Hinge-Test

Das ist Deutsch:

The force on the hinge bolts will become more weak and loose gradually after a long term, repeated open-closing movement.
The Hinge is the part where controls the panel can be moved (opened and closed) and remained at a specific angle.
Therefore, the reverse angle and torque force of the hinges are our concerning on that what is the change of reverse angle and torque force and any deformation and crack after long-term movement.