7.8.3. Portable Dynamic Test Units The limited volume of thermal vacuum chambers led to the creation of test units which have a smaller size, which in turn imposes certain requirements on their principal scheme. Tn order to substantially reduce the size of test units to reproduce the motion of the equivalent mass, flywheels and mechanisms to convert rotary motion into forward motion are used. The moment of inertia of the flywheel is determined from the equality of kinetic energies of the motion of the equivalent mass m3 and the rotation of the flywheel, and is calculated from the formula where is the pitch of the screw, and is the transmission ratio of the reducer. These test units are usually used to reproduce central impact (for “rod and cone” docking devices) or varieties thereof (for APDAs). Thus, the equivalent mass is equal to the mass on central impact . To reproduce impact with a velocity the flywheel is whirled to an angular velocity To connect the flywheel, which is initially accelerated by an electrical engine to a given velocity, to the slave element there is a control coupling. The momentum of the coupling is calculated from the condition of creating the maximum possible force of impact, that is, . Tn testing the velocity of rotation of the flywheel is recorded, as well as the parameters of the docking mechanism (deformation of the shock absorber and its derivatives), and the force of impact is evaluated from the acceleration of the flywheel or using the force sensors. The portable test units with a flywheel to test the APDA (Figure 7.17) makes it possible to reproduce the following cases of interaction: 1) central impact; 2) impact with roll; 3) impact of the two rings. Moreover, the stand can test the
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