Abstract: When helical springs, especially stranded-wire helical springs are impacted, the movement of every spring coil will be very complicated owing to various factors, such as the mass, inertia, resonance of springs, the elastic deformation of steel material and the internal friction induced by the relative slipping among different steel wires of stranded-wire helical springs. Based on that, a set of motion models of various helical springs under vibrational condition are proposed and they can be used to measure the relationships between displacement and time, velocity and time, acceleration and time for every spring coil. The experimental results show that the motion models of helical springs, combining a non-contact and multi-channel testing unit developed by correlative project team, are successfully in revealing the rules about how the motion of spring coils changes with the time going, which can offer experimental basis for the dynamic design theory of helical springs.

Key words: Detection, Helical springs, Motion model, Spring coils