The Three Node Quad

Depending on your experience with finite elements, this post will either be totally obvious or it will blow your mind. The standard bilinear, isoparametric four node quad element degenerates to a three node constant strain triangle when you assign two consecutive element nodes to the same location. This fun fact is due to the math, … Continue reading The Three Node Quad →

Hidden Fees

Helper functions are often implemented as private methods in a class. For example, here is a private cross product function in an Element class of OpenSees. Vector CadillacBeamColumn3d::cross(Vector v1, Vector v2){ Vector v3(3); v3(0) = v1(1)*v2(2)-v1(2)*v2(1); v3(1) = v2(0)*v1(2)-v1(0)*v2(2); v3(2) = v1(0)*v2(1)-v1(1)*v2(0); return v3; } Note that the class name has been changed and other … Continue reading Hidden Fees →

Transformation Cross-Training

Athletes often cross-train in secondary activities in order to improve performance in their primary sport. For example, football players may practice ballet in order to improve their flexibility and endurance. Using OpenSees, you practically have to be a mathlete to understand the geometric transformation in three dimensions. But instead of fumbling your way through space … Continue reading Transformation Cross-Training →