JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 40

FEATURE
… …

“Aeronautics”
Experimental validation
Two experiments were performed to validate the ABAQUS finiteelement model of the variable-stiffness cylinder. A modal test was first performed and then modal frequencies, mode shapes and physical responses were compared. The analytically-predicted and experimental modal frequencies matched within 5% up to a frequency of 1000 Hz. The modal response simulations also showed good agreement with the experimental results both for the location and the amplitude of the response. The second experiment was a bending test. The set-up resembled a

g / Fibre-placed, variable stiffness composite: the future of aerospace structures? of the cylinder through rigid end plates. Therefore, the distribution of the axial load depended on the distribution of the axial stiffness. The load distributions of the baseline and the variable-stiffness cylinder are shown in Figure 2(b). The circumferential stiffness variation resulted in a redistribution of the axial loads on the variable-stiffness cylinder, such that the tension side was more effective in carrying loads (region A), the compressive loads were carried by a larger part of the cylinder (region B) and the peak at θ = 180° was significantly reduced (region C). The compressive side of the cylinder was critical for buckling, so redistributing the compressive loads over a larger portion of the cylinder and reducing the compressive peak load permitted a higher bending moment to be carried before buckling occurred.

Manufacturing
The variable-stiffness and the baseline cylinder were manufactured using an Ingersoll fibre placement machine at the developmental centre of the Boeing Company in Seattle, Figure 3a. The 7 degrees of freedom of the machine allowed the placement of curved fibre courses, while the machine’s tow cutting and restarting capabilities were used to maintain a constant ply thickness. A variable-stiffness ply is shown in Figure 3b.

Fig. 4: Bending test setup

4-point bending set-up: the cylinder was mounted in the area where there was no shear force, such that the cylinder was subjected to pure bending, Figure 4. A 3.5 MN MTS test bench was used to load the test fixture in tension, causing a bending moment such that the upper side of the cylinder was in tension and the lower side was in compression. Displacements and rotations were measured using LVDTs, while strains were measured using strain gauges and a digital image correlation system. The experimental results of the baseline cylinder were used to calibrate the boundary conditions in the finite-element model, which was then used to predict the response of the variablestiffness cylinder. Geometric nonlinearities, the test mechanism and geometric imperfections were also included in the finiteelement model, which affected the value of the predicted buckling moments. The variable-stiffness cylinder showed an improvement

a

More information
The Aerospace Engineering faculty of the TU Delft is one of the largest of the eight faculties at TU Delft and one of the largest faculties devoted entirely to aerospace engineering in northern Europe. Collaborations with numerous international and multinational industries through research groups abroad as well as in the Netherlands ensure that the Faculty remains at the forefront of the latest developments in the aerospace industry. Website: http://lr.home.tudelft.nl/en

b
Fig. 3: Advanced fibre placement of a variable-stiffness composite cylinder (a) Fibre placement of the cylinder (b) One of the variable-stiffness plies

40

jec composites magazine / No58 June - July 2010


http://lr.home.tudelft.nl/en

JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010

Cover
Editorial
Market Place
Advertisers
Index
Contents
NEWS WORLDWIDE
- Companies
- Innovations
- Agenda of events
BUSINESS
- Market survey
- Trends
- Human Capital
FEATURE - AERONAUTICS
- Market
- Nano
- Simulation
- Fibre placement
- Assembling
- Thermoplastics
USERS' PLATFORM
- Composites in the world
- Successful Partners
- Civil Engineering
KNOW-HOW
- Reinforcement
- RTM
- Induction
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - Cover
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 2
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - Editorial
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - Market Place
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - Index
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - Contents
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 7
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Companies
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 9
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 10
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Innovations
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Agenda of events
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - BUSINESS
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Market survey
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 15
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 16
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 17
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Trends
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 19
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Human Capital
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - FEATURE - AERONAUTICS
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Market
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 23
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 24
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 25
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 26
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 27
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Nano
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 29
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Simulation
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 31
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 32
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 33
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 34
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 35
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 36
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 37
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Fibre placement
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 39
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 40
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 41
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Assembling
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 43
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 44
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Thermoplastics
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 46
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 47
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 48
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 49
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 50
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - USERS' PLATFORM
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Composites in the world
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Successful Partners
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Civil Engineering
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 55
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 56
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - KNOW-HOW
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Reinforcement
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 59
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - RTM
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 61
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - - Induction
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 63
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 64
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 65
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 66
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 67
JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 68
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