JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 43

FEATURE “Marine” Development of operational monitoring sensors for the Veolia racing monohull The use of composite materials has been significantly improving racing sailboats performances for more than fifteen years. Hulls, masts and appendages are now made of carbon prepreg materials that consist of Nomex honeycomb and often high-modulus fibres to reduce the weight and increase structural strength and stiffness. too close because of incorrect design stiffness and an insufficient number of ±45° plies used with respect to the keel length. Those plies are needed to give the keel stiffness in torsion. After reinforcement, strain gauges were bonded to the keel to measure its twist/bend deformations during sailing. An example of a result for fifteen seconds of recording is shown below (Fig.1). ROLAND JOURDAIN, SKIPPER OF THE VEOLIA IMOCA MONOHULLL PASCAL CASARI, ASSISTANT PROFESSOR, UNIVERSITY OF NANTES, FRANCE number of problems have been observed in conjunction with the improvement of sailboat performance, notably keel instability at high speed and the poor resistance of core material to slamming. This article reports on three series of measurements carried out during sailing to: • analyse the keel’s dynamic behaviour in order to make the boats more reliable, • monitor rudder lift in real time in order to adjust the rudder blade’s relative angle of attack, • quantify the strain rate of the sandwich core for a more accurate characterization of the materials. The keel’s dynamic behaviour A number of racing sailboats have a carbon keel spar. The choice of carbon saves considerably on weight, but gives rise to vibration resonance linked to the coupling of the hydrodynamic forces and the keel’s twist/bend deformations. When the boat sails at high speed for the first time, the bulb end of the keel starts to yaw violently. This phenomenon is called “flutter” in the aviation sector. Here, it is due to the coupling of the keel’s fundamental twist and bend modes of vibration Veolia IMOCA Monohull when the two modes are Fig. 1: Twist/bend deformations during sailing The first curve corresponds to bending strain, which occurs mainly when the boat sails through a swell. This gives a highly variable curve. The ratio shown is the bending deformation ratio between values recorded during sailing and those obtained during a regulatory test that consists in heeling the keel to one side at a 40° angle while the boat is motionless, making the boat at a maximum 10° angle. The second curve shows the twist deformation caused by bending load. The yawing caused by the sailboat’s trajectory makes the keel vibrate at its fundamental twist mode. A frequency of about 5 Hz appears each time the boat yaws significantly, and is rapidly damped. JEC Composites Magazine / No35 September 2007

JEC COMPOSITES MAGAZINE - Issue #35 - September 2007

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #35 - September 2007

Edito
CONTENTS
NEWS WORLDWIDE
- Companies
- Agenda of events
- 2008 JEC Singapore
BUSINESS
- Market survey
- Niche markets
- Trends
- Human capital
FEATURE - MARINE
- Market
- Raw Materials
- Process
- Application
USERS’ PLATFORM
- Composites in the world
- Successful partners
- Applications
KNOW-HOW
- Warp knitting technology
- Testing
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 1
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 2
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - Edito
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 4
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 5
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - CONTENTS
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 7
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Companies
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 9
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Agenda of events
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 11
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - 2008 JEC Singapore
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 13
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 14
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 15
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Market survey
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 17
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 18
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 19
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 20
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 21
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 22
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 23
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Niche markets
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 25
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Trends
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 27
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 28
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 29
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Human capital
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 31
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Market
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 33
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Raw Materials
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 35
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 36
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 37
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 38
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 39
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Process
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 41
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 42
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 43
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 44
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 45
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 46
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 47
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Application
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 49
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Composites in the world
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Successful partners
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 52
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 53
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 54
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 55
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 56
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 57
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Warp knitting technology
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 59
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 60
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 61
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 62
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - - Testing
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 64
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 65
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 66
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 67
JEC COMPOSITES MAGAZINE - Issue #35 - September 2007 - 68
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