I can identify likely tension and compression members in a simple truss and explain the load path.
POE Unit 2 • Lesson 2.7
Trusses and Member Forces
Focus question: How do triangulated structures carry loads through tension and compression members?
Mission Briefing
Today’s Plan
A focused sequence that builds toward the aerospace payload support structure challenge.
Opening promptConcept modelGuided analysisInteractive practiceEvidence checkExit ticket
Lesson Targets
What You Will Be Able to Do
Truss member-force map
The force map uses joint geometry and load direction to label members consistently and traces the load to the supports.
Activity Flow
How the Lesson Moves
Each step builds the structural reasoning needed for the lesson deliverable.
1. Identify joints and members
Treat connections as joints and members as two-force elements.
2. Trace the load
Follow the applied force through the triangular geometry to the supports.
3. Classify members
Determine which members pull in tension and which push in compression.
Lesson Interactive
Map Tension and Compression in a Simple Truss
Classify the three members in the symmetric triangular truss under a downward load at the top joint.
Triangular Truss
Assume ideal pin joints and loads applied only at joints.
Classify Members
| Member | Force type |
|---|---|
| AB left diagonal | |
| BC right diagonal | |
| AC bottom chord |
The diagonals push outward under the top load; the bottom chord prevents the supports from spreading.
Today’s Work
Main Deliverable
Truss Force Map
Annotate one simple truss under a specified load.
- Label the applied load, support reactions, and load path.
- Identify members in tension and compression and justify at least one classification.
Exit Ticket
Mission Debrief
State one structural idea from today in your own words.
Name one calculation, measurement, diagram, or observation that could support a design decision.
Identify one question or risk to carry into the next structural lesson.
Resources
Lesson Resources
Lesson 2.7 PowerPoint
Use the presentation to review the lesson concepts, examples, and activity directions.
Principles of Engineering
Return to the POE course hub for units, resources, certifications, and current course information.
Aerospace Payload Support Structure
Use this unit project context when connecting analysis, material decisions, prototype testing, and final design-review evidence.