Simulated Effect of Fiber Mesh Wrap Angle on Composite Pressure Hose Behavior. David Nelson MSC.Software

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1 Simulated Effect of Fiber Mesh Wrap Angle on Composite Pressure Hose Behavior David Nelson MSC.Software

2 Overview and Objective Fibre reinforced hoses are a common component in automotive, aerospace and industrial system designs. Analysis accuracy of systems that contains these hoses depend on the accuracy of the representation of the hoses. The composite hose braid layer, included as reinforcement, is the stiffest layer in the hose, and is the principal structural element In order to predict the overall hose behaviour, an accurate portrayal of the braid layer is essential. Commonly these hoses are supplier designed items and the material properties for each layer are not readily available. The objective of this study was to identify the important parameters of the fiber layer of a composite pressure hose CAE model and subsequently improve accuracy in response to pressure, lateral, and axial loading conditions as compared to basic experimental results.

3 Data What is known, what isn t At the start of this study, some hose data was available, although there were unknowns associated with this data. Known with High Confidence: Hose layer definitions thickness and materials Braid layer general construction woven cloth, single layer. Hose dimensions and shape Details of other components within the assembly. Hose response in testing to pressure, lateral and axial loading Known with some uncertainty: Material characteristics of hose layers from physical testing Braid layer 0, 45, 90 coupon tests from deconstructed hoses. Approximate braid layer angular alignment Unknowns: Braid warp/weft uniaxial properties Braid Layer 2D orthogonal properties Braid layer orientation Relative to hose axis Warp to weft angle Sensitivity to orientation angle assumptions. The study will try to determine the unknowns through iterative CAE analysis using PATRAN and NASTRAN.

4 Composite Hose FEM The lateral displacement analysis is described below. This non-linear model is run in NASTRAN v Solution 400. All component interfaces are via glued contact (FEM detail is proprietary) 5 DOF constraint Y displacement = 20 mm 6 DOF constraint

Unknown: Braid Layer Uni-axial properties

test coupons and some of the assumptions

one direction of braid fibers represents

5 Unknown: Braid Layer Uni-axial properties The following illustration depicts the test coupons and some of the assumptions for deriving the uni-axial braid fiber properties Braid Fibers 0 not aligned with fibers 45 assumed to be aligned with one direction of braid fibers represents uni-axial fiber properties. 90 not aligned with fibers

6 Unknown: Braid Layer 2D Orthogonal properties The braided layer consists of a laminate of two layers of the uni-axial material. Uni-axial properties Uni-axial properties The braided layer laminate properties are one layer in the finite element model to simulate the composite hose.

between the two uni-axial directions ( assumed initially to be ±50

7 Unknown: Braid Orientation vs. Hose Axis The first round of study assumes a fixed braid angle between the two uni-axial directions ( assumed initially to be ±50 ) and investigates the effects of varying the orientation angle for the braid layer. The images below illustrate how the fiber orientations were varied for this study 50º Braid Warp- Weft angle 0º 50º Xº 0º Braid Orientation vs. Hose Axis

8 Lateral Force (N) Axial Force (N) Unknown: Braid Orientation vs. Hose Axis For the ±50 Braid properties, the original 0 (aligned with hose axis) results show the best correlation with the experimental results (data withheld). Lateral Force vs Lateral Deflection Axial Force vs Lateral Deflection Lateral Deflection (mm) 0Deg 2Deg 5Deg 20Deg 30Deg 40Deg 50Deg 60Deg 0Deg 2Deg 5Deg 20Deg 30Deg 40Deg 50Deg 60Deg 70Deg Deg Lateral Deflection (mm) Therefore, braid orientation is 0 (aligned with hose axis)

9 Unknown: Braid Orientation vs. Hose Axis For the ±50 Braid properties, with 0 orientation, the pressure results indicate some unexpected behavior. The diameter growth is larger than expected and the hose length is reduced with increasing pressure inspection of the 2D orthotropic properties of this braid laminate indicates a high value for n 12. Experimental Original Diameter = 24.0 mm Measured Diameter under pressure = 24.5 mm Growth = 2.08% FEA Original Diameter = mm Deformed Diameter = mm Growth = 6.88% Internal Pressure P D p D 0

10 Conclusions: Braid Orientation vs. Hose Axis Conclusions for varying the braid orientation relative to the hose axis: The lateral load and axial load vs. deflection response varies greatly with the orientation angle (up to a factor of 8X for 0 vs. 50 degrees) The best results were zero degrees from the hose axis. Diameter growth in response to pressurization remains unrealistic. Second round of study - Braid warp to weft angle Assumes braid orientation of 0 degrees and investigates varying the braid warp-weft angle Definition: Warp-weft angle is the angle between the two uni-axial directions for warp and weft.

11 Unknown: Braid Angle warp to weft angle The images below illustrate how the fiber orientations were varied for the second round of study. 50º Braid Warp- Weft angle 0º vs. 50º 55º 55º

12 Unknown: Braid Layer 2D Orthogonal properties Define the lay-up of the uni-axial properties at a selected braid angle to create the 2 layer laminate properties of the braid Extract the composite material properties for the 2 layer laminate using the PATRAN application

13 n12 E11 E22 G12 Unknown: Braid Angle Warp vs. Weft The plots show how the E11, E22, G12 and n12 values for the braid laminate trend with varying braid angle. E11 E22 G Braid Angle Braid Angle Braid Angle n Braid Angle

14 Unknown: Braid Angle Warp vs. Weft Effects of Varying Braid Angle on Correlation - Pressurization Model D 0 D P Delta % Experimental % +-50 Deg Braid Angle % +-55 Deg Braid Angle % Deg Braid Angle % Deg Braid Angle % +-60 Deg Braid Angle %

15 Lateral Force (N) Axial Force (N) Unknown: Braid Angle Warp vs. Weft Lateral Force vs Lateral Deflection Axial Force vs Lateral Deflection Deg Braid Angle +-55 Deg Braid Angle +_60 Deg Braid Angle +-50 Deg Braid Angle +-55 Deg Braid Angle +-60 Deg Braid Angle Lateral Deflection (mm) Lateral Deflection (mm) Lateral and axial force response is insensitive to braid warp-weft angle.

16 Conclusions: Braid Angle Warp vs. Weft Studying the effect of braid angle variation within a small range showed large variations in some of the laminate 2D properties The Poisson s ratio for the braid laminate appeared to have the most significant effect on the pressurization results, allowing a choice that produces close correlation with the physical response. While varying the braid angle, the lateral force and axial force results remained stable.

17 Conclusions A reasonable approximation of the uniaxial and laminate orthogonal properties for the braid layer can be derived from simple and imperfect coupon test data. Estimates for the braid layer angles can be a good starting point for material property correlation, but the effect of varying these angles can have a substantial effect on the prediction accuracy. The first study confirms the braid orientation relative to the hose axis. Any orientation misalignment led to much higher lateral and axial forces in response to lateral displacement.

18 Conclusions (cont d) A combination of: a simple, but realistic idealization with an FEA thoughtful interpretation of available material test data basic bench test correlation can lead to a very satisfactory representation of a component that is paramount to predicting system performance, yet difficult to characterize.

FINITE ELEMENT ANALYSIS OF COMPOSITE MATERIALS

FINITE ELEMENT ANALYSIS OF COMPOSITE MATERIALS Ever J. Barbero Department of Mechanical and Aerospace Engineering West Virginia University USA CRC Press Taylor &.Francis Group Boca Raton London New York