AVALLE M.

GOGLIO L.

MAURI M.

English

AVALLE, MASSIMILIANO

GOGLIO, Luca

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

05 August 2020POLITECNICO DI TORINORepository ISTITUZIONALEComparison of different joining techniques in a crashworthiness perspective / AVALLE M.; GOGLIO L.; MAURI M.. -(2003). ((Intervento presentato al convegno European vehicle passive safety network.OriginalComparison of different joining techniques in a crashworthiness perspectivePublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/1412194 since:Publications Office of the European Union1Comparison of different joining techniques in a crashworthiness perspectiveMassimiliano Avalle – Politecnico di TorinoPierfranco Mauri – Henkel Loctite Italia2Contents Comparison of joining techniques Joining technique for car body construction Mechanical testing  Results and discussion Design of crash structures with different joining techniques Experimental results from crash boxes Redesign of crash box with adhesive bonding Comparison of the results3Why using alternative joining solutions? Adhesive bonding helps increasing stiffness During polymerisation other fixing system is needed Adhesive bad compatibility with spot-welds Adhesive and other mechanical fasteners can join different materials Repairing possible4Joints testing Spot-weld strength Static Fatigue Dynamic/Impact Loading conditions5KS2 specimen60°30°0°90°• Formerly used by Hahn et al. for fatigue• Material ZST340• Samples fromfor  6Testing systemDouble sliding  frameConnections with spherical jointsInclined grips (0°-90°)piezoelectric load-cells (during dynamic tests)Details of the 30° loading system7Testing apparatus• Drop-tower• Height 12 m, • Mass 60-120 kg • 300 kN max.• 13 m/s vmax• Equipped for impact testing (in compression)• Equipped with tensile test grip• Load measured with piezoelectric load-cells• Stroke measured with an optical encoder• Universal hydraulic material testing equipment DARTEC HA100• 100 kN max• 100 mm/s vmax• Load measured with a strain-gage load-cell• Stroke measured with LVDT8Spot-weldsExperimental results Load & stroke measurement Number of loading speed: 3 Low-speed: 0.01 mm/s Medium-speed: 80 mm/s High-speed (impact): 5.5×10³ mm/s Load-curve characteristic Failure surface is derived from maximum load as a function of the loading angle9Spot-weld results Low speed  0°  30°  60°  90° • Apparatus: DARTEC HA100• Loading speed: 0.01 mm/sStroke (mm)Load (kN)10Spot-weld results Medium speed  0°  30°  60°  90° • Apparatus: DARTEC HA100• Loading speed: 80 mm/s (=0.08 m/s)Stroke (mm)Load (kN)11Spot-weld results High speed  0°  30°  60°  90° • Apparatus: DARTEC HA100• Loading speed: 5.5 m/sStroke (mm)Load (kN)12Spot-weldsLow speed samples13Spot-weldsHigh speed samples14Analysis of the results Joint strength is analysed as a function of the loading angle: An elliptic limit curve is assumed: A different limit curve is obtained for each loading speed12max2max=+NNTT15Spot-weld strength vs. loading Limit curve as a function of the loading angle( )2maxmax2maxtan11cos NTTFαα +=Loading angle (deg)Maximum load (kN)16Spot-weld strength vs. loading components 12max2max=+NNTTMaximum tensile load (kN)Maximum shearing load (kN)17Failure surfacesStatic (0.01 mm/s) Dynamic (5 m/s)Peel (90°) Shear (0°) Peel (90°) Shear (0°)18Alternative joining systems for automotive constructions Riveting Self-riveting, punch riveting, Henrob joint Clinching Adhesive bondingpunch riveting Clinching19Clinching compared to spot-welds (1/2)Material: Mild Steel ( approx. 