I03 NATIONAL ADAPTATION AND TRANSLATION OF THE CURRICULA EUROPEAN ADHESIVE ENGINEER MODULE 3.4 HYBRID JOINTS ERASMUS + REFERENCE 2015 -I- PT 01- KA202-012915 This project has been co-funded with support from the European Commission. This communication reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein.
Content 1. Types of hybrid joints 2. Advantages and limitations 3. Rules for design 4. Comparison of performance to other joints 5. Influencing factors 6. Practical examples in industry 7. Literature page 3/3-16 page 3/17-28 page 3/29 page 3/30-37 page 3/38-54 page 3/55-58 page 3/59 2
1. Types of hybrid joints The idea of hybrid joints arises from the need of joining together materials, producing a tough, stiff and lightweight joint. The core concept is to use two different joining techniques, with the aim to increase the strength and gather the advantages of each technique, reducing the drawbacks. One of these techniques is adhesive bonding. The first application of this idea was in a Russian airplane in 1960 where resistance spot welding was combined with adhesive bonding. Pirondi & Moroni (2010) 3
1. Types of hybrid joints In practice: bonding + mechanical joining bonding + spot welding self piercing riveting blind riveting screwing clinching setting crimping shrinking 4
1. Types of hybrid joints Examples of hybrid adhesive joints Riveting Spot welding Screwing Clinching Setting, crimping Shrinking Al-Samhann & Darwish (2003) Darwish & Al-Samhann (2004) Darwish (2004) Liu & Sawa (2001) Liu et al. (2004) Grassi et al. (2006) Pirondi & Moroni (2009) Chan & Vedhagiri (2001) Lin & Jen (1999) 5
1. Types of hybrid joints Manufacture Adhesive deposition Adhesive polymerization Riveting / Welding Rivet-through cured adhesive Adhesive deposition Riveting / Welding Adhesive polymerization Rivet-through uncured adhesive Riveting / Welding Adhesive deposition Adhesive polymerization Flow-in 6
1. Types of hybrid joints Manufacture Rivet-bonded joints Rivet-through cured adhesive 1. Adhesive application No risk of contamination of the joining tool Requires additional fixing during adhesive curing Longer process time 2. Assembly 3. Adhesive cure 4. Mechanical joining 7
1. Types of hybrid joints Manufacture Rivet-bonded joints Rivet-through uncured adhesive 2. Assembly 1. Adhesive application 3. Mechanical joining Accurate positioning and fixing of joining parts before adhesive curing Possibility of faster processing of component Adhesive curing can occur at a later manufacturing stage Risk of contamination of the joining tool 4. Adhesive cure 8
1. Types of hybrid joints Manufacture Darwish & Al-Samhann (2004) Weld-bonded joints Flow-in Does not produce any adhesive burning Additional time needed for the adhesive infiltration between the welded parts Weld bonding: (a) the flow-in technique (b) the weld-through technique Weld-through Rapid application The most used in the industry The most severe for the adhesive (a) (b) 9
1. Types of hybrid joints Rivet-bonded joints Two types: Pop rivet bonded joints (PR) Self piercing rivet bonded joints (SPR) Both are joining techniques for sheets, where the joining takes place by means of an external component, called a rivet. 10
1. Types of hybrid joints Rivet-bonded joints Pop rivet bonded joints (PR) Plastic deformation occurs only on the rivet Applicable for almost all the materials Access is required only to one side of the joint is A hole in the part must be made before joining 11
1. Types of hybrid joints Rivet-bonded joints Self piercing rivet bonded joints (SPR) Similar to clinching but a rivet is placed between the plates Plastic deformation of the rivet and the parts Brittle material cannot be joined with this technique The access to both sides of the joint must be ensured and this technique requires a powerful and expensive equipment (if compared with that of PR) 12
1. Types of hybrid joints Rivet-bonded joints Adhesive Characteristics Required The adhesive selection depends on the mechanical performance desired for the joint For achieving high joint strength- Stiff and strong adhesive (typically an epoxy structural adhesive) For sealing purposes - Flexible but also weak adhesive (typically a sealant like silicone) The joint strength is provided by the rivet while the adhesive has only sealing properties The classic pop rivets cannot properly be used as they have a hole where the mandrel is placed 13
1. Types of hybrid joints Weld-bonded joints Adhesive Characteristics Required Heat curing paste type adhesives are normally used as these are stable and have a consistent viscosity at room temperature. Typically, such adhesives are cured in an oven at up to 180 C for 30 min. Some adhesives are available in tape form and incorporate metal particle filler which allows initial electrical contact to be made for spot welding. 14
1. Types of hybrid joints Clinch adhesive joints Also called clinchbonded joints, they are of particular interest for the chassis manufacturing in vehicles (automotive, trucks, buses, railways) but also for nautical and ropeways applications. Production Clinching technology is a method of joining different metal parts by a process of local deformation achieved with the use of a punch and a die and without any additional elements The TOX clinching model Sadowski & Balawender (2011) The mechanisms of locking of joining parts during the clinching process 15
