Structural dynamics systems can be represented in terms of mass, damping and stiffness matrices. Each of these matrices may be coupled depending on the model complexity, degrees-of-freedom, etc. The mass and stiffness matrices in the assembled equation of motion may be uncoupled using the normal… Read more
Eli was the High Priest of Shiloh and also a Judge of Israel. He was also the “Prophet.” Eli faithfully served as a father figure to Samuel. He also had the wisdom and inspiration to realize that Samuel should be the next high priest, rather… Read more
Structural system & component damping can measured via modal testing with applied force excitation. One excitation method is an impulse hammer test. Another method is a small shaker attached to structure via a stinger rod. Damping can also be measured by mounting the test unit… Read more
Structural damping depends on materials, joints, boundary conditions, friction, acoustic radiation, etc. Damping may be nonlinear, increasing as the excitation and response levels rise. The damping for a given structure or component must be measured! But here is some empirical background data… Papers Damping Properties of… Read more
For the past eight years, I have written a required monthly status report to another organization for my NASA contractor work. I have written my accomplishments and planned work in short, concise sentences, usually in numbered list format. I was then notified by this organization… Read more
Honeycomb sandwich structures are designed to have a high stiffness-to-mass ratio. The stiff, strong face sheets carry the bending loads, while the core resists shear loads. The face sheets are typically made from aluminum or carbon fiber with epoxy resin. The honeycomb core material is… Read more
John 3:16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. * * * * Psalm 136:26 O give thanks unto the God of heaven: for his mercy endureth… Read more
There is a widely-taught principle in my church that “Obedience is the first law of heaven.” This may have been an extrapolation from Alexander Pope’s quote that “Order is heaven’s first law.” But discernment must precede obedience. The Lord placed Adam and Eve in the… Read more
Aerospace pyrotechnic shock response spectrum (SRS) specifications are almost always given with an amplification factor Q=10 Corresponding time history waveforms for the base input acceleration are almost never given with the specifications Users are allowed to synthesize their own waveforms to satisfy the SRS for… Read more
Shock and vibration analysis can be performed either in the frequency or time domain The time domain method requires more computation time but is much better suited for transient and nonstationary excitation Time domain methods are also better for rainflow fatigue cycle counting Students should… Read more