Combined Bending and Torsion Apparatus

The combined bending and torsion apparatus is a robust educational solution designed to help students explore elastic failure in materials under combined bending and torsional loads. Ideal for undergraduate and higher education strength of materials courses, this experiment introduces students to real-world material behaviour and failure theories in a clear and hands-on manner.

The apparatus features precision-machined “necked” specimens made from round bar stock. These are clamped securely at one end to a sturdy base plate, while the other end is connected to a counterbalanced circular loading plate. The counterweight system ensures the specimen remains unloaded before testing begins, improving accuracy and safety.

The loading plate is clearly marked at 15° intervals and includes indents for secure hanger placement. This allows students to apply pure bending, pure torsion, or a controlled combination of both, enabling direct comparison with different theoretical failure models.

Specimen deflection is accurately measured using a dial gauge placed diametrically opposite the load application point. For added safety, set screws beneath the base plate limit any excessive movement in the event of specimen failure.

This solution is an essential tool for demonstrating complex failure modes and deepening student understanding of mechanical stress and material limits.

Learning Objectives:

• To determine elastic failure of a specimen subjected to several ratios of bending and torsion simultaneously​
• To compare the results with the established theories of failure