1、原文二Contact analysis for drum brakes and disk brakes using ADINAC.Hohmann*,K.Schiffner,K.Oerter,H.ReeseInstitute of Engineering Mechanics and Control Engineering, University of Siegen, Paul-Bonatz Str.911,Fachbereich 11, Mashinentechnik,57076,Siegen,Germany AbstractBrakes in cars and trucks are safet
2、y parts.Requirements not only in performance but also in comfort,serviceability and working lifetime are high and rising.Optimal design of todays brake systems is found using additional calculations based on finite element methods.For both types of brake systems,drum brakes and disk brakes,the diffe
3、rent parts of brakes,i.e.the brake pad with the friction material,the counter body and calliper,can be modelled.Two examples are given in this paper:a drum brake of a trailer and a typical disk brake used in passenger cars.The main problem to be solved is the calculation of the distribution of conta
4、ct forces between brake pad and counter body(drum or disk).The contact problem includes friction and is solved using the ADINA 7.1 sparse solver.After the brake pressure is applied,the turning moment on the axle rises constantly until the drum or disk respectively changes from sticking to sliding co
5、ndition.It is shown that the sparse solver is highly effcient for this sophisticated nonlinear problem.Results include deformation,stress distribution,contact pressure and showing which regions of the contact area are in sticking or sliding condition.#1999 Elsevier Science Ltd.All rights reserved.1.
6、Introduction1.1.Brake constructionBrakes in cars are expected to work properly with a minimum amount of service.The purpose of brakes is to reduce the velocity or to maintain it when the vehicle is driving downhill.Without brakes it would notbe possible to control the speed of the vehicle.Neverthele
7、ss the design of brakes is generally underestimated.In brakes high amounts of energy are transformed during short periods.This is underlined by the fact,that often the braking power is several times higher than the power of the engine. In cars and trucks different types of braking systems are used.I
8、n this paper only wheel brakes based on friction are considered.Generally two design forms are used:disk and drum brakes.The demands made by the vehicle industry are strict.The requirements will also rise with future development of lighter and more economical cars.This supports the need for efficien
9、t methods of calculating brake systems.The fnite element method is an ideal tool for this purpose.It is suited for analysis of both stress and temperature.In this paper the contact problem is described for disk brakes and drum brakes.For example a drum brake used in trucks and a disk brake used in s
10、mall passenger cars are presented.In order to transfer the kinetic energy of the vehicle into heat,friction brakes are commonly used at each wheel of the vehicle.The area of contact is the origin of the heat sources.Cooling surfaces emit heat into the environment.Nevertheless the temperatures can ge
11、t as high as 9008C(16508F) at the contact area. For proper operation the following criteria have to be considered:l high and stable coeffcient of friction;l good thermal capacity;l good wear resistance of the tribo system(brake linings and disk respectively drum);l mechanical resistance of material;
12、l weight optimized construction;l and use of environmental suited materials.Despite different geometric design (see Fig.1), both types of brakes use the same principle to create the braking force: fixed brake shoes are pressed against a rotating counter body. Due to friction the brake force is actin
13、g contrary to the motion of the counter body there by reducing its velocity.The resulting friction force is proportional to the normal force N and the coeffcient of friction m.The brake parameter is defned as the relation between friction forces and the applied force and is used in the comparison of
14、 different brake designs.A typical brake used in cars consists of the operating device(pedal or hand lever),the transfer unit and the wheel brake(Fig.2).For disk and drum brakes the normal force N is applied,using mechanical,pneumatic or hydraulic transfer units.A servo unit raises the force applied
15、 by the driver: (1)The factor is the total transmission ratio of the brake.The friction force = acts on the rubbing surface.The distance between the friction force and the centre of revolution is the effective radius .The origin of the friction force for disk brakes is approximately the middle of th
16、e friction surface,depending on the shape of the friction area.In the case of drum brakes the effective radius is the inner radius of the drum.Effcient software and hardware is needed for the simulation of complete brake systems.ADINA Version 7.1 simplifes the construction of the complex three-dimensional structures together with providing reliable algorithms for the solution of the contact problem.Usi
