Experimental Evaluation and Consideration of Numerical Method of Zanchor CFRP Laminates

Transcription

1 Experimental Evaluation and Consideration of Numerical Method of Zanchor CFRP Laminates Yuichiro Aoki, Yosuke Nagao, Takashi Ishikawa Advanced Composite Technology Center, Japan Aerospace Exploration Agency Fumihito Takeda Nagoya Aerospace Systems Works, Mitsubishi Heavy Industries, LTD, Japan

2 Outline 1. Background, objectives 2. Overview of Zanchor technology - What is Zanchor technology? - Experimental findings of Zanchor CFRP laminates 3. Numerical simulation (FEM analysis) - Develop a novel numerical method to evaluate Zanchor CFRP laminates 4. Summary 2

3 Background Conventional CFRP laminates (2D-layup) In-plane direction Out-of-plane direction High High performance Strength Stiffness Poor interlaminar strength (= (= No No reinforcement) Strength (MPa) Ex.T800H/ Quasi-isotropic JAXA results Tens. Comp. OHC CAI Poor interlaminar strength affects CFRP strengths, especially CAI, OHC or peel strength of interface of skin/stringer structure. CAI strength OHC strength Peel strength 3

4 Interlaminar strength improvement Z-pinning 3D 3D fabric Stitching RTM or or RFI Novel Technology Zanchor Developed by Evaluated by 4

5 Objectives Experimental phase: Evaluate resin impregnation and mechanical properties of of Zanchor CFRP laminates. Analytical phase: Develop a numerical method to to evaluate Zanchor CFRP laminates. 5

6 Evaluation of Zanchor CFRP Material: CF(NCW)/Two parts epoxy resin Process: VaRTM Resin impregnation test 36ply, 54ply, 72ply, 99ply, ply-dropped laminate Mechanical property test Tension, Compression, OHC, CAI 6

7 Finite element analysis (Modeling) Interlaminar reinforcement and in-plane degradation are defined by a variation of material properties. ¾Zanchor density and location are defined by a function f(x,y). ¾The function is arbitrary, which can express Zanchor density. ¾ z Zanchor Location Density by an arbitrary f(x,y) Variation Variationof ofmaterial materialproperties properties Comptest2006, 10th-12th April 2006, Universidade do Porto y x Zanchor In-plane In-planedegradation degradation Out-of-plane Out-of-planereinforcement reinforcement 7

8 Finite element analysis (Modeling) Material definition by Field Variable. xπ yπ f ( x, y) = sin cos f ( x, y) 0. 9 p p Periodic function: z 0 Distribution of the field valuable (FV) in FE mesh E xx (GPa) y E yy (GPa) E zz (GPa) x General material part f ( x, y) < 0.9 Zanchor part Element: 3D solid FEM code: ABAQUS Ver. 6.5 xy = xz yz G zy = G xz (GPa) G yz (GPa) General part Zanchor part

9 Finite element analysis - Tension test 100 mm 90 0 (a) Z=1 (b) Z=2 (c) Z=4 25 mm Zanchor part Schematic view view of of Zanchor density for for tensile test test Elastic modulus (GPa) Comparison of of Elastic modulus against Zanchor density In-plane strain Zanchor density 9

10 Summary Mechanical properties of of Zanchor CFRP laminates were evaluated by by experiment and a numerical model was developed and applied to to tensile test. Experimental phase: Zanchor provides improvement of of resin impregnation. In-plane tensile and compressive strengths slightly decreased by by Zanchor itself. Interlaminar damage resistance and CAI strength were improved significantly. Analytical phase: Numerical model was developed and applied to totensile test. Results of of in-plane elastic property agree well with experimental one. 10

11 Future works DCB test simulation Progressive failure analysis Zanchor model + Cohesive zone model T w G c Initiation criterion w Initial crack: 20 mm 12.5 mm Propagation criterion 150 mm Zanchor Z-normal stress 11