satisfy the shock response spectrum. Then use the time history as a base input to modal transient analysis. Tom Irvine www.vibrationdata.com