1. Types of hybrid joints Clinch adhesive joints Adhesive Characteristics Required The types of adhesive layers in clinch adhesive joints are presented in figure. One can distinguish two types of interfaces at the joined materials created by different types of glues: (a) two component adhesive for metal joining and (b) acrylic pressure sensitive tape. (a) - the strength of the hybrid joints highly depends on the type of applied adhesives Types of adhesive layers in hybrid joints: (a) Two component adhesive (b) Pressure sensitive adhesive (b) - quick-fix properties of joined components, good viscoelastic properties under impact loading and vibration damping properties Sadowski & Balawender (2011) 16
2. Advantages and limitations Advantages High strength and stiffness High energy absorption at failure High fatigue strength High corrosion resistance Allows lightweight designs Low cost of manufacture Pirondi & Moroni (2010) Allows to hold the parts together during the adhesive s polymerization without any other tool Allows the joining of different materials (including a multi-layer, an insulation layer) with large differences in thickness 17
2. Advantages and limitations Advantages Can be controlled with non-destructive testing the quality of joint can be checked visually or with the application of simple measurement techniques The issue of predicting long-term performance of the bonded joint is avoided since bonding is being combined with a proven joining method No thermal influence on the joined materials microstructure Improved noise-damping properties Seals the joint against moisture and aggressive environment Pirondi & Moroni (2010) Sadowski & Balawender (2011) 18
2. Advantages and limitations Limitations Requires heat curing (when thermosetting adhesive is used) Relatively weak peeling strength Sensitiveness to ageing process Limited strength under thermal loading Sadowski & Balawender (2011) 19
2. Advantages and limitations Bonding Planar force transmission High material utilisation High potential light structures High component stiffness High dynamic strength Fixing necessary until adhesive is cured Tendency to creep Low peeling strength Dependent on temperature and time Mechanical Fastening High process reliability Immediately useable High strength Poor material utilisation Permeable between two joints Risk of crevice corrosion Hybrid Joint Additional fixing of the joining parts until adhesive is cured is required Improvement of the strength properties and/or the material utilisation Corrosion protection particularly for different joining materials 20
2. Advantages and limitations Rivet-bonded joints Advantages Easier and trouble free manufacturing when compared with weld bonded joints Limitations Lower performance when compared with weld bonded joints 21
2. Advantages and limitations Screw-bonded joints Advantages Bolts may help a bonded joint survive exposure to fire. In such cases the adhesives soften and lose strength but the bolts will carry the load. Easy to assemble with basic tools Limitations Electrical continuity is interrupted by the adhesive layer. 22
2. Advantages and limitations Weld-bonded joints Advantages The most deeply studied hybrid joint configuration Hybrid joining technique where better results are obtained High static strength Improved fatigue strength Allows the elimination of additional sealing operations Improved corrosion resistance Provides a joining process quieter than the use of rivets Darwish & Al-Samhann (2004) 23
2. Advantages and limitations Weld-bonded joints Advantages Reduced manufacturing costs and adaptability to mechanization Excellent acoustical properties Limitations Requires a complex joint manufacturing process Weld compliant adhesive are required to avoid excessive burn-out or damage 24
2. Advantages and limitations Clinch adhesive joints The application of pure clinching technology has many advantages for the automotive (mass production) and aeronautics (small series production) industry. Advantages Green assembly method no fumes, emissions or high electric currents Ergonomic for operation and easy for automation does not require, for example, pre-drilling holes or other pre-treatment Very long lifetime of the tooling set (including the punch, the die and the blank holder) The manufacturing process consumes little energy in comparison to spot-welding Simple set-up 25
2. Advantages and limitations Clinch adhesive joints Advantages A similar speed of operation in comparison to the spot-welding technique Allows the joining of pre-coated materials, rubber gasket materials and sandwich plates Economically attractive low capital and operation costs The clinch type of joint causes more favourable stress distributions and stress concentrations associated with design Easier and less complex manufacturing when compared with weld bonded joints 26