300 N/mm2)1. Round die, ∅ 5mm 2. Round die, ∅ 8mm,  3a. Rectangular die, w. 4mm, shear 90 °  3b.Rectangular die, w. 4mm, shear 0 ° 4. Spot Weld, Standard spec. minimum, ∅3 & 4mmCopyright© 2001 ATTEXOR Clinch Systems SA20Clinching compared to spot-welds (2/2)Mondino, I., Properzi, M., Giunti, T., Calderale, P.M., “La fatica di giunzioni meccaniche per strutture veicolistiche innovative” (Fatigue of mechanics joints for innovative car body structures) Proceedins XXVIII AIAS Conf., 199921KS2 specimen60°30°0° 90°• Formerly used by Hahnet al. for fatigue• Material DC04• Samples from22Clinching and BondingExperimental plan KS2 specimen loaded at different angles Clinched 21 samples Bonded LOCTITE Hysol® 9466 21 samples Clinched+bonded 22 samples Loading speed: quasi-static 0.01 mm/s Bonding procedure  Sanding (paper sand P80) Degreasing (LOCTITE® 7063) and bonding Polymerisation: 90 minutes @ 100°C23Clinched and bonded KS2 specimenClinched+bondedClinched24Clinched & clinched+bonded samplesClinched+bonded, 90°Clinched+bonded, 0°Clinched+bonded, 60°Clinched+bonded, 30°Clinched, 30° Clinched, 90°Clinched, 60°Clinched, 0°2500.20.40.60.811.21.40 0.5 1 1.5 2 2.5 3Stroke (mm)Load (kN)Clinching Test results  0°  30°  60°  90° • Apparatus: DARTEC HA100• Loading speed: 0.01 mm/s260246810120 2 4 6 8 10Stroke (mm)Load (kN)Bonding Test results• Apparatus: DARTEC HA100• Loading speed: 0.01 mm/s270246810120 1 2 3 4 5 6Stroke (mm)Load (kN)Clinching+bonding Test results• Apparatus: DARTEC HA100• Loading speed: 0.01 mm/s  0°  30°  60°  90° 280246810120 15 30 45 60 75 90Loading angle (deg)Maximum load (kN)ClinchedBondedClinched+bondedClinched and bonded joint strength vs. loading Limit curve vs. Loading angle( )2maxmax2maxtan11cos NTTFαα +=29Clinched and bonded joint strength vs. load components 0246810120 2 4 6 8 10 12Normal load (kN)Shear load (kN)ClinchedBondedClinched+bonded12max2max=+NNTT30Clinched and bonded joint energy vs. loading angle Failure energy vs. Loading angle01020304050600 15 30 45 60 75 90Loading angle (deg)Failure energy (J)ClinchedBondedClinched+bonded31Different joining solutions: conclusions Joining by clinching is effective and a good alternative to spot-weld The use of adhesive strongly increase strength and energy absorption capability Clinching can be use to make bonding operations easier: the pieces are kept in place up to complete polymerisation  Clinching in addiction to bonding offers additional safety as an extreme protection in the case of adhesive premature failure32Behaviour of crash boxes with alternative joining solutsions Is it possible to substitute spot-welds with other joining systems directly in the common constructive solutions? Crash behaviour can be improved?33• Cleaning and surface preparation with sand paper• Degreasing with Loctite 7063• Activation with Loctite 7388• Application of Loctite 330 adhesive• NDT ultrasonic inspectionBonded crash-box production60 60• Cleaning and surface preparation with sand paper• Chemical degrease• Mixing of components and application of CIBA araldite adhesive• NDT ultrasonic inspection34NDT procedure by Rossetto & Goglio(ref. XXIX AIAS et al.)Ultrasonic NDT inspection35Stress analysis of the bonded flanges15303060 15sp.1FF FF04080120160200-10 -8 -6 -4 -2 0coordinate y [mm]Von Mises equivalent stress  [MPa]adhesive layer thickness 0.2 mmadhesive layer thickness 0.4 mmPosition (mm)Equivalent stress (MPa)360510152025-10 -8 -6 -4 -2 0 2 4 6coordinate y [mm]Von Mises equivalent stress  [MPa]flat fillet fillinground fillet fillingImprovements by filletingPosition (mm)Equivalent stress (MPa)37Quasi-static crushingSpot-welded crash-box0510152025300 10 20 30 40 50 60 70 80 90 100spostamento [mm]Forza [kN]saldatura a punti - trave N4016003saldatura a punti - trave N4016002saldatura a punti - trave N40160010200400600800100012000 10 20 30 40 50 60 70 80 90 100spostamento [mm]Energia [J]saldatura a punti - trave N4016003saldatura a punti - trave N4016002saldatura a punti - trave