Useful measurements of mode shapes on very light structures require excitation from a very low mass exciter with a high resonance frequency (300 kHz). These outstanding features are available with the Endevco 2301 mini modal hammer. The hammer structure features very high stiffness and low head mass (only 2 grams). The ergonomically designed grip provides optimal hammer control thus reducing the possibilities of “double hits”.

The sensitivity is 100 mV/lbf (22.7 N). Some applications include disc drive read heads, turbine blades and many other lightweight structures.
The fixed impact tip is manufactured from case hardened 17-4 stainless steel. Frequency response can be controlled by using layers of tape in the impact area, or by the supplied extender mass.

The hammer features an Isotron impedance converter providing an IEPE output which is compatible with most FFT analyzers and data acquisition systems. Endevco’s 4416B single channel signal conditioner or the model 133 three channel conditioner are recommended for use with this hammer series. To excite larger structures, see the 2302 general purpose modal hammer and the series of sledge hammers.

Features

• Ultra-lightweight (2 grams)
• Ergonomically designed grip
• Low impedance (Isotron®) output

Accessories

• P/N EHM 1669 Head Extender
• P/N 34248 Storage Container

Model 2302
Modal hammer

Scaled modal models require a precise force measurement. This can be achieved by electrodynamic and servohydraulic exciters controlled by a signal generator via a power amplifier. A more convenient and economical excitation method is a hammer fitted with a high-quality piezoelectric force transducer. In applications where a high crest factor and a limited ability to shape the input force spectrum is of no concern, impact hammer
testing is an ideal source of excitation. Impact hammers are highly portable for field work and provide no unwanted mass loading to the structure under test.

The modal hammer excites the structure with a constant force over a frequency range of interest. Three interchangeable tips are provided which determine the width of the input pulse and thus the bandwidth. Typical force spectra produced with different tips are shown on the right.

For larger structures, an optional head extender is available to increase the head’s mass. The hammer structure is acceleration compensated to avoid glitches in the spectrum due to hammer structure resonances. The ergonomically designed handle grip helps the user optimize control and reduce the possibility of “double hits”. The hammer features an Isotron impedance converter providing an IEPE output which is compatible with most FFT analyzers and data acquisition systems.

Features

• Model 2302 -5, -10, -50, -100
• Four ranges
• 3 replaceable tips
• Low impedance (Isotron®) output
• Acceleration compensated
• Ergonomically designed grip

Model 2303 / 2304 / 2305
Modal sledge hammers

Endevco’s instrumented sledge hammers provide a convenient and economical means of exciting large structures. The one and three pound hammers are designed for exciting such structures as machinery, shafts, large beams, pipelines, storage tanks and other large structures.
The 12-pound hammer can be used on larger structures including bridges, buildings, decks and floors.

The modal hammer excites the structure with a constant force over a frequency range of interest. Four interchangeable tips are provided which determine the width of the input pulse and thus the bandwidth. Typical force spectra produced with different tips are shown on the right.

Each hammer is constructed with a hardwood handle and a cast iron head. The electrical cable is routed internally and terminates to a BNC connector on the end of the handle.

The hammer features an Isotron® impedance converter providing an IEPE output which is compatible with most FFT analyzers and data acquisition systems.

Features

• Rugged construction
• Four interchangeable faces
• IEPE (Isotron®)
• 1, 3, and 12 pound heads