Fastener Modeling for Joining Composite Parts

Transcription

1 AM-VPD Fastener Modelng for Jonng Composte Parts Alexander Rutman, Assocate Techncal Fellow, Sprt AeroSystems Chrs Boshers, Stress ngneer, Sprt AeroSystems John Parady, Prncpal Applcaton ngneer, MSC.Software Larry Pearce, Senor Lead Applcaton ngneer, MSC.Software

2 References Fastener Modelng for Jonng Composte Parts, Alexander Rutman, Chrs Boshers (Sprt AeroSystems), Larry Pearce, John Parady (MSC.Software Corporaton), To Be Presented at the 009 Amercas Vrtual Product Development Conference, Aprl -, 009, Phoenx, AZ Fastener Modelng for Jonng Parts Modeled by Shell and Sold lements, Alexander Rutman, Chrs Boshers (Sprt AeroSystems), Larry Pearce, John Parady (MSC.Software Corporaton), 007 Amercas Vrtual Product Development Conference, October -, 007, Detrot, MI Fastener Modelng for MSC.Nastran Fnte lement Analyss, Alexander Rutman, Adran Vsoreanu (Boeng), John Parady (MSC.Software Corporaton), 000 World Avaton Conference, October 0-, 000, AIAA

3 Objectve Develop an FM representaton of a fastener nstalled through multple metal and composte plates. Accurately represent fastener behavor Rapd model preparaton of each fastener Can be used wth parts modeled by shell elements wth sotropc or orthotropc materal propertes, parts modeled by sold elements wth sotropc propertes, or any combnaton of these parts Accounts for the effects of varable bearng stffness of a fastener - composte plate nterface

4 Representaton of a Fastener Jont Idealzaton of a plate-fastener system ncludes the followng: lastc bearng stffness of a plate and fastener at the contact surface Bendng and shear stffness of a fastener shank Compatblty of dsplacements of a fastener and connected plates n the jont

5 Compatblty of Jont Dsplacements Modelng dsplacement assumptons No nterference of the plates under load The plate s md-planes reman parallel to each other under load Planes under the fastener head and nut reman parallel to the plate mdplanes under load

6 xamples of Fastener Jont Models RBAR RB DOF,5,6 5,6,4,5,6 DOF,3,5,6

7 Interacton Between Fastener Shank and Joned Plates Bearng stffness between fastener shank and plate s represented by CBUSH element ach CBUSH element contans two non-zero axal and two non-zero rotatonal sprngs Translatonal and rotatonal bearng stffnesses are defned n PBUSH cards Sold lement Shell lement Sold lement CBUSH lements st plate nd plate 3 rd plate x

8 Stffness of a Fastened Jont n a Metallc Plate Combned plate and fastener translatonal bearng stffness Combned plate and fastener rotatonal bearng stffness S S xbr xbt S S ybr ybt t ν + ν 3 t p + cf cf t p t p t p 3 t p 4 d f Fastener st plate nd plate 3 rd plate 4 th plate cf t p - comp. modulus of plate materal - comp. modulus of fastener materal - thckness of the plate

9 Stffness of a Fastened Jont Change from Prevous Formulaton Comparson of Fnte lement and Analytcal Results for Translatonal Bearng Stffness Analyss Method Fnte lement Analyss t t ν Translatonal Bearng Stffness, lb/n S Δ analytcal S S FM,9,87 -,030, FM,55, %

10 Stffness of a Fastened Jont n a Composte Plate - xtenson Combned plate and fastener translatonal bearng stffness Where, S xbt t n n t S ybt + + Q cf Q cf Q ν 4 ( Q + Q66 ) m n Q n 4 ( Q + Q ) m n Q m Q + 4 Q m + Q + 4 Q n + 66 ν Q ν ν Q ν m cosθ n snθ ν ( Q ) 66 G ν ν ν ν cf Q Q - compresson modulus of fastener materal - transformed reduced stffness for ply n the x-drecton - transformed reduced stffness for ply n the y-drecton

11 Stffness of a Fastened Jont n a Composte Plate - Rotaton Combned plate and fastener rotatonal bearng stffness Centrod Locaton ( ) ( ) + n cf x x x x xbr Q c z c z M S ) ( φ ( ) ( ) + n cf y y y y ybr Q c z c z M S ) ( φ xbt n cf x S Q z z c + ) ( ybt n cf y S Q z z c + ) (

12 Analyss Procedure and Lmtatons The bearng stffness n the jont depends on the drecton of the fastener reactons. Because these drectons are not known pror to runnng the model, an teratve procedure s requred to accurately determne fastener reactons. For composte plates wth varable n-plane stffnesses, the sprng analogy used n ths analyss does not take couplng between transverse dsplacements nto account. The error nduced by ths approxmaton s expected to be small and wll decrease wth each teraton.

13 Procedure for Analyss of a Fastened Jont Construct FM, Determne Intal Propertes Run FM Determne Fastener Reactons Magntude and Drecton Update Fastener Stffnesses Summarze Reactons No Intal Run? Yes Converged Compare Reactons to Prevous Run Not Converged

14 xample Composte Plate n Double Shear Desgn Confguraton Fnte lement Model 00 lb Fasteners FM Isovew FM Upper Plate Removed

15 xample Bearng Stffnesses as a Functon of Resultant Fastener Drecton 90 θ 0

16 xample Fastener Reactons After Intal Run Fastener ID Rx Ry θ lb

17 xample Fastener Reactons After nd Run Fastener ID Rx Ry θ lb

18 xample Fastener Reactons After Fnal Run Fastener ID Rx Ry θ lb

19 xample Summary of Analyss Results Fastener Load Convergence Change n Load (lb) 3 Fastener, P x Fastener 3, P y Fastener, P y Fastener 3, P x Run # 4

20 Patran Fastener Bulder MSC.Software s currently developng a PCL procedure consstng of two parts: The frst part shall quckly and easly create fasteners n Patran for models contanng plates wth composte and optonally metal materal propertes. The second part s needed for updatng bearng stffnesses n the composte plate-fastener nterface. An MSC.Nastran procedure for automatcally teratng the process s very desrable to ncrease the speed of the analyss. Patran Iteratve Analyss Panel Patran Fastener Bulder Panel

21 Conclusons The fastener modelng technque developed for sotropc materals has been extended to models contanng composte plates. The prevous formulae for computng bearng stffnesses for fasteners n a metal plate has been modfed to better account for plate behavor. Due to the varaton of n-plane stffnesses of a composte materal, an teratve procedure s necessary to accurately determne fastener loads. An automated PCL procedure s under development to quckly and easly create fastener representatons n MSC Patran.

22 Contact Detals : For further nformaton please contact Alexander Rutman alexander.rutman@sprtaero.com Chrs Boshers chrs.boshers@sprtaero.com Sprt AeroSystems P.O. Box Mal Zone K78-0 Wchta KS, 6730 USA John Parady , ext. 5 john.parady@mscsoftware.com Larry Pearce larry.pearce@mscsoftware.com MSC.Software MacArthur Place Santa Ana, CA 9707 USA 3/05/009