Numerical Approach to Simulate Automotive Heater Hose Slip-Off Using Statistical Analysis

An automotive heater hose is a nylon-reinforced rubber component which has pressurized coolant flows from engine to Heating, Ventilation Air Conditioning (HVAC) unit and connected at either end using spring or worm clamps. One of the important design failure modes to study is the coolant leakage during hose slip-off scenario that can lead to walk-home failures. Overall dimensional variations, assembly loads and part variations can lead to such scenarios which are crucial to investigate using statistical approach for the robust design. To establish this, an experimental setup was conducted, and an equivalent CAE model was developed using Abaqus Standard. The Finite Element model comprised of an engine union pipe, a rubber heater hose and a spring clamp on the engine side of the vehicle. A suitable hyperelastic model for nylon-reinforced rubber and friction values were used to correctly represent the behavior of heater hose with adjoining steel components. The hose slip-off force between hose and union pipe were monitored which would indicate if the designed clamp force was able to hold it on to the union pipe. The effect of temperature was also studied on hose slip off force. The internal fluid pressure is neglected for the study as to simulate the lab condition. A factorial design of experiment study was conducted to determine the sensitivity of the important design factors. The response surface generated from the regression model with 95% confidence level indicated that union pipe bead diameter, friction between hose and the union pipe were critical parameters. The Response Optimizer model thus developed from these critical parameters enables to reduce the computation time and quick decision making in minimizing the hose slip-off. The established method can also be used on similar hose pull out conditions in other areas of the automobile.