Calculix, FEA, et al.

https://www.youtube.com/watch?v=wAJe1R5NDGw

FreeCAD FEM/Civil/Structural/Arch Tutorial-1-An Introduction

https://www.youtube.com/watch?v=OVd5j71cdXM

CalculiX Launcher 3beta - Bolted Connection ( non standard) with contact and bolt preload

https://www.youtube.com/watch?v=VA0eg0LWfWM

CalculiX is a different program than Code Aster

https://www.youtube.com/watch?v=7p5mQuJIZdI  (simulation of a beam with Code Aster)

https://www.youtube.com/watch?v=rOjhvq_TnpY

https://www.youtube.com/watch?v=9Ztbq4gLf0w