Table of Contents

Cover

Title Page

List of Contributors

Preface

Part I: Joining Processes Based on Adhesion Forces

Chapter 1: Principles of Adhesive Bonding
1. 1.1 Introduction
2. 1.2 General Basics
3. 1.3 Advantages and Disadvantages of Adhesive Bonding
4. 1.4 Effect of Surface Preparation and the Environmental Factors
5. 1.5 Adhesive Properties
6. 1.6 Joint Manufacture
7. 1.7 Joint Design
8. 1.8 Recent Developments
9. 1.9 Conclusions
10. References
Chapter 2: Adhesive Bonding of Polymer Composites to Lightweight Metals
1. 2.1 Introduction
2. 2.2 Characteristics and Applications of Hybrid Bonding
3. 2.3 Experimental Evaluation of Hybrid Structures
4. 2.4 Predictive Techniques for Hybrid Structures
5. 2.5 Conclusions
6. List of Abbreviations
7. References
Chapter 3: Friction Spot Joining (FSpJ)
1. 3.1 Introduction
2. 3.2 Principles of the FSpJ
3. 3.3 Heat Generation During FSpJ Process
4. 3.4 Microstructural Zones in FSpJ
5. 3.5 Mechanical Properties of FSp Joints
6. 3.6 Comparison Between the Quasistatic Mechanical Performance of FSp and State-of-the-Art Adhesively Bonded Joints
7. 3.7 Defects in FSpJ
8. 3.8 Advantages, Limitations, and Potential Applications
9. 3.9 Final Remarks
10. References
Chapter 4: Induction Welding of Metal/Composite Hybrid Structures
1. 4.1 Introduction
2. 4.2 Description of the Principles of the Joining Technique
3. 4.3 Mechanical Performance of Induction Welds in Comparison to Adhesive Bonding
4. 4.4 Advantages and Limitations
5. 4.5 Applications
6. 4.6 Available Equipment and Tools
7. 4.7 Further Reading and Additional Literature
8. References
Chapter 5: Direct Joining of Metal and Plastic with Laser
1. 5.1 Introduction
2. 5.2 Direct Joining Procedures of Metal and Plastic with Laser (LAMP Joining Procedure)
3. 5.3 Features and Mechanical Properties of Metal–Plastic Laser Joints (LAMP Joints)
4. 5.4 Mechanisms of LAMP (Laser-Assisted Metal and Plastic) Direct Joining
5. 5.5 Reliability Evaluation Tests
6. 5.6 Evolution of LAMP Joining
7. 5.7 Conclusions
8. References

Part II: Joining Processes Based on Mechanical Interlocking

Chapter 6: Principles of Mechanical Fastening in Structural Applications
1. 6.1 Introduction
2. 6.2 General Joint Structural Design
3. 6.3 Shear Joints
4. 6.4 Tension Joints
5. 6.5 Tolerances in Joint Design
6. 6.6 Materials
7. 6.7 Fasteners
8. 6.8 Summary and Final Remarks
9. References
Chapter 7: Mechanical Fastening of Composite and Composite–Metal Structures
1. 7.1 Introduction
2. 7.2 Semianalytical Method for the Design of Composite Joints
3. 7.3 Numerical Method for the Design of Composite Joints
4. 7.4 Conclusions
5. Acknowledgments
6. References
Chapter 8: Friction Riveting of Polymer–Metal Multimaterial Structures
1. 8.1 Introduction
2. 8.2 FricRiveting: Principles of the Technique
3. 8.3 FricRiveting: Process Parameters and Variables
4. 8.4 FricRiveting: Process Phases and Heat Generation
5. 8.5 Thermal History
6. 8.6 Microstructure
7. 8.7 Physical–Chemical Changes in the Polymeric Material
8. 8.8 Mechanical Performance
9. 8.9 Envisaged Applications
10. 8.10 Conclusions
11. Acknowledgments
12. References
13. List of Awards and Prizes Received by Works on FricRiveting
Chapter 9: Staking of Polymer–Metal Hybrid Structures
1. 9.1 Introduction
2. 9.2 Types of Staking Processes
3. 9.3 Characteristics of Staked Joints
4. 9.4 Design Considerations for Staked Joints
5. 9.5 Mechanical Behavior of Staked Joints
6. 9.6 Final Remarks
7. List of Abbreviations
8. References

Part III: Joining Processes Based on Direct-Assembly Methods

Chapter 10: Injection Overmolding of Polymer–Metal Hybrid Structures
1. 10.1 Basics of Polymer–Metal Hybrid Technology
2. 10.2 Classification of PMH Technologies
3. 10.3 Mechanisms for Polymer/Metal Joining
4. 10.4 Computational Engineering Analyses of PMH Technologies
5. 10.5 Compatibility with Automotive BIW Manufacturing Process Chain
6. 10.6 Concluding Remarks
7. References
Chapter 11: Ultrasonic Joining of Lightweight Alloy/Fiber-Reinforced Polymer Hybrid Structures
1. 11.1 Introduction
2. 11.2 MIMStruct Manufacturing Route
3. 11.3 U-Joining: Principles of the Process
4. 11.4 Case Study on Ti-6Al-4V/GF-PEI Joints
5. 11.5 Advantages and Limitations
6. Acknowledgments
7. References

Part IV: Design of Experiments and Statistical Analysis in Joining Process Development

