The former causes forced vibration at the circular frequency of the crank shaft and the latter causes transient vibration at the natural frequency of the press. 慣性力激發的振動是以曲軸轉速為頻率的強迫振動，加工力激發的是以壓機固有頻率為頻率的過渡振動。
In the regenerative liquid propellant gun,the coupling oscillation of the fluid sys-tem in the reservoir including free vibration and forced vibration may be formed. 在再生式液體發射葯火炮中，貯液室流體系統可能發生由自激振動與強迫振動構成的耦合振蕩，在噴射結束期很可能形成共振。
