Abstract:
The increasing enrollment of students in higher institutions of learning in Nigeria demands higher capital expenditures, which either in some cases are not available or grossly insufficient, to provide essential machines and equipment for the training of professional engineers and technologists. Consequently, torsion test is often overlooked despite its importance in the investigation of mechanical properties for automobile, manufacturing, and bio-medical engineering products.
An indigenous bench-top manual torsion testing machine was developed to perform pure torsion test on metal rods. The machine provided information on the shear properties of the materials being tested upon which shear moduli were determined. The machine was produced predominantly by fabrication method coupled with machining and casting processes. The various materials of production included mild-steel, aluminium, cast-iron, tool-steel, and polymer.
Torsion test was conducted, using the machine so developed in this work, on Aluminium and Brass specimen with 5 mm diameter, respectively; and 5.5 mm diameter of Mild-steel. The experimental shear moduli from the test shown that Aluminum has 23,205.92 N/mm2 (16% less than expected), while Brass has 21,498.06 N/mm2, (43% less than expected) and Mild-steel has 15,773.10 N/mm2(80% less than expected).
The results suggested a re-investigation into the load measuring unit, as the applied torque load may be higher than the one being measured. However, a simple practical approach is being made to demonstrate torsion test for teaching purposes.