2. Advantages and limitations Clinch adhesive joints Limitations Requires access to both sides of the joint Restricted access to some joint areas due to size of the gun required Weak gas and fluid tightness Weak prevention of corrosion due to surface irregularities 27
2. Advantages and limitations It is important to recognise that hybrid joining techniques need to be adapted to each individual case if maximum reliability is to be achieved. Sadowski & Balawender (2011) 28
3. Rules for design When designing a bonded joint, you should not forget adhesives resist well to compression, pure tensile stress and shear adhesive are rather sensitive to cleavage and peeling There are no optimal geometrical parameters for hybrid adhesive joints The geometrical configuration should be finely tuned for each case Several authors have studied varied configurations of hybrid adhesive joints, demonstrating the importance of the geometrical configuration and material properties 29
4. Comparison of performance to other joints Rivet-bonded joints The performance of hybrid joints depends mostly on the strength of the adhesive bond, and the rivet becomes relevant only when the adhesive performance decreases (i.e. when the service temperature is higher than the adhesive glass transition temperature for example) or in general when the adhesive fails. Pirondi & Moroni (2010) 30
4. Comparison of performance to other joints Rivet-bonded joints Sadowski et al. (2013) Sadowski et al. (2013) Stress distribution during the rivet shearing in the hybrid joint (in [Pa]) von Mises stress in the final stage of degradation process of the hybrid joint. After total decohesion of the adhesive layers shearing rivet process initiates and leads to final failure. Load-displacement curves for the riveted joints, the adhesive joints and the hybrid joints 31
4. Comparison of performance to other joints Rivet-bonded joints Pirondi & Moroni (2010) Simple riveted joints Comparison of load-displacement curves of simple bonded, simple pop riveted and hybrid joints 32
4. Comparison of performance to other joints Rivet-bonded joints Pirondi & Moroni (2010) Simple riveted joints Comparison of load vs displacement plot of a hybrid pop riveted joint and a simple pop riveted joint shifted of the value of the displacement at the strength of the hybrid riveted joint 33
4. Comparison of performance to other joints Rivet-bonded joints Pirondi & Moroni (2010) Simple riveted joints Comparison of load-displacement curves of simple bonded, simple self piercing riveted and hybrid joints 34
4. Comparison of performance to other joints Clinch adhesive joints Adhesive Pattex Repair Epoxy Sadowski et al. (2013) Adherends ETP-copper Low carbon steel Joint geometry Single lap joint 132 35 1 mm 35 mm overlap Experimental load displacement curves obtained for adhesive, clinched and hybrid joints. 35
4. Comparison of performance to other joints Clinch adhesive joints Sadowski et al. (2013) Test methods for estimation of quality of clinched joints: (a) peel tension, (b) tensile shear Simulated separation force evolution in the pull test -comparison between: clinching before curing and clinching after curing 36
4. Comparison of performance to other joints Welded-spot adhesive joints a) Specimen dimensions, b) experimental load-displacement curve with corresponding DIC strain distribution Sadowski et al. (2013) 37
5. Influencing factors Rivet-bonded joints Pirondi & Moroni (2010) Specimens with one or two rivets, respectively, representing a pitch of 60 mm (a) and 30 mm (b) Factors evaluated and their levels in the experimental campaign Adherends Galvanized steel (S 275) Aluminum alloy (AA 5052) Joint geometry Single lap joint 100 60 mm 15 mm overlap Adhesive Henkel Terokal 5077 Definition of temperature levels 38
5. Influencing factors Rivet-bonded joints Pirondi & Moroni (2010) Comparison of load-displacement curves of simple bonded, simple pop riveted and hybrid joints Average value and influence of factors for simple bonded, pop riveted and pop rivet bonded joints 39
5. Influencing factors Rivet-bonded joints Pirondi & Moroni (2010) Comparison of load-displacement curves of simple bonded, simple self piercing riveted and hybrid joints Average value and influence of factors for simple bonded, self piercing riveted and self piercing rivet bonded joints 40
5. Influencing factors Tensile shear strength of Spot Welded and Weldbonded joints Gaul & Weber (2011) Tensile shear forces for weldbonded and spot welded joints Specimen geometry for the mechanical tests (all dimensions in mm, not to scale) 41
5. Influencing factors Tensile shear strength of Spot Welded and Weldbonded joints Advanced high strength steels (AHSS) Ultra high strength steels (UHSS) BetamateTM 1480 Influence of the base metal strength on the strength of weldbonded (WB2) and spot welded (RSW) joints for same base metals, with weld diameters (in columns) Gaul & Weber (2011) 42
5. Influencing factors Tensile shear strength of Spot Welded and Weldbonded joints Advanced high strength steels (AHSS) Ultra high strength steels (UHSS) BetamateTM 1480 Influence of the base metal strength on the strength of weldbonded (WB2) and spot welded (RSW) joints for base metal combinations, with weld diameters (in columns) Gaul & Weber (2011) 43
