英文原文.wps

1、英文原文 英文原文Experimental analysis of a composite automotive suspension armM. PINFOLDand G. CALVERT“(University of Warwick/'Rover Group Gaydon, UK)Received 11 November 1992;revised26 March 1993In applications where weigh

2、t saving and parts integration can be achieved, the Rover Grouphas been investigating the design and manufacture of components from composite materials. Themethods used in the different steps in the design-to-manufacture

3、 cycle in the high volumeautomotive industry are relatively well known for a steel component, but are not so wellestablished for a composite component. A design methodology for composites has been emergingin wh

4、ich a principal procedure is design analysis. One of the most established methods ofanalysisis that using the finite element technique, and this is being supplemented withexperimental tests on prototypes using

5、 photoelastic analysis and stress pattern analysis by thermalemission, coupled with conventional strain gauge monitoring. Little work has been undertaken tocorrelate the results obtained from these different test methods

6、 and to compare the results withmeasurements made on an actual component. This paper presents some of the work undertakenconcerning the analysis and testing of a composite automotive suspension arm. The resultsobtained f

7、rom the three different analysis techniques are compared with experimental test results,and their accuracy is discussed.Key w o r d s : autmotive suspension arm; stress analysis; finite element method; photoelasticanalys

8、is; SPA TE; strain gauges; sheet moulding compoundSol and de Wilde~state that 'composite materials have been used increasingly as structuralmaterials. A reason for t h i s . . , is that composite materials have high

9、strength to weight and highstiffness to weight ratios which can significantly reduce the weight of a structure... Perhaps themost important feature ofcomposite materials is that their mechanical p~:operties can be “tailo

10、red“to meet a specific criterion'. However, Johnson et al? suggest that 'composite design, analysis andfabrication technology must undergo major developments and successful demonstrations beforesignificant struct

11、ural components will be incorporated in production automobiles andtrucks'.Composite materials have to compete with steel within the engineering environment. Withinthe automotive industry this requires a certain amoun

12、t of technology transfer from places such asthe Advanced Technology Centre at the University of Warwick, which work with materialmanufacturers and automotive engineers to enable understanding about these materials as

13、an alter-native to the traditional materials such as steel. If composites are to compete with traditionalmaterials in a real sense, then automotive designers need to be fully aware of their strengths andcompound. Therefo

14、re, fiat plates, beams and discs constructed from SMC were analysed undervarious loading conditions before progressing on to the designed component.Most validation tests were carried out using straingauged specimens to c

15、orrelate with thefinite element analysis results. Although it is recognized that SMC is not an isotropie material dueto some fibre orientation during processing, for the purposes of analysis the material was assumedto be

16、 isotropic. Also, when the actual SMC suspension arm was cut up and examined, significantfibre distribution was observed in the ribs. It is felt that the correlation between the experimentaland analysis results validated

17、 this assumption in the case of thisparticular component.Strain gauge testsBefore undertaking the experimental test work, the composite component was mounted viaits rubber mounting bushes onto a relatively infinitely sti

18、ff structure. It is very difficult to cover allof the loading conditions when conducting experimental tests and thus a worst-case scenario isusually assumed. The worst-case loading condition on suspension components is k

19、nown as 'pot-hole brake'. This attempts to simulate the vehicle falling into a deep pot-hole at 30 mph with thebrakes fully applied at the point of impact. The resultant fore/aft and lateral loads are thencalcula

20、ted based on the weight and velocity of the vehicle. Due to the limitations o f the test rigthe full pot-hole loads could not be applied to the component, and thus reduced loads with thesame resultant direction as the po

21、t-hole loads were applied and the results scaled. The loadsapplied for the full pot-hole brake case were 24.2 kN in 'X' and 8.2 kN in “Y', and for the reducedload case were 5.9 kN in 'X' and 2.02 kN i

22、n 'Y' - - see Fig. 1.The strain gauges used consisted of six three-axis rosette gauges and 13 single-grid gauges,with 2.5 mm grid lengths, chosen to fit into the radii of the component in an attempt to measurethe

23、 maximum strain, Gauges were situated near the ball joint housing, where the loads wereapplied, and around the radii of the body mounting bushes, where the component would bemounted to the car subframe. Additional strain

24、 gauges were situated on some of the strengtheningribs and close to the anti-roll bar mounting position.SPA TE analysisStress pattern analysis by thermal emission (SPATE) can be used to determine the surfacestresses of c

25、omponents by studying the small changes in temperature due to cyclic loadingconditions. SPATE equipment comprises a detector unit with scanning head, an analogue signalprocessing unit and a digital electronic data unit.

26、The system works by detecting the minutetemperature changes which occur when a structure is cyclically loaded. The infra-red detectorscans the structure and correlates the measured output with a reference signal from the

27、 loadingsystem. An electronic data processing system correlates the detected stress-induced thermalfluctuations with the loading reference signal. A colour contour map of the sum of the principalstresses (cr~+ 4 ) is