ENERGY ABSORBED AT FRACTURE

A small-scale, bench-mounting, notched-bar impact tester. The equipment provides an effective, convenient and safe introduction to the principles of common impact testing techniques, enabling investigations into the resistance of materials to crack propagation.

The apparatus consists of a main unit, an instrumentation unit and a power supply. The main unit consists of a pendulum supported in a rigid frame by low-friction bearings. The pivot arrangement includes an angular encoder to measure the angular position of the pendulum over its range of movement. The apparatus is fully enclosed with an interlocked guard covering all moving parts. Adjustable feet on the base of the unit enable accurate levelling of the equipment.

To perform a test, students raise the pendulum to the start position, where it is held by an electromagnet. They then clamp a specimen in a holder, which safely slots into the base of the frame at the lowest point of the pendulum swing. The separate instrumentation unit controls the release of the pendulum and measures and displays its angular position before and after the impact. The unit also directly displays energy absorbed by the impact in Joules. The equipment is designed to fracture plain carbon steel, brass, copper or aluminium specimens. Lengths of each of these materials are included, along with a hacksaw and cutting jig to enable cost-effective and convenient manufacture of test specimens. The cutting jig ensures repeatability of the notch position in each specimen and therefore valid comparisons of test results.

The equipment is supplied with a comprehensive user guide which includes equipment description and technical specification, installation and assembly, background theory, experiment procedures with results, and maintenance instructions.