The top figure is the time history from the El Centro earthquake, North-South horizontal component. The middle is the corresponding Waterfall SRS with 4 second segments and with 50% overlap. The bottom is the spectrogram. The Waterfall SRS is calculated by first taking the complete… Read more
I am trying to collect all my presentations. This is a work-in-progress… Thank you, Tom Irvine * * * * * * NAFEMS World Congress 2017 Introduction to Vibration Spectral Functions Random Vibration Vibration Fatigue Shock 1 & 2 Videos * * * * *… Read more
Equipment must be designed and tested to withstand shock and vibration. Ideally, all equipment would be tested on a shaker table with six-degree-of-freedom control (three translations and three rotations). Such tables and control systems exist but are very expensive. Furthermore, any multi-axis testing requires careful… Read more
This is a work-in-progress… I am creating a series of webinars with Matlab exercises for seismic testing. Here are the slides. Telcordia Technologies Generic Requirements GR-63-CORE: Bellcore_GR_63_Core.ppt This unit contains an alternative waveform for VERTEQII. CEI.IEC 980, Recommended practices for seismic qualification of electrical equipment… Read more
Figure 1. El Centro Earthquake 1940, Peak Pseudo Velocity, 36.4 in/sec Launch vehicle and spacecraft equipment must withstand pyrotechnic shock from stage separation and other flight events. Civil engineering structures and equipment must survive seismic events. There are many other examples where military, automotive,… Read more
My colleagues at Sandia National Laboratories have presented some conference papers recently on energy response spectrum. Here is a paper that I wrote on this topic: energy_response_spectrum.pdf Also, I have added the energy response spectrum as an option for acceleration time histories to the Vibrationdata… Read more
I am currently researching IEEE Std 693… One of its recommended shaker test methods for power equipment is to use a “sine beat” acceleration time history. The main frequency is selected as the equipment’s natural frequency. The minimum number of beats is 5 with a… Read more
Slides & Video: webinar_47_SRS_synthesis_special_topics.pptx A high-range Cummins Generator in a Seismic Shaker Test.mp4 Topics: 1. Shaker Table Seismic Testing of Equipment using Historical Strong Motion Data Scaled to Satisfy a Shock Response Spectrum 2. Temporal Moments * * * Matlab script: Vibrationdata Signal Analysis Package… Read more
Clintonville, Wisconsin is an inland community, adjacent to Lake Pigeon. USA Today reported on March 21, 2012 that a series of mysterious booms have been fraying residents’ nerves. City administrator Lisa Kuss said the booms have roused people from their beds and into the streets… Read more
The Iwate-Miyagi Nairiku earthquake struck northeast Honshu, Japan, on 14 June 2008. This earthquake had a moment magnitude Mw 6.9 according to the USGS. The peak ground acceleration (PGA) had a maximum vector sum (3 component) value of 4278 cm/sec^2 (4.36 G). This is the highest ever recorded… Read more