Dishwasher Noise Reduction

Performing a frequency study on a dishwasher to reduce noise

Consumers demand quiet appliances. To dampen the sound levels created by the pumps, fans, and water impacting the internal walls, dishwashers use insulation like mastic, bitumen, and other special trim pieces.

Using these materials requires expensive manufacturing processes. Developing a modeling strategy to assess dishwasher sound levels helps create a quieter design while also reducing costs.

Operational Experiments

First, operational experiments were conducted on both dishwasher models. Each dishwasher model was structurally modified by removing the sound dampening materials to understand the subtle differences in operation and common noise sources. The results of these experiments provided valuable information for the remaining project tasks.

After these experiments, SIMCenter conducted bench experiments on individual dishwasher components. The experiments used a modal impulse hammer to excite the component, and then the structural and acoustic responses were recorded by accelerometers and microphones. These results generated data that was used to recommend improvements for future components.

Natural Frequency Study

The CAD models of the dishwashers were modified, then researchers constructed a structural and coupled acoustic-structure finite element model using ABAQUS. The model was correlated to the experimental structural frequency response functions on the dishwasher models. Dishwasher components were also modeled.

Modeling the internal dynamics of motors and pumps is incredibly complex, so SIMCenter instead focused on developing a force representation profile for use as an excitation for structure-borne noise and vibration. Physical component experiments were designed, constructed, conducted, and modeled to extract this force profile.

Once all of the data from the experiments and simulations were considered, SIMCenter made recommendations to improve noise, vibration and harshness (NVH).