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
Here is a method for converting modal damping to a damping coefficient matrix for all modes. It is based on a pseudo inversion of the modal damping matrix. The resulting coefficient matrix will be fully populated. The damping terms will not necessary corresponding to physical dashpots,… 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
A vibration absorber is a tuned spring-mass system which reduces the vibration of a harmonically excited system. Here is a paper for an applied force: Vibration Absorber Here is a Matlab script and its supporting function: vibration_absorber_trans.m mratio.m * * * Here is a paper… Read more
In Holland during World War II, the Casper ten Boom family used their home as a hiding place for those hunted by the Nazis. This was their way of living out their Christian faith. Four members of the family lost their lives for providing this… Read more
Good Timber by Douglas Malloch The tree that never had to fight For sun and sky and air and light, But stood out in the open plain And always got its share of rain, Never became a forest king But lived and died a scrubby… Read more