At the end of this section you should be able to:

1. Create FBD for internally-cut systems in 2D and 3D

   • Use standard convention for directions of forces in beams

2. Use FBD to create equations to solve for internal loads

Internal Loads shows how to find the internal force and internal moment resultants at a specific location in a member by using the cut-section approach. You will practice making an internal cut, drawing a correct free body diagram of the internally cut system in 2D and 3D (including the standard sign convention for beam internal forces), then writing equilibrium equations from the FBD to solve for the unknown internal loads. Practice examples include point loads, distributed loads, rope-supported members, frames and machines with distributed loading, and 3D cases with common support hardware, with Mathematica code provided to help set up and solve the equations efficiently.