Vibrationdata Blog - Page 16 of 43

Boeing 717-200

April 22, 2015 by admin

I recently flew as a passenger on a Boeing 717-200 aircraft similar to the one shown in the image. This aircraft has two Rolls-Royce BR700 engines, with the following specifications: Maximum Engine Rotational Speeds (Both Engines) N1 Low Pressure Turbine = 6,195 RPM (103 Hz) N2… Read more

Digitizing Plots

April 22, 2015 by admin

Here is audio/visual file: Digitizing Plots Here are slides, Matlab scripts and data samples: Unit_33_PP.zip Here is another script: digitize_plots.m This is vintage presentation. I need to add the Matlab scripts to the Vibrationdata GUI package. – Tom Irvine

Notes on Fatigue for Pure Compression Stress

April 10, 2015 by admin

Fatigue is usually associated with tensile stresses. Engineering knowledge of compressive fatigue is very limited. Compression stresses do not cause cracks, but plastic compressive strain can cause tension stresses when the load is returned to zero and the resulting tension stress causes cracks. * *… Read more

Webinar 48 – Rainflow Cycle Counting for Multiaxial Stress

March 10, 2015 by admin

Slides: To be added before 4/4/2015 This unit gives a method for converting a time-varying stress tensor into a weighted-average equivalent uniaxial stress. The weights are chosen to maximize the fatigue damage. * * * Matlab script: Vibrationdata Signal Analysis Package * * * Reference… Read more

Webinar 47 – Shock Response Spectrum Synthesis, Special Topics

March 7, 2015 by admin

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

Webinar 46 Two-degree-of-freedom System with Multi-point Enforced Motion

February 19, 2015 by admin

Slides: webinar_46_two_dof_multipoint.pptx * * * Matlab script: Vibrationdata Signal Analysis Package * * * Reference Paper: two_dof_enforced_motion_multipoint.pdf * * * See also: Two-degree-of-freedom Systems * * * – Tom Irvine .

Temporal Moments

February 18, 2015 by admin

Temporal moments are sometimes used for shock analysis. Here is a Matlab script: temporal_moments.m References: Hemez & Doebling, From SRS to Temporal Moments J. Cap & D. Smallwood, A methodology for defining shock tests based on shock response spectra and temporal moments See also: Energy… Read more

Fixed-Fixed-Fixed-Fixed Plate, Fundamental Vibration Mode

February 13, 2015 by admin

The plate is aluminum, 0.063 inch thick. The fixed edge lengths are 6 and 4 inches. The vibration mode was calculated via the Rayleigh method using an assumed displacement function, as carried out via Matlab script: fixed_fixed_fixed_fixed_plate.zip The method is given in: fixed_fixed_fixed_fixed_plate.pdf See also:… Read more

Webinar 45 – Two-degree-of-freedom System with Rotation and Translation

February 13, 2015 by admin

Slides: webinar_45_two_dof_trans_rot.pptx Audio/Visual File: NESC Academy Two-degree-of-freedom System with Rotation and Translation – Recommend viewing in Firefox with Sliverlight Plugin * * * Matlab script: Vibrationdata Signal Analysis Package * * * Reference Papers Sample Automobile Vibration Problem: auto.pdf Spring-Mass System Subjected to Enforced Motion:… Read more

NASGRO Coefficients

January 27, 2015 by admin

The following scripts calculate the A, B, C, P coefficients to model a set of SN curves with varying R values: sin_curve_fit_R.zip sn_curve_fit_R.m is the main script. The remaining scripts are supporting functions. The equations are given in: sn_curvefit_equation.pdf * * * References: 1. MIL-HDBK-5J… Read more