Design of racing yachts for durability IFREMER ONR workshop Nantes, August 24th 2012 A. Miller, R. Balze, H. Devaux, S. Guého 1
High-tech composite and boats design and engineering for 15 years TEAM 8 engineers and draftmen Brest KNOW-HOW Static, vibrations, buckling Analytic and numerical solutions Custom and one design COMPOSITE SKILLS Highly anisotropic carbon composites High and very high modulus carbon Monolithic and sandwich design Composites parts assembly MEANS FEM : FEMAP/NASTRAN, COSMOSWORKS, ADINA S, ADINA F, ADINA FSI CAD : SOLIDWORKS, TOPSOLID, AUTOCAD Dedicated in-house softwares RESEARCH AND DEVELOPMENT Fluid structures interaction Appendages instabilities Wave impact and slamming with IFREMER Bondings with IFREMER / ENSTA Bretagne Labeled Crédit Impôt Recherche 2
Innovative projects INDUSTRY Jules Verne 2012 holder Banque Populaire 5 (45 days around the world) VOR 2012 winner Groupama 4 IMOCA 60 rigging, hulls, keel structures SAILBOATS RACING Hydroptère : Holder of world records speed sailing America s Cup 2010 winner BMW Oracle s Platform and Wing America s Cup projects since 1987 Dynamic flight simulator for THALES 3
Race time (days) Durability and fast boat design : pushing the limits Offshore racing pushing the limits 1960 : Sir Chichester in 40 d 12h 30min 2004 : Michel Desjoyeaux in 08d 08h 29min 50 40 30 MULTICOQUE MONOCOQUE 20 10 0 1950 1960 1970 1980 1990 2000 2010 Winner race time for the OSTAR / The Transat Plymouth (UK) Newport (USA) 2012 : 40m trimaran Banque Populaire V breaks around the world record : 45 days! 4
Durability and fast boat design : high, complex and repeated loadings Severe sea loading Loads not easy to model non linear, dynamic, Hydro/structural coupling, Random and repeated Full speed deceleration load case Severe slamming Wave jump => Complex design, involving many phenomenons 5
General know-how for good fatigue life : core bonding, porosity, adequate SF, resin weight, etc... Durability and fast boat design : some aspects Some new issues that involved quite extensive developements from HDS in the past 10 years : 1. Keel flutter 2. Wave impacts 3. Weight gain bonded joints Areas of breakage due to harder wave impacts Main sail track Keel breakage due to flutter 6
1. Keel flutter : the phenomenon Known from airplane wing design Appeared on boat with keels fins getting thinner and thinner F lift Angle of attack Side displacement Airplane fin flutter Coupling between structure vibrations and hydro loads => Amplification can lead to breakage ORMA 60 keel breakage after flutter phenomenon 7
1. Keel flutter : HDS R&D HDS Analytical model FSI Numerical Simulation Tank testing with IFREMER (M. Le Boulluec) In house students works + PhD Thesis (R. Balze) with LTDS (Ecole Centrale Lyon) - Validation of model for flutter critical speed prediction - Study of driving parameters 8
1. Keel flutter : real life cases Sill : Observed critical speed ~ 19 Kts Calculated critical speed = 18.5 Kts Delta Dore : Observed critical speed ~ 22 Kts Calculated critical speed = 20.4 Kts => Work and models validated in real life 9
2. Wave impacts : soft crash on sandwich materials Sandwich materials stiff and light, but sensitive to impact damage Boats faster and faster through rough seas new wave impact damage, difficult to model Testing? - Standard methods use rigid impacters - different from water impact loading (different breakage modes) One of a series of trimaran beam breakage in Route du Rhum 2002 alternative testing with IFREMER Brest Typical hard impacter testing Partnership with IFREMER Brest (P. Davies, D. Choqueuse, B. Bigourdan) 10
Microstrain 2. Wave impacts : soft crash on sandwich materials Damage type changes with core type corresponds to witnessed damages on boats method relevant for that application Nomex honeycomb Aluminium honeycomb Study of significant parameters Study of strength to repeated impacts 10000 8000 Foam Repeated impact, Foam core, 2,8 kj 6000 4000 => Enough datas to modify design and solve the issue 2000 0 0 1 2 3 4 5 6 7 8 9 10 Impact number Repeated impact damage Partnership with IFREMER Brest (P. Davies, D. Choqueuse, B. Bigourdan) 11
2. Wave impacts : soft crash on sandwich materials Dynamic FE model with ADINA (IFREMER / B. Bigourdan) Partnership with IFREMER Brest (P. Davies, D. Choqueuse, B. Bigourdan) 12
3. Main sail track glueing : why? Car F sail Mast Track bolting detail Sail Track Groupama 4 Volvo Ocean Race 2012 Winner Track on mast to fit the sail Typical fixture : bolts every ~75mm Typic. 400-600 bolts + nut + reinforcement = significant weight Replace bolting with glue? 13
3. Main sail track glueing : testing Research on bonding joints with IFREMER 1 / ENSIETA 2 / UBO 3 Joints testing and improvement Glued tracks testing FEA models Track pulling test on an old mast FEA model of glued track 1 : P. Davies, 2 : J.Y. Cognard, 3 : R. Creac hcadec Removal of ~75% of the bolts Improved knowledge on optimized bonding details 14
Conclusions Sailboats design - More and more cutting edge science - New fields of investigation and developpement - HDS is one of the innovative actors HDS design America s Cup 67m rigid wing Fast evolutions : - New issues, new solutions - Boats = good «labs» - Developpements can be transferred to industrial projects 15