OPTIMIZATION OF COMPOSITE TUBES FOR A THERMAL OPTICAL LENS HOUSING DESIGN

OPTIMIZATION OF COMPOSITE TUBES FOR A THERMAL OPTICAL LENS HOUSING DESIGN A Thesis by HECTOR CAMERINO GARCIA GONZALEZ Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2003 Major Subject: Aerospace Engineering OPTIMIZATION OF COMPOSITE TUBES FOR A THERMAL OPTICAL LENS HOUSING DESIGN A Thesis by HECTOR CAMERINO GARCIA GONZALEZ Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Thomas C Pollock (Chair of Committee) Dimitris C Lagoudas (Member) Ozden O Ochoa (Member) Walter E Haisler (Head of Department) August 2003 Major Subject: Aerospace Engineering iii ABSTRACT Optimization of Composite Tubes for a Thermal Optical Lens Housing Design (August 2003) Hector Camerino Garcia Gonzalez, B.S., Instituto Politecnico Nacional Chair of Advisory Committee: Dr Thomas C Pollock This thesis describes the manufacturing, structural analysis and testing of a composite cylinder for space application This work includes the design and fabrication of a reusable multicomponent mandrel made of aluminum and steel and the manufacturing of a carbon fiber reinforced tube in an epoxy resin matrix This structure intends to serve as the optical lens housing onboard a spacecraft In addition, some future work needs to be done before this component is certified The objective is to determine if the composite meets the stiffness and strength requirements for lens housing The structural analysis is made by means of a finite element model simulating the true boundary conditions and applied loads The testing includes the design of a fixture to allow the composite cylinder to be mounted in one of the testing machines at the Department of Aerospace Engineering at Texas A&M University and the preparation for the actual test The response to the experimental analysis will be compared to the numerical simulation (Finite Element Model) to verify the results iv To my parents and my sister v TABLE OF CONTENTS CHAPTER I INTRODUCTION A Overview B Objectives C Literature review Bending stiffness closed-form solution a Smear property approach b Laminated plate approach c Effective bending stiffness II Page 2 12 FINITE ELEMENT ANALYSIS 14 A FE model Element selection a Laminate element properties b Orthotropic material formulation Model generation a Geometry and mesh creation b Boundary and loading conditions Convergence study B Results [0/90]4 carbon-epoxy tubes a Stresses through the thickness for the specimen b Strains through the thickness for the specimen [0/90]3 carbon epoxy tube a Stresses through the thickness for the specimen b Strains through the thickness for the specimen [0/90]2 carbon epoxy tube a Stresses through the thickness for the specimen [0/90]4 [0/90]4 [0/90]3 [0/90]3 [0/90]2 14 14 15 16 16 18 25 27 28 31 31 35 35 36 36 36 40 vi CHAPTER Page b Strains through the thickness for the [0/90]2 specimen [0/90/45/-45]s carbon epoxy tube a Stresses through the thickness for the [0/90/45/− 45]s specimen b Strains through the thickness for the [0/90/45/− 45]s specimen III 41 42 42 42 EXPERIMENTAL PROCEDURE 45 A Mold manufacturing Overview of manufacturing processes a Rolling b Pultrusion c Filament winding Mold fabrication B Test articles manufacturing Materials Manufacturing process Tube trimming C Specimen testing Test article and fixture design Testing procedure a Load application b Data acquisition c Experiment performing Aluminum specimen IV 45 45 45 45 46 46 47 48 50 60 63 65 67 67 68 68 69 RESULTS 71 A Experimental results Midspan deflections Noise filtering Statistical analysis of [0/90]4 specimens B Analytical results C Discussion 71 71 73 79 84 85 V CONCLUSIONS 90 VI RECOMMENDATIONS 92 vii CHAPTER Page REFERENCES 93 APPENDIX A 96 APPENDIX B 115 APPENDIX C 126 APPENDIX D 128 VITA 131 viii LIST OF TABLES TABLE Page I AS4 carbon fiber mechanical properties 19 II Physical properties of epoxy, Gougeon West 105/206 21 III Carbon/Epoxy mechanical properties, as calculated using equations 2.2, 2.3 and 2.4 21 IV 6061-T6 Aluminum mechanical properties, www.matweb.com 24 V Convergence study 29 VI Maximum values of stress ply by ply [0/90]4 specimen 31 VII Maximum values of strain ply by ply [0/90]4 specimen 35 VIII Maximum values of stress ply by ply [0/90]3 specimen 38 IX Maximum values of strain ply by ply [0/90]3 specimen 40 X Maximum values of stress ply by ply [0/90]2 specimen 40 XI Maximum values of strain ply by ply [0/90]2 specimen 41 XII Maximum values of stress ply by ply [0/90/45/ − 45]s specimen 42 XIII Maximum values of strain ply by ply [0/90/45/ − 45]s specimen 44 XIV Materials for manufacturing of the carbon/epoxy tubes 49 XV Bidirectional woven carbon graphite, www.aircraftspruce.com 50 XVI Shrink tape characteristics 58 XVII Tube dimensions 65 XVIII Specific stiffness from experimental results 73 XIX Stiffness intervals for the t-student distribution 82 ix TABLE Page XX Effective moduli from lamination theory 84 XXI Bending stiffness from closed form solution 85 XXII Comparison of midspan maximum deflection between experiment and finite element results 87 Comparison of effective bending stiffnesses from analytical solution including specific stiffnesses 88 XXIII XXIV The t distribution 129 x LIST OF FIGURES FIGURE Page Coaxial tubes Plate section of composite tube laminate FEMAP laminate element 17 FEMAP plane quadrilateral elements 17 Carbon/epoxy tube geometry 18 Carbon/epoxy cylinder meshed 22 Loading ring mesh 23 Cylinder and end caps activated 23 End cap mesh 24 10 Composite tube refined mesh 25 11 The desired boundary conditions above, were obtained by doubling the length of the tube, applying the load to the center, and allowing rotation at both ends 26 12 Experimental fixture 26 13 Boundary conditions 27 14 Loading ring and end caps define the boundary conditions in FEA model 28 15 Test article and fixture dimensions 29 16 Final mesh 30 17 [0/90]4 uy (Ty ) translation 32 18 Maximum stress σx ply [0/90]4 33