Impact testing is used to measure the toughness of materials, particularly plastics and metals, as well as the toughness of coatings that may be applied to these substances. Other samples include composites, glasses, concrete, and other construction and manufacturing materials. Toughness in this context is a specific property of various materials and is defined based on the amount of energy a material sample can absorb without breaking. Some materials may be strong, in that they can support a large load, but still brittle—they may break under a rapid application of force and energy. It is just this property that impact testing is designed to quantify, as the energy is delivered very rapidly.

There are two primary methods for impact testing: drop weight and pendulum. In the former, a weight is dropped on the sample. Adjusting the mass and initial height of the weight regulates the total energy delivered to the sample. In a pendulum system, a weight mounted on a pendulum is raised and allowed to swing down and strike the sample, which usually has been prepared by inscribing a notch in it, to serve as a point of concentration for the stress, and also to model the failure of the material in a reproducible fashion. Similar to drop-weight impact testing, the mass and height of the pendulum affect the delivery of the impact, and high-energy systems can use motivators to increase the energy of impact.

Simpler impact-testing systems provide pass/fail analysis depending on whether the sample breaks or ruptures or not. More complex systems have high-speed sensors that can track the loss of energy during the impact and provide more information about how the material deforms and ultimately fails. Two standard impact test methods, Izod and Charpy, use the pendulum method. These two tests have existed for more than a century but have been subsumed by modern standard methods based on them.

While the specific materials used in these tests are commonly metals and plastics, the actual end-users come from industries that are testing parts made of these materials. Everything from automobile bumpers to aircraft components is subject to impact testing. Other end-user markets include medical devices, paints and coatings, and the raw material suppliers of metals, alloys, plastic resins and finished plastics.

Although the test methods are standardized, there are many ways to differentiate products. The simplest differentiator is the maximum energy; table-top systems offer relatively modest limits, while large floor-mounted systems can shatter extremely tough materials. Other differentiators include temperature control, safety shielding, and sensors and software.

Most suppliers of physical-testing equipment compete in this market, as do some instrument firms that specialize in plastics analysis. In addition to the top vendors, suppliers include Tinius Olsen, BYK Instruments (Altana), Imatek, Jinan Testing Equipment, Mitutoyo and Qualitest.

Impact Testing at a Glance:

Leading Suppliers:

MTS Systems

Instron (Illinois Tool Works)

Zwick Roell

Largest Markets:

Aerospace

Automotive

Plastics

Instrument Cost:

$4,000-$70,000