In this lecture, we'll cover:

• How to implement the previously defined member force function within our main analysis script
• How to extract the relevant global nodal displacements for each element
• How to transform global displacements into local member forces
• How to call the function for each truss member and interpret the output
• How to format and present axial member forces clearly in kN

In this lecture, we focus on calculating the axial forces in each truss member using the global displacement vector we have already obtained. We begin by reusing the member force function developed earlier, which takes material properties, geometry, orientation and nodal displacements as inputs. We recall that the nodal displacements are expressed in the global reference frame and are internally transformed into the local member coordinate system before computing the axial force.

We then step through how to call this function for each individual member. This involves carefully extracting the correct displacement components from the global displacement vector and passing them in the correct order for the start and end nodes of each element. Once the function returns the axial force, we assign it to a variable, format the output, convert the result into kN, and apply rounding for clarity. After verifying the result for one member, we repeat the same structured process for the remaining members of the structure.

Overall, we reinforce that this procedure is a direct extension of what we previously implemented for a simpler two-bar truss. The key idea is that once the global displacements are known, computing member forces becomes a systematic and repeatable task of function calls and careful indexing.

Next up:

In the next lecture, we visualise the results by plotting the undeformed and deformed shapes of the 8-bar truss, reusing and extending our earlier plotting approach.