5. Influencing factors Tensile shear strength of Spot Welded and Weldbonded joints Gaul & Weber (2011) Difference of the tensile shear forces T S between RSW and WB joints for the same and different base metals 44
5. Influencing factors Tensile shear strength of Spot Welded and Weldbonded joints Tensile shear forces and absorbed energies for weldbonded and spot welded joints Gaul & Weber (2011) 45
5. Influencing factors Fatigue behaviour of Spot Welded and Weldbonded joints Gaul & Weber (2011) Terostat 5194 (WB1) BetamateTM 1480 (WB2) SikaPower-498 (WB3) Tensile shear force of the base metal combination HCT780T/HCT600X spot welded (RSW) and weldbonded with different adhesives under (a) quasi-static shear load and (b) impact shear load Absorbed energy of the base metal combination HCT780T/HCT600X spot welded (RSW) and weldbonded with different adhesives (a) under quasi-static and (b) impact shear load 46
5. Influencing factors Clinch adhesive joints Strength and Durability Sadowski & Balawender (2011) Typical clinch joint shearing strengths obtained for different materials Geometry of the overlap specimen 47
5. Influencing factors Clinch adhesive joints Strength and Durability Mechanical properties of materials used in the tests Sadowski & Balawender (2011) Clinching tools geometry 48
5. Influencing factors Clinch adhesive joints Strength and Durability Sadowski & Balawender (2011) Experimental load displacement curves obtained for clinched joints 49
5. Influencing factors Clinch adhesive joints Strength and Durability Sadowski & Balawender (2011) Experimental load displacement curves (clinched and hybrid) obtained for steel steel joints Experimental load displacement curves (clinched and hybrid) obtained for steel copper joints 50
5. Influencing factors Clinch adhesive joints Strength and Durability Sadowski & Balawender (2011) Experimental load displacement curves (clinched and hybrid) obtained for brass copper joints Experimental load displacement curves (clinched and hybrid) obtained for copper copper joints 51
5. Influencing factors Clinch adhesive joints Strength and Durability Sadowski & Balawender (2011) The mechanical strength of hybrid clinch adhesive joints strongly depends on the adhesive and adherends properties. The introduction of adhesives into clinching joints essentially changes the mechanical strength. Experimental load displacement curves (clinched and hybrid) obtained for brass brass joints 52
5. Influencing factors Clinch adhesive joints Strength and Durability Sadowski & Balawender (2011) Energy absorption of the clinched and hybrid lap joints 53
5. Influencing factors Clinch adhesive joints Sadowski & Balawender (2011) The mechanical strength of hybrid clinch adhesive joints strongly depends on the adhesive and adherends properties. The introduction of adhesives into clinching joints essentially changes the mechanical strength. Experimental load displacement curves (clinched and hybrid) obtained for brass brass joints 54
6. Practical examples in industry In which industries are hybrid joints applied? Automotive Aerospace Aeronautic Nautical Shipbuilding Gaul & Weber (2011) Length of applied adhesives and number of spot welds for different car body shell construction 55
6. Practical examples in industry BMW Z8 Clinch joints in a car bonnet 56
6. Practical examples in industry Welded-spot adhesive joints in car body steels for the automotive industry Riveting adhesive joint in wing skins for the aerospace industry 57
6. Practical examples in industry Weitzenböck & George (2011) Example of butt-strap riveted joint for vehicle frame applications Pirondi & Moroni (2010) Bonded windows for cruise ships 58
6. Practical examples in industry Example of bolted, adhesively bonded joint for structural applications Example of bolted, adhesively bonded joint for wind turbine blade construction 59
7. Literature Al-Samhan, A., and Darwish, S.M.H. (2003). Strength prediction of weld-bonded joints. Int. J. Adhes. Adhes. 23, 23 28. Chan, W.S., and Vedhagiri, S. (2001). Analysis of composite bonded/bolted joints used in repairing. J. Compos. Mater. 35, 1045 1061. Darwish, S.M., and Al-Samhan, A. (2004). Thermal stresses developed in weld-bonded joints. J. Mater. Process. Technol. 153, 971 977. Grassi, M., Cox, B., and Zhang, X. (2006). Simulation of pin-reinforced single-lap composite joints. Compos. Sci. Technol. 66, 1623 1638. Liu, J., and Sawa, T. (2001). Stress analysis and strength evaluation of single-lap adhesive joints combined with rivets under external bending moments. J. Adhes. Sci. Technol. 15, 43 61. Sadowski, T., Balawender, T., Sliwa, R., Golewski, P., and Knec, M. (2013). Modern hybrid joints in aerospace: modelling and testing/nowoczesne Po\laczenia Hybrydowe W Lotnictwie: Modelowanie I Badania Eskperymentalne. Arch. Metall. Mater. 58, 163 169. da Silva, L.F., Pirondi, A., and Ochsner, A. (2011). Hybrid adhesive joints (Springer Science & Business Media). 60