Axial-torsional interactions and wire deformation in 19-wire spiral strand

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1、AXIAL-TORSIONALINTERACTIONSANDWIREDEFORMATIONIN19-WIRESPIRALSTRANDw.s.UnINGDepartmentofMechanical,MarineandProductionEngineering,LiverpoolPolytechnic.FIMechE.N.JONESDepartmentofMechanicalEngineering,UniversityofLiverpool.FIMechE.Tensiletestswereperformedonastraightsteelstrandofthreelayer(12/6/1

2、)construction,havingacorewirediameterof3.66mmand3.33mmdiameterhelicalwires,underconditionsoffullend-fixity,partialrestraint,andendsfreefromtorsionalrestraint.Thetorquegeneratedundertensileloadwasrecordedaswellasthestrandextensionandrotationovera600mmgaugelength.Wiretensionsandbendingmomentsinth

3、eouterlayerofhelicalwiresweredeterminedatthemid-strandpositionfromtheoutputsofstraingaugesingroupsofthreewithparallelgridsandmountedparalleltothewireaxisonthecrownofeachwire.Therateofstrandextensionundertensileloadwasfoundtobegreaterintestswithreducedtorsionalrestraint,thegreatestrateoccurringi

4、nthefree-endtest.Thestrandrotationratewasalsofoundtobegreatestinthefree-endtest.Thegreatestdifferencefromthetheoreticallypredictedratesoccurredinafree-endtestwithincreasingload;predict-edvaluesofextensionandrotationunderestimatedthetestresultsby12and23percent,respectively.Displacementoftheload-

5、torqueplotsoccurredinthedirectionofreducingtorqueastestingproceeded.Thisappearstoindicatetheredistributionofthestrandloadbetweenthelayersofwires.Wiretensionsshowedamoreevensharingofloadinthefixed-endconditionthaninthefree-endcondition.Theincreaseinrateoftensionwithstrandloadwaslessformostwiresi

6、ntestswithreducedtorsionalrestraint,withthelowesttensionratesdevelopinginthefree-endcondition.Formostwires,therateofbendingmomentchangewithstrandloadwasgreater(inthesensetendingtodecreasetensilestressonwirecrowns)intestswithreducedtorsionalrestraint.However,thebendingmomentratesvariedgreatlybet

7、weenwires,thevariationbeinggreaterintestswithreducedtorsionalrestraintthaninfixed-endtests.1INTRODUCTIONGBendingmomentcomponentaboutbinormalTheauthorshaverecentlyreportedonastudyintotheaxisofhelicalwireresponseofwireropestrandofse