Multi-plate Wet Disc Brake Fluid-solid Coupling Analysis

Multi-plate wet disc brake with its own characteristic of simple structure, thestrong heat of recession and difficult to be polluted, etc. Recently, wet brake hasbeen more widely used. Prone to friction linings of the friction loss, partially due tohigh temperature burning, or due to the dual role of stress causes cracks warped steeland other undesirable phenomena, seriously affecting the overall performance ofbrake and the safety of the vehicle.In response to these problems, Chongqing DajiangXinda Vehicle Company proposed the produce-learn-research “project of thefluid-structure interaction analysis which is based on Multi-plate wet disc brake”,proposed the friction model of Multi-plate wet disc brake which is based on fractaltheory, Establish a system of fluid-structure coupling equations, and research themechanism of fluid-structure coupling; use finite element analysis method toresearch the flow rate, pressure of brake fluid field, the stress, strain, safety factor ofstructure field, the stress, strain, safety factor of coupling field, etc; research theregular of how the brake performance parameters impact on the characteristics offluid-structure. The main contents of this paper include the following aspects:(1)In order to study the braking process of contacting state between the dual steeland friction plates (friction linings and friction chips collectively), establish amulti-plate wet disc brake friction model which is based on fractal theory, andanalyze friction between the real and nominal asperity contact area, fractal dimension,contour amplitude scale factor influence of the friction coefficient of adhesion andfriction calculated molecular friction between the contact surfaces asperity tangentialforce and its elastic-plastic zone normal load, to determine the elastic and plasticcontact area of the critical contact spot area, get the basic variation of coefficient offriction and friction;(2)Establish a multi-plate wet disc brake structure model, make certain simplified,and boundary conditions determined by calculating brake condition, the brake pressure.To import the simplified friction model into ANSYS, simulating and analyzing the fluidfield and structural field. To research characteristics of the flow field velocity, fluidpressure on the friction contact pressure and structural fields, such as stress, safetyfactor;(3)Import the result of fluid analysis into structural analysis model, building a multi-plate wet disc brake fluid-structure coupling model to study the fluid-structurecoupling characteristics which is different from the results of structure simulation, andcompare with the true state of the brake braking, shows that the results of characteristicsof fluid-structure coupling is closer than the analysis and the real brake situation;(4)Analyze the regular of how the friction coefficient, brake pressure, brake speed,material properties of dual steel and friction plate impact on brake performances, andoptimization analysis the brake performance parameters, select the parameters which isbetter to the overall performance of brake when it is braking;(5)Simulate and analyze the parameters which is be optimized and use disc brakebench test to simulate the process of brake’s actual braking, by way of collecting,comparing and theoretical calculation to get the results of experimental, to verifycorrectness of the friction model which is based on fractal theory and the rationality ofoptimized parameters.