EXPERIMENTAL RESEARCH OF DYNAMIC PARAMETERS OF STRANDED-WIRE HELICAL SPRINGS UNDER IMPACT LOAD

摘要

When stranded-wire helical springs are impacted, the movement of every spring coil will become very complicated owing to various factors, such as the mass, inertia and resonance of spring, the internal friction of steel wires, also the relative slipping during different steel wires of stranded-wire helical springs. Base on that, a non-contact and multi-channel detection device of dynamic parameters of stranded-wire helical springs is proposed, which involves the design of mechanical structure, the lectotype and installation of sensors, the hardware and software module of signal acquisition and analysis. This device, combining a novel algorithmic of data processing special for springs, can be used to measure the relationships between displacement and time, velocity and time, acceleration and time for every spring coil. The results show that when stranded-wire helical springs are impacted, all spring coils will vibrate, also this movement will transmit to the fixed end in the form of longitudinal wave and reflect there; the relationship between displacement and axial length of spring coils point is non-linear, the same situation for the relation between velocity and spring coils' position; additionally, in the beginning of impact there is a large deformation in the active end, whereas on the contrary, little deformation in the fixed end while on the other hand there is a large deformation in the fixed end when the wave reaches there and reflects. Therefore, in practical design work of stranded-wire helical springs, it is necessary to analyze the impact response of springs in order to avoid the phenomenon of excessive deformation of some spring coils by selecting reasonable parameters.