N4016001Spot-welded - test 4016 03Spot-welded - test 4016 02Spo -welded - test 4016 01Energia(J)Stroke (mm)Load (kN)Stroke (mm)Spot-welded - test N4016003Spot-welded - test 4016002Spot-welded test 4016001380510152025303540450 10 20 30 40 50 60 70 80 90 100spostamento [mm]Forza [kN]adesivo LOCTITE 330 - trave B1adesivo LOCTITE 330 - trave B5adesivo LOCTITE 330 - trave B30200400600800100012000 10 20 30 40 50 60 70 80 90 100spostamento [mm]Energia [J]adesivo LOCTITE 330 - trave B1adesivo LOCTITE 330 - trave B5adesivo LOCTITE 330 - trave B3Quasi-static crushingAdhesively bonded crash-boxBonded LOCTITE 330 - test B1Bonded LOCTITE 330 - test B5Bonded LOCTITE 330 - test B3Energia(J)Stroke (mm)Load (kN)Stroke (mm)Bonded LOCTITE 330 - test B1Bonded LOCTITE 330 - test B5Bonded LOCTITE 330 - test B339Quasi-static crushingComparisons (1/2)0200400600800100012000 10 20 30 40 50 60 70 80 90 100spostamento [mm]Energia [J]saldatura a punti - trave N4016002adesivo LOCTITE 330 - trave B1adesivo CIBA araldite 2010 - trave B4Stroke (mm)Energy (J)0510152025300 10 20 30 40 50 60 70 80 90 100spostamento [mm]Forza [kN]saldatura a punti - trave N4016002adesivo LOCTITE 330 - trave B1adesivo CIBA araldite 2010 - trave B4Stroke (mm)Load (kN)Spot-welded - test N401Bonded - LOCTITE 330 – test B1Bonded - CIBA Araldite 2010 - test B4Spot-welded - test N4 02Bonded - LOCTITE 330 – test B1Bonded - CIBA Araldite 2010 - test B40510152025300 10 20 30 40 50 60 70 80 90 100displacement [mm]Force [kN]spot weld - piece N4016003spot weld - piece N4016002spot weld - piece N4016001adhesive LOCTITE 330 - piece B1adhesive LOCTITE 330 - piece B5adhesive LOCTITE 330 - piece B30200400600800100012000 10 20 30 40 50 60 70 80 90 100displacement [mm]Energy [J]spot weld - piece N4016003spot weld - piece N4016002spot weld - piece N4016001adhesive LOCTITE 330 - piece B1adhesive LOCTITE 330 - piece B3adhesive LOCTITE 330 - piece B5Stroke (mm)Energy (J)Stroke (mm)Load (kN)40Mean load (kN) Max load (kN)B1 11.62 28.57B3 10.80 27.62B5 11.79 41.75mean value 11.40 32.65stand. dev. 0.53 7.90LOCTITE 330 adhesive iSpot-weldlMean load (kN) Max load (kN)N1 8.09 20.92N2 7.92 21.92N3 7.57 21.41mean value 7.86 21.42stand. dev. 0.26 0.50Quasi-static crushingComparisons (2/2)41•Made with an Ω elements bonded to a flat plate (top-hat section)156060 15sp.1Alternative solutions for improved bonded box (1/2)157060 15sp.110• New shape with two Ωelements one (smaller) inserted into the otherA B42• Bonding flanges as simple substitution of spot-welds•Made with two Ω elements (double hat section)15303060 15sp.1602222sp. 116• Double U section• Can be obtained by joining two identical U elementsSingle-lapjointAlternative solutions for improved bonded box (2/2)C D43Components characteristics Crash-boxes length 300 mm Sheet thickness 0.8 mm Material DC04 (ex FeP04) LOCTITE 330 adhesive procedure:  cleaning and sanding (sand-paper P100) Application of “cleaner” 7063 and activator 7388 Polymerisation for at least 3 days44Quasi-static testsLoad and energy curves C shape: 2 folds followed by global instability and debonding other sections: regular folding some debonding (except D shape)0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 15 mm/minA0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 15 mm/minB0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 15 mm/minC0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 15 mm/minDEnergy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)45Quasi-static tests C shape: 2 folds followed by global instability and debonding other sections: regular folding some debonding (except D shape)46Medium-speed testsLoad and energy curves0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 480 mm/min0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 