The invention provides a waveform-variable automatic
impact device for a
modal test, and belongs to the field of
modal tests. The waveform-variable automatic
impact device for the
modal test mainly comprises a controller, a digital steering engine, a
workbench, a
crank-connecting rod mechanism formed by a
crank disc and a connecting rod, an
impact head device, a sensor, a connecting stud, a linear
optical axis guide rail, lubricating components of various motion pairs, corresponding supporting and fixing components and the like, wherein the impact head device comprises an
impact hammer cap for damping replacement and a hammer body. According to the invention, the instantaneous rotating speed of the intelligent steering engine is controlled through
programming, specific impact waveforms such as triangular
waves, pulse
waves and the like are outputted, circumferential motions are transformed into reciprocating rectilinear motions by adopting a
crank-guide rod mechanism, and the
tail end of a guide rod is additionally provided with a hammer to output an exciting force. The
contact time between the hammer and an excited portion can also be controlled, and the adjustability of an impact force and the
impact time are ensured. A problem that manual knock contact is difficult in excitation
time control, poor in
repeatability and difficult to excite ideal pulse
waves is solved.