Date of Award
Doctor of Philosophy
Industrial and Manufacturing Engineering
Dr. Mitchel J. Keil
Dr. Steven E. Butt
Dr. Tarun Gupta
Dr. Azim Houshyar
This research investigates a brake hose simulation model that includes the effect of nonlinear torsional stiffness in addition to the usually considered bending stiffness on brake hose shape. A simulation model consisting of beams and torsion springs is presented in this research to predict brake hose shape when it is twisted through different angles. This knowledge can help reduce the possibility of a significant source of failure related to brake hose abrasion on nearby structures, thus eliminating the safety hazard of a premature failure of hoses. This would also eliminate the need for polymer bumpers at the rub points since an appropriate length that does not rub against rigid components can be found. The bumpers cause high stress in the hose during the vehicle operation, and thus pose a safety hazard. The ability to model flexible components also leads to a reduction in ergonomical issues due to the accurate prediction of hand clearance for assembly. The United States Council of Automotive Research Digital Virtual Tools Task Force calculated a present value cost savings of $5.78M from the development of a virtual tool for designing brake hoses.
A fixture was fabricated to hold hoses of different lengths firmly after initiating a specific twist at one end. A digitizer was used to obtain scanned point cloud data of hose shapes between coplanar and non-coplanar attachment points for different lengths of hoses. These non-contact means of taking measurements were essential in reducing errors in data collection. The torque values for various angular deformations were adjusted in order to define the torsional stiffness curve for all torsion springs in the model so that the predicted hose shape would lie near the center of the point cloud data for every 10° of twist, from 0°-180° for 11", 13", and 16" brake hoses held between coplanar attachment points. A cubic torsional stiffness curve was obtained from a regression analysis of the three torsional stiffness curves for 11", 13", and 16" hoses.
The method for measuring deviations between brake hose samples and the simulation model using digitizer post-processing software is presented for the first time. The average deviation of the torsion spring model for a hose length typically used in midsize cars and SUVs when twisted to the maximum angle possible in these vehicles was 2.803mm. A one-sample t-test of average deviations for ten samples of 10" and 13" hoses showed that the population mean of average deviations is less than 5.15mm (hose radius) at a significance level of 0.05. The method to construct the simulation model and data analysis to determine its accuracy can be used for other flexible components such as robot dresses and cable harnesses.
Thomas, Jai, "Experimentally Reducing Preset and Hysteresis Effects in Creating a Non-Linear Model for Brake Hoses" (2010). Dissertations. 631.