3.Initiatorandpressurecartridgeproducehigh-pressure gassesinthecombustion chamberformedby thepiston,cylinderandhousing. 4.Adisplacement betweenthepistonandcylinderoccursasaresultofthehigh-pressure gasses. 5.Thedisplacement ofthecylinderpullsthelockingringoffthethreadedsegmentswhilethepiston pushesdownonthesegments.Withthethreadedsegmentsfreeofthelockingring,thesegments areforcedoutawayfromthestudundertheactionoftheradialloadproducedbythepreloadandthe downwardforceofthepiston. 6.Withthethreethreadedsegmentsfreefromthematingthreadsofthebolt,theboltwillbefreetoeject underthestrainenergyproducedfrompreloading. Itisthisinstantaneous releaseofboltstrain energythatproducesthegreatestcomponent ofshockoutput. SN9500 SeriesUltraLowShockSeparation Nut BasicDesi.qn Parameters Thebasicmechanism construction fortheSN9500 ULSisshowninFigure2.Thedesignparameters are asfollows: •ShockOutput: lessthan19,620m/s2(2000g) •Leakage: 1x10-4cc/second through theinternal seals •Release Mechanism: piston/cylinder •Actuation Time:lessthan10milliseconds •Initiation Device: NASAStandard Initiator, singleordualinitiators •PowerRequirements: 5ampere, 25voltspulsedpower •Mounting: flangemount •MatingFastener: boltorstud Theory ofOperation Thetheoryofoperation fortheSN9500 ULSisnearlyidentical tothatoftheSN9400 1.Application ofapreload totheseparation nutviaastudorboltproduces aradialloadbetween three threaded segments andthestud/bolt. 2.Thethreethreaded segments andtheradialloadarecontained byalocking ring,whichunlikethe SN9400 isnotfastened tothecylinder. Thethreethreaded segments aremounted overahardmounted keyedbase,whichridesonarotorcam.Thesekeysalongwiththerampsoftherotorcam lockthesegments andprevent rotation. 3.Initiator andpressure cartridge produce high-pressure gasses inthecombustion chamber formed by thepistonandcylinder. 4.Adisplacement between thepistonandcylinder occursasaresultofthehigh-pressure gasses. 5.Thedisplacement ofthecylinder pullsthreepinsfromtherampsoftherotorcamallowing therotor camtorotatedownthusrelieving thestrainenergyofthebolt/stud. 6.Withthepreload relieved acoiledspringejectsthelocking ringfromthethreaded segments. 7.Withthethreaded segments freeofthelocking ring,thesegments areforcedoutawayfromthestud undertheactionoftheradialloadandthedownward forceoftheseparator. 8.Withthethreethreaded segments freefromthematingthreads ofthebolt,theboltwillbefreetofall orbeextracted fromtheseparation nut. Separation NutShockOutput Threemainsources contribute toshockoutputduringseparation nutactuation, 1)Pyrotechnic Shock, 2) Release ofBoltStrainEnergy and3)Mechanical Impact ofinternal components. Thesethreesources occurasthreedistinct events during actuation oftheseparation nut.Thepyroshockoccurs at approximately 2-3milliseconds aftertheapplication ofcurrent totheinitiator. Thiseventconsists ofthe rapidexpansion ofpyrogasses thatdotheworkofactuating theinternal mechanism. Thesecond event, release ofboltstrainenergy occursat3-5milliseconds aftertheapplication ofcurrent. Thethirdevent, mechanical impactoftheinternal components consists ofthepiston/cylinder mechanism completing the strokeandimpacting ontheseparation nuthousing. Thiseventoccurs at5-7milliseconds afterthe application ofcurrent andmakesthelargestcontribution toshockoutputintheSN9500 ULS.TableIlists NASA/CP--2002-211506 132