admin I am taking a class in continuum mechanics at the University of Alabama in Huntsville. Here are some notes: Derivation of the Epsilon-Delta Relationship: epsilon_delta.pdf Continuum Mechanics Formulas (Kronecker delta, permutation symbol, dot product, cross-product, etc.) : cm_formulas.pdf Del Operator Proofs (divergence, curl, cross-product, etc.):… Read more
Some U.S. states allow semi-trucks with three trailers. The truck configuration can total up to 105 feet by adding a rear trailer. Terry Sumter, a UPS driver for 30 years, has experienced the back trailer moving into the oncoming lane. “The most significant condition is… Read more
Curiosity is a car-sized robotic rover exploring Gale Crater on Mars as part of NASA’s Mars Science Laboratory mission (MSL). Curiosity was launched from Cape Canaveral on November 26, 2011 aboard the MSL spacecraft and landed on Aeolis Palus in Gale Crater on Mars on… Read more
The following is based on a description from Dennis Kern, NASA/JPL, which Isam Yunis, NASA Langley, referenced in a shock presentation. Shocks travel through structure as a combination of propagating waves and vibration response, with the vibration response concentrated more in lower frequencies and the… Read more
I will present two tutorials sessions at the Shock & Vibration Symposium. Here are the slides: Shock Response Spectra & Time History Synthesis SAVE_conference_2014_Irvine_shock.pptx Rainflow Cycle Counting for Random Vibration Fatigue Analysis SAVE_conference_2014_Irvine_fatigue_revA.pptx * * * Here is the Matlab GUI multi-function signal analysis package:… Read more
PowerPoint Slides: webinar_36_fatigue_nonGaussian_random.pptx Audio/Visual File NESC Academy Non-Gaussian Random Fatigue and Peak Response – Recommend viewing in Firefox with Sliverlight Plugin * * * References: Rainflow Fatigue Posts Generating Random Time Histories with User-specified Skewness & Kurtosis * * * Matlab script: Vibrationdata Signal Analysis Package *… Read more
I have added a function for generating random time histories with user-specified skewness & kurtosis to the Vibrationdata Matlab Signal Package posted at: Vibrationdata Matlab Signal Analysis Package The function includes an option for band-limiting the signal via lowpass filtering. Tom Irvine
PowerPoint Slides: webinar_35_fatigue_sine_random.pptx Audio/Visual File: NESC Academy Using Fatigue to Compare Sine and Random Environments – Recommend viewing in Firefox with Sliverlight Plugin * * * References: Steinberg’s Vibration Analysis for Electronic Equipment Sine and Random Vibration Equivalent Damage Rainflow Fatigue Posts * * * Matlab… Read more
PowerPoint Slides: webinar_34_rainflow_fatigue_beam.pptx Audio/Visual File: NESC Academy Rainflow Fatigue for Continuous Beams – Recommend viewing in Firefox with Sliverlight Plugin * * * References: Steinberg’s Vibration Analysis for Electronic Equipment Rainflow Fatigue Posts * * * Matlab script: Vibrationdata Signal Analysis Package * * * See also:… Read more
NASA-STD-5019, Fracture Control Requirement for Spaceflight Hardware (excerpt) 4.1.1.12 Low-Risk Part This section addresses parts that can be classified non-fracture critical because of large structural margins and other considerations that make failure from a pre-existing flaw extremely unlikely. a. For a part to be classified… Read more