Impact Hammers Information
Impact hammers are used in structural and modal analysis to determine component or system response to impacts of varying amplitude and duration. It is simply a hammer with a force transducer in its head is paired with an accelerometer on the component being tested to compare impact and response. Impact hammers are used for modal and structural behavior analysis for all types of components and systems. The most critical specifications for impact hammers are the force and pulse duration, both rated by minimums and maximums. Force is measured in pounds, kg, N and other similar units. The pulse duration, a measurement of the time the hammer is imparting a force on the object being tested, is a very short span of time, often measured in milliseconds. Another important specification is the upper limit of the frequency range. This is the highest frequency for which the response will be tested, and can be altered by using accessory tips, if available.
Impact hammers can be controlled either manually or remotely. That is, the device could resemble an actual hand-held hammer and is used by manually striking an object. Remote operation impact hammers are either more like an automated piece of machinery that the operator tells how much force to apply or else a handheld power tool that is operated by actuating a switch.
A range of striking tips of various materials and hardness is often available, allowing for different forces and response times. In general, harder tips will deform less than softer tips during impact and will therefore have a shorter pulse duration. Typically the hardest tips are used to measure response at the highest frequencies. Additional masses that attach to the back of the hammer head are another common accessory. These are used to increase excitation force beyond the force of the plain hammer.
Some impact hammers come as a kit that can include the hammer, an accelerometer to be mounted to the object being tested, signal conditioners for the transducer signals, and a multichannel analyzer for the hammer and accelerometer. A kit like this would be everything an engineer needs to do analysis using impact hammers.