Experiments on modal coupling in self-excited vibration of a wiper-blade

Experimental results are presented for self-excited vibration of an automotive wiper. The self-excited vibration is generated by a stick-slip motion. It is of practical importance to suppress the self-excited vibration of the wiper. To find out modal coupling in the vibration of the wiper, simplified wiper is constructed. Movement of simplified wiper is separated into horizontal and vertical directions to simulate a motion of the actual wiper. The simplified wiper and the actual wiper are used for experiments. Static deformation of a wiper blade is measured. The blade is pressed on a glass surface. The wiper blade shows characteristics of soft-hardening spring involving a buckled deformation. Modal coupling in the self excited vibration is examined by sweeping the wiper on a rotating glass table with constant angular velocity. Increasing a load pressed on the blade, coupling vibration is generated due to self excitations along glass surface and parametric movements in vertical direction. The vibration amplitude is suppressed extremely when the load is close to the buckling load. Moreover, the maximum Lyapnov exponent of the dynamic response shows least number of the modes contributed to the self excited vibration.