Study On Tire Dynamic Force During Impact Process

Wheel dynamic load is the main boundary input of automotive body and chassisstructure optimization design. When the car driving on rough roads, impact force effecttire. Ground impact force transferred to the axle through tire carcass elastic filtering andgeometric filtering. Existing envelope tire model of uneven road use equivalent way shapeas input, which require pretreatment in advance based on the known simulation path.Mainly of them is single point contact. Other tire models based on structural, such as finiteelement method can achieve many contact point with the ground. Therefore, establishing amore precise envelope model and describing the impact of contact between the tire and theground process is the key of dynamic wheel load simulation.This paper focus on investigate the contact of tire and road about wheel contact forceduring impact. The exploration focus on achieve the establishment of longitudinalenvelope wheel models. Mainly includes following three aspects. Firstly, explore thephysical collision model to describe tire impact and contact process. Secondly, discretecarcass. Finally, we research multi-point touch detection algorithm, which can determinethe location and direction tread contact force.1. Research physical colliding contact model. Combined with Investigation, thispaper will explore the physical contact model introduced to solve the tread force,comparative recovery coefficient, analytic method and finite element method. Coefficientof restitution law consider contact process to be instantaneous and the impact contact forceis infinite, only describer the speed of speed of before and after the contact. Analyticmethod use contact surface stiffness between two objects to calculate impact contact force.Finite element method will divide the two contact surface into grid and node, detectingthose nodes and grid contact situation, plus all contact force. FEM is a mature method ofcurrent research collision contact, but difficult to real-time computing large problems.Based on this analytical，this paper intends to adopt analytical method to calculate the impact of the tread contact force.2. The contact point detection algorithm. Contact process involves another importantresearch question is to determine the direction of the contact force and contact position.This paper put forward ray probe to detect contact situation. This method emission rays atthe center of the wheel and determine the location of the contact point with the roadthrough the intersection of computing rays. Achieve multi-point contact in tire model andaccurately calculate tire footprint.3. Establish multi-Imprinted block flexible carcass tire model. This paper focuses onthe tire longitudinal envelope, thus discrete carcass into mass elements in circumferentialdirection. Establish carcass quality unit dynamic model. Between the carcass quality unitis the spring and damping to describe carcass internal shear effect. Using gas pressurechanges in the description of the elastic filtering effect of the carcass. Each contact groundcarcass quality unit calculates longitudinal surface friction with the ground based on staticand dynamic friction model. When the imprinting block has relative sliding velocity,calculating longitudinal friction force of imprinted block based on friction model, whereroad surface friction coefficient depending on imprinted slip velocity impact. WhenImprinted with the ground is static, Imprinted block longitudinal ground forces isdetermined by the active force. Integrated grounding Imprinted longitudinal force andradial force to express of the wheel axle loads. Eventually, establish carcass radialdynamics and real-time calculation of flexible carcass deformation, thus we can expressthe tire envelope property on rough road. Contact force direction is determined by contactpoint of road. Simulating ground contact force of the tire tread rolling over typical unevenroad and a single point of contact model were compared with the longitudinal envelopetire to verify our built model has envelope property.