Experiment: Testing the strength of various joints

Aim: To test the strength of various joints in beams

Materials:  pieces of metal,poplar wood, glue, drawing pins/nails, bolts and nuts, old plastic rulers, burner, bricks/clamp, welding equipment/burner

Method

Testing the strength of a joint

1. Use poplar wood of sufficient thickness to prevent fractures from other parts of the wood causing failure during the testing process
2. Make various types of joints: scarf and lapped joints
3. The slope(in scarf joints) and area of the joints can be varied
4. The material used co join the pieces to be tested can also be glue, rivets, nails or welding
5. Join two pieces of wood/metal using any of the material and techniques above
6. A burner can be used to weld two pieces of metal together
7. Put the joined beam on a table and fix it in place using bricks
8. Find the load required to break each joint

Observations and results

• Rivets are the strongest pinning
• Welding/Gluing are less stronger than pinning (nailing, bolting, riveting)
• Increasing the area of overlay makes the joints stronger
• A much more gentle slop in scarf joints increases the strength of the joints

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