The flight accelerometer data was measured on a launch vehicle which shall remain anonymous. This was due to an oscillating thrust vector control (TVC) system during the burn-out of a solid rocket motor. This created a “tail wags dog” effect. The resulting vibration occurred throughout… Read more
Response Spectrum Response spectrum is a plot of the maximum responses (acceleration, velocity, or displacement) of idealized single-degree-of-freedom oscillators as a function of the natural frequencies of the oscillators for a given damping value. The response spectrum is calculated for a specified vibratory motion input… Read more
Launch vehicle avionics components must be designed and tested to withstand random vibration environments. These environments are often derived from flight accelerometer data of previous vehicles. This data tends to be nonstationary as shown in the figure above. The typical method for post-processing is to… Read more
The most widely used algorithm for the Shock Response Spectrum (SRS) calculation for base excitation is the ramp invariant digital recursive filtering relationship given in: David O. Smallwood, An Improved Recursive Formula for Calculating Shock Response Spectra, Shock and Vibration Bulletin, No. 51, May 1981.… Read more
It appears GotoBLAS2 has been deprecated (i.e. orphaned). The new standard is OpenBLAS. OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version. OpenBLAS is an open source project supported by Lab of Parallel Software and Computational Science, Institute of Software Chinese Academy… Read more
Modal Transient Analysis of a System Subjected to an Applied Force via a Ramp Invariant Digital Recursive Filtering Relationship: force_ramp_invariant.pdf Reference Papers: Smallwood Irvine General Coordinate Irvine Impulse Response Function 1 Irvine Impulse Response Function 2 Irvine SRS * * * * * * * * * *… Read more
Here are links, with an emphasis on aerospace careers. Huntsville, Alabama http://www.huntsvillealabamausa.com/new_exp/crp/companies/alphabetical_list.html http://www.huntsvillespaceprofessionals.com/ http://nasajobs.nasa.gov/jobs/msfc.htm http://www.asmartplace.com/getsmart/work_findajob.html http://www.al.com/jobs/ Elsewhere http://www.usajobs.gov/ https://jobs-orbital.icims.com/jobs/intro?hashed=0 http://www.ulalaunch.com/site/pages/Careers.shtml http://www.aerojet.com/careers/ http://www.jhuapl.edu/employment/default.asp http://www.ata-engineering.com/careers http://www.spacex.com/careers.php http://www.blueorigin.com/careers/careers.html http://www.sdl.usu.edu/employment/ www.navyjobs.com http://www.aerospacetestingalliance.com/ Tom Irvine
I have posted the January 2012 Newsletter at: http://www.vibrationdata.com/newsletters.htm The topics are: Slow Earthquakes Rumbler Siren Shepard Tones Toadfish Mating Call There are seven accompanying sound files and one Matlab script. Please let me know if you have any questions. Thank you, Tom Irvine
Here is a Fortran program which solves a system of linear equations: LIN_EQ.F It is compiled via: gfortran -o LIN_EQ LIN_EQ.F -llapack The program uses the LAPACK subroutine: DGESV * * * A version written in C/C++ is given at: linear_eq.cpp It is compiled via: gcc… Read more
Introduction Message Passing Interface (MPI) is a portable library of subprograms which can be used to facilitate parallel computing. The MPI subprograms can be called from C and Fortran programs. Parallel Computing Parallel computing enables large scale numerical problems to be solved in a timely… Read more