We held our first Shock & Vibration Webinar on January 17, 2014. This presentation was sponsored by the NASA Engineering and Safety Center, to which I express gratitude. A link to the audio/visual recording will be posted here in the near future. In addition, here… Read more
Here is a paper which gives a derivation of the mass and stiffness matrices for beam bending: beam_FEM.pdf * * * Here is a Matlab script for the modal analysis of a straight beam. beam.zip * * * Here is Matlab script for the modal… Read more
This set of scripts calculates the response of an SDOF system to an applied force PSD. A transfer function is derived. Then its square is applied to the force PSD to calculate the response, using point-by-point multiplication and integration. sdof_ran_force.zip Important note: The following scripts… Read more
Here is a C++ program which generates random numbers for a user-selected distribution. monte_carlo_random.cpp monte_carlo_random.exe The distribution options are: 1. Uniform 2. Normal 3. Rayleigh 4. Weibull 5. Gumbel 6. Binomial The random numbers can then be used in a Monte Carlo analysis. * *… Read more
The Newmark-beta method can be used to solve structural dynamics problems in the time domain, of the form: M (d^2x/dt^2) + C dx/dt + K x = F This method performs direct integration on the mass, damping and stiffness matrices which may be fully-coupled. Here… Read more
The Newmark-beta method can be used to solve structural dynamics problems in the time domain, of the form: M (d^2x/dt^2) + C dx/dt + K x = F This method performs direct integration on the mass, damping and stiffness matrices which may be fully-coupled. Here… Read more
One of my responsibilities to NASA is to provide training sessions and materials as an outreach to the engineering community. Occasionally, I provide onsite training, but these classes are becoming increasingly difficult to organize for a variety of reasons. As an alternative, I am considering… Read more
A number of methods have been derived for performing rainflow cycle counting for a response PSD. Note that they tend to be conservative. The Dirlik method is an example of a semi-empirical method for cycle identification. A Matlab script for performing this method is given… Read more
The Newmark-beta method can be used to solve structural dynamics problems in the time domain, of the form: M (d^2x/dt^2) + C dx/dt + K x = F This method performs direct integration on the mass, damping and stiffness matrices which may be fully-coupled. Here… Read more
A transfer function is a type of frequency response function (FRF) that gives the steady-state response to a force input as a function of frequency. Transfer functions for structural dynamics problems can be calculated from the natural frequencies, modal damping ratios and normal modes. This… Read more