?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F439%2F&rft.title=Resonant+whirling+of+two-piece+propshafts+in+rear-wheel-drive+cars&rft.creator=Gates%2C+D.&rft.subject=Materials&rft.description=Many+modern+cars+with+rear-wheel+drives+have+a+two-piece%2C+rather+than+the+traditional+one-piece%2C+props+haft+(or+tail-shaft).+The+two-piece+shaft+requires+less+floor+clearance%2C+and+hence+a+smaller+floor+tunnel%2C+and+does+not+suffer+from+the+high-speed+twisting+resonances+to+which+the+one-piece+shaft+is+susceptible.%0D%0A%0D%0AThe+two-piece+shaft+is%2C+however%2C+susceptible+to+a+lower+speed%2C+high+load+(high+torque)+phenomenon+in+which+the+propshaft+whirls+with+increasing+amplitude+until+its+restraining+rubber+bush+is+fully+compressed+in+its+mounting+bracket%2C+causing+a+thump+sound.+The+whirling+amplitude+builds+up+periodically%2C+so+that+a+regular+series+of+thumps+is+heard+at+a+frequency+of+about+5+per+second.%0D%0A%0D%0AThe+effect+is+very+sensitive+to+the+properties+of+the+rubber+bush+and+to+its+temperature.+Different+designs+of+bush+are+used+by+different+makers%2C+each+with+the+purpose+of+minimizing+both+the+whirling+problem+and+the+transmission+of+other+vibrations+to+the+car+body.+%0D%0A%0D%0AGMH+has+a+particular+design+which+it+would+prefer+not+to+vary%2C+because+of+retooling+costs.+It+can+however+vary+the+properties+of+the+rubber+material+itself.+By+trial+and+error+it+has+achieved+rubber+properties+which+control+the+whirling+problem+to+an+acceptable+level+under+normal+conditions.+GMH+posed+the+question%2C+to+the+MISG%2C+of+whether+one+can+give+theoretical+guidelines+for+optimal+rubber+properties.+This+might+lead+to+improved+control+of+the+whirling+problem.+It+would+also+be+useful+for+new+and+modified+propshafts%2C+if+it+could+replace+the+tedious+trial+and+error+process+previously+employed.%0D%0A%0D%0AGMH+were+also+anxious+to+gain+a+better+understanding+of+the+whirling+phenomenon%2C+and+felt%2C+with+us%2C+that+a+mathematical+description+of+the+phenomenon+was+a+prerequisite+for+the+study+of+the+rubber+properties.+The+thumping+phenomenon+is+observed+at+both+40+and+80+kph+approximately%2C+although+the+phenomenon+had+a+different+quality+at+these+two+speeds.&rft.date=1989&rft.type=Study+Group+Report&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F439%2F1%2FResonant-whirling-of-two-piece-propshafts-in-rear-wheel-drive-cars.pdf&rft.identifier=++Gates%2C+D.++(1989)+Resonant+whirling+of+two-piece+propshafts+in+rear-wheel-drive+cars.++%5BStudy+Group+Report%5D+++++