480 mm/min0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 480 mm/min0100002000030000400000 50 100 150 200Schiacciamento (mm)Carico (N)0750150022503000Energia (J)Vel. 480 mm/minA BC D C shape: 2 folds followed by global instability and debonding other sections: regular folding some debonding (except D shape)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)47Medium-speed tests C shape: 2 folds followed by global instability and debonding other sections: regular folding some debonding (except D shape)4801000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)020040060080010001200Energia (J)Vel. 6.5 m/sCImpact tests (6 m/s) Load and energy curves01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)020040060080010001200Energia (J)Vel. 6.5 m/s01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)020040060080010001200Energia (J)Vel. 6.5 m/s01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)020040060080010001200Energia (J)Vel. 6.5 m/sA BD A, B, C shapes: irregular debonding in the crushed part D shape: no debondingEnergy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)49Impact tests (6 m/s) A, B, C shapes: irregular debonding in the crushed part D shape: no debonding50Impact tests (9 m/s) Load and energy curves01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)04008001200160020002400Energia (J)Vel. 9 m/s01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)04008001200160020002400Energia (J)Vel. 9 m/s01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)04008001200160020002400Energia (J)Vel. 9 m/spicco 62.85 kN01000020000300004000050000600000 50 100 150 200Schiacciamento (mm)Carico (N)04008001200160020002400Energia (J)Vel. 9 m/sA BC D A, B, C shapes: irregular debonding in the crushed part D shape: complete regular folding, no debonding at allEnergy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)Energy (J)Stroke (mm)Load (N)51Impact tests (9 m/s) A, B, C shapes: irregular debonding in the crushed part D shape: complete regular folding, no debonding at all520100002000030000400005000060000Sez. A Sez. B Sez. C Sez. DCarico (N) 15 mm/min480 mm/min6.5 m/s9 m/sValore massimo A, B shapes: maximum load in the average (≈30 kN), good energy absorption characteristics (2÷2.7 kJ)C shape: high maximum load (35 kN), low energy absorption (1.6-0.7 kJ), complete debonding and global instabilityD shape: lowest maximum load (24-28 kN), good energy absorption (1.6-1.8 kJ), regular foldingQuasi-static and medium-speed testsComparison of the different shapes: low speedMaximum load(kN)530100002000030000400005000060000Sez. A Sez. B Sez. C Sez. DCarico (N) 15 mm/min480 mm/min6.5 m/s9 m/sValore massimoC shape: high maximum load (53-63 kN), low compression (50-104 mm); B shape: low maximum load (39 kN) and crushing (57-115 mm); A shape: average maximum load (38-51 kN), high crushing (111-184 mm)D shape: quite low maximum load (39-44 kN), high crushing (83-181 mm), regular foldingComparison of the different shapes: high speedMaximum load(kN)54Conclusions Similar results both from low and medium speed and impact tests Adhesive bonding is a good solution also for energy absorption during crash Sensitive improvements by means of suitable (but simple) geometrical modification of more common shapes used for spot-welded structures:- C shape: bonded sections normal to sides → bad design- D shape: bonded sections parallel to sides →optimal design

Comparison of different joining techniques in a crashworthiness perspective

https://iris.polito.it/retrieve/handle/11583/1412194/46345/20032309-Bremen-Avalle.pdf

Comparison of different joining techniques in a crashworthiness perspective

Abstract

Similar works

Full text

Available Versions

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)