Investigation at a top counter weight of a washing machine

During the development of a new washing machine a problem came up in spite of the durability of the newly designed top counter weight. The top counter weight is necessary to balance the drum of the machine. The problem was caused by the dynamical behavior of the system. A modal analysis was made at the compensation weight in the machine. Several different modes and eigenvalues were detected. The disturbing mode was found. It was caused by the stiffness of the fastening and the mass of the weight. The top counter weight was fastened in the axial direction of the drum. The disturbing mode was eliminated due to the change of fastening from axial to radial fastening. The problem is now solved. Another point of view are the other eigenvalues of the weight. The size of the weight looks like a xylophone bar and, in the same manner, it can vibrate. These modes of the weight itself are not disturbing modes, because the excitation forces are too small in this area and at this frequency range for exciting the compensation weight.