1R20.20 • Tensile and Compressive Stress: Beam Bending
Location: beam supports and extra wood in/next to the Back Up Cabinet
Photo showing beam in the upright position.
Photo showing beam in the flat position.
Photos show the demonstration used at the University of Texas at Austin
Instructions / Notes:
Two stools equal in height hold the set of beam supports and are set at a distance where the end of the beam aligns with the end of support.
A third stool/stand is set up in the middle and behind the beam with the point gauge clamped to it as shown in pictures below. The weight must be hung from the center point of the beam which is indicated on each beam in red. The gauge must also measure from the center point.
Adjust height and length of point gauge stand for gauge needle to be pressed fully against desired point of deflection measurement. Zero the gauge and set to either metric or customary measurements (measurements of beams are in customary).
For each material, weight is going to be added and the deflection is to be recorded using the point gauge. The deflection should be recorded for both orientations (flat and upright) to see the difference from the second moment of inertia, I.
When strings are together, the weight simulates a point load. Otherwise, it simulates a distributed load.
Demo Staff:
As the wood beams dry out, their strength increases, resulting in little to no deflection. Therefore, it is important to spray the beams periodically hours before used in the classroom.
