How do Impact Analysis work?
Impact tests apply a defined energy in a very short time, so the material responds in a brittle or semi-brittle manner that differs from slow tensile behaviour. Pendulum instruments release a weighted hammer from a fixed angle; the hammer strikes a supported or cantilevered specimen and the energy absorbed is calculated from the difference between release and follow-through angles, or measured directly by an encoder. Instrumented hammers add a strain-gauge striker that records force against time, so crack initiation and propagation energies can be separated. Drop weight and dart methods use a falling mass: a dart striking a clamped film gives the energy for 50% failure, while a tup striking a pipe section assesses resistance to external damage. Specimen geometry, notch radius, support span and conditioning temperature all control the result.
Which Impact Analysis variants are available?
- Izod Impact Tester for Plastics — An Izod impact tester breaks a notched specimen held as a vertical cantilever and reports the energy absorbed per unit of width.
- Charpy Impact Tester for Plastics — A Charpy impact tester strikes a horizontally supported notched or unnotched specimen in the middle and reports the energy absorbed.
- Instrumented Pendulum Impact Tester for Plastics — An instrumented pendulum impact tester fits a strain-gauged striker that records force against time during fracture, separating crack initiation from propagation.
- Falling Dart Impact Tester for Plastic Film — A falling dart impact tester drops a weighted dart onto a clamped plastic film and determines the energy that causes 50% of specimens to fail.
- Falling Weight Impact Tester for Thermoplastic Pipe — A falling weight impact tester drops a defined mass and striker onto a pipe or fitting specimen to assess resistance to external damage.
How do I choose the right variant?
Select the method named in your material or product specification, because results are not interchangeable between geometries. Izod suits rigid moulding materials and is common in resin specifications, while Charpy is preferred for plate, sheet and weld evaluation and is more widely used in Europe. Instrumented hammers are chosen when the failure mode itself must be studied rather than only the absorbed energy. Falling dart testing applies to films and thin sheets where a pendulum cannot hold the specimen, and falling weight testing applies to pipes, fittings and thick sections. For any of these, specify the energy range, specimen conditioning options, notch-cutting equipment and whether low-temperature conditioning is required.
Where are Impact Analysis used?
Impact Analysis are specified in impact strength qualification of moulding grades, notch sensitivity comparison between formulations, low-temperature toughness testing, impact resistance of plastic film and packaging, external damage resistance of thermoplastic pipe and verification of weld and plate toughness.
Which standards and certifications apply?
Work with Impact Analysis is commonly governed by ISO 179-1, ISO 180, ISO 6603-2, ISO 8256, ASTM D256, ASTM D6110, ASTM D1709, ASTM D2444 and IEC 61010-1. Instrument certifications such as CE marking are confirmed per configuration and never assumed.
What are the key considerations before purchase?
Cut specimens with the notch in the specified orientation, because anisotropy from moulding flow changes the result substantially; use a motorised notch cutter and verify the notch radius with a profile gauge. Condition specimens at 23 °C and 50% relative humidity, or in a bath at the test temperature when low-temperature toughness is measured, and transfer them to the machine quickly. Verify the pendulum by releasing it without a specimen, confirm that friction losses stay within the standard limit, and check the blade and supports for wear or damage. Report the specimen type, notch geometry, hammer energy and observed failure mode together with the numerical result.
