Thin layers of adhesive, plastic, or rubber are often employed in precision machines for joining, shimming, and sealing. These layers are often the most compliant and most dimensionally unstable elements of an assembly, so it is important to understand their behavior.

Continue reading Expansion and Stiffness of Thin Adhesive or Rubber Layers →
Microslip in rolling motion is often very complicated, but the net effect can sometimes be estimated pretty easily based on strain and the resulting changes in velocity.

Continue reading Strain, Speed, and Microslip →
The power spectral density (PSD) is one of the primary ways we characterize random or broadband signals. In many cases, a PSD is read from a signal analyzer and used qualitatively to describe the frequency content of a signal. But to do anything quantitative with a PSD, we need to understand its units.
Continue reading Units of Power Spectral Density →
Most people interested in machines know that adding a slight crown to a pulley tends to keep flat belts centered. But it is not obvious how it works.

Continue reading How Crowned Pulleys Make Belts Track →
Paraview is a very powerful tool for post-processing and displaying data, especially from FE or CFD simulations. But because it typically acts on the mesh without the underlying geometry, it doesn’t inherently know about the edges of parts or volumes. In this post, I run through the steps to detect the edges and draw them as a wireframe.

Continue reading How to Get Part Edges to Show in Paraview or ParaFOAM →
notes on mechanics, machine design, and analysis