Chapter 12: Factorial Design of Experiments for Polymer–Metal Joining
1. 12.1 Introduction
2. 12.2 Design of Experiments
3. 12.3 Final Remarks
4. References
Chapter 13: Taguchi Design and Response Surface Methodology for Polymer–Metal Joining
1. 13.1 Introduction
2. 13.2 The Taguchi Design of Experiments
3. 13.3 Example of Taguchi Design of Experiments in Joining of Metal to Composite Structures
4. 13.4 Response Surface Methodology
5. 13.5 Other Surface Designs
6. 13.6 Final Remarks
7. References
Index

End User License Agreement

List of Illustrations

Chapter 1: Principles of Adhesive Bonding

Figure 1.1 Components of an adhesively bonded joint.
Figure 1.2 Average lap shear strength of AV118 epoxy adhesive as a function of temperature.
Figure 1.3 Bondline thickness control with spacers.
Figure 1.4 Failure modes.
Figure 1.5 Strength of singularities in lap joints.

Chapter 2: Adhesive Bonding of Polymer Composites to Lightweight Metals

Figure 2.1 Single- and double-lap hybrid joints (a) and hybrid reinforced panel (b).
Figure 2.2 Examples of FML between unidirectional composite plies and aluminum layers.
Figure 2.3 Optical micrographs of impacted 4/3 FML at the impacted surface (a) and at the rear surface (b).
Figure 2.4 Fatigue crack growth rate versus crack length for nonreinforced and reinforced panels without impact damage; (a) and fatigue crack length versus number of cycles for reinforced, nonimpacted, and impacted panels (b).
Figure 2.5 Hybrid joint configurations tested (a) and yielding load FE predictions for the titanium–composite joints (b).
Figure 2.6 A hybrid reinforced specimen of aluminum–Glare.
Figure 2.7 Experimental and FE P–δ curve chordwise specimens without butt joints (continuous fiber layers) (a) and chordwise with butt near the mid span of the stringer (b).
Figure 2.8 FE-test data postimpact damage comparison for 2/1 (a) and 4/3 hybrid plates (b).

Chapter 3: Friction Spot Joining (FSpJ)

Figure 3.1 Illustration of the FSpJ tool; (a) consisting of three parts (dimensions in millimeters) and (b) tool parts coaxially mounted together.
Figure 3.2 (a) A photo of the RPS100 welding head, the assembled tool, welding table, the pneumatic piston and (b) a magnified image of the welding head and table showing the upstroke in the equipment.
Figure 3.3 Configuration of the joining parts and the FSpJ tool before the process starts.
Figure 3.4 Schematic representation of the FSpJ process steps; (a) the sleeve plunging plasticizes the metal, (b) spot refilling, and (c) joint consolidation.
Figure 3.5 Top view of a sound metal–composite FSp joint; (Ex.: AA2024/CF-PPS).
Figure 3.6 Schematic illustration of the spot area showing the impression of the tool parts on the top surface of the metal; (a) top view and (b) 3D view.
Figure 3.7 Example of a cross section of an FSp joint in the middle of the spot. The rectangle indicates the nub, and the red circles show the gap formation below the plunging sleeve; (Ex.: AA2024/CF-PPS).
Figure 3.8 Schematic illustration of the cross section of the middle of the spot area. A nub reservoir is formed that accommodates the molten polymer. The composite partner is omitted for better visualization.
Figure 3.9 Comparison of the nub shape in case of (a) a continuous fiber-reinforced composite and (b) a short fiber-reinforced composite; (Ex.: AA2024/CF-PPS).
Figure 3.10 Comparison of the gap formed on the surface of the metal with a PD of (a) 0.8 mm and (b) 0.5 mm. The dashed lines display the midplane between metal and composite before the joining process. The arrows in (b) indicate the two bumps helping the keyhole filling; (Ex.: AA2024/CF-PPS).
Figure 3.11 (a) Illustration of the adhesion forces as one of the primary bonding mechanisms in FSpJ and (b) an example of the fracture surface of an FSp joint tested by lap shear; (Ex.: AA2024/CF-PPS).
Figure 3.12 (a) Schematic fracture surface of an FSp joint and (b) real fracture surface of an AA2024/CF-PPS FSp joint, indicating three bonding zones; plastically deformed zone (PDZ), transition zone (TZ), and adhesion zone (AZ).
Figure 3.13 Cross section of an AA2024/CF-PPS FSp joint in the PDZ examined by LSCM showing micromechanical interlocking through (a) aluminum pore/crevice filling by the molten PPS in a resin-rich area and (b) fiber entrapment. (Adapted from Ref. [30].) (c) High-magnification SEM image showing a thin layer of the PPS between aluminum and carbon fibers.
Figure 3.14 Microstructural zones that form in the aluminum. (a) General overview of the joints microstructure, (b) microstructure in the BM, (c) MTMAZ showing elongated grains rotated compared to the BM grains, (d) boundary between MTMAZ and MSZ, (e) MSZ showing very fine DRX grains, and (f) boundary between MTMAZ and MHAZ.
Figure 3.15 Microstructure of an AA2024/CF-PPS joint. Dashed line indicates the boundary between PHAZ and BM.
Figure 3.16 Microhardness map of the AA2024 from the edge of the specimen (x = 0 mm) to the middle of the spot (x = 12.5 mm) in an AA2024/CF-PPS joint.
Figure 3.17 (a) Microstructure of an Mg AZ31/GF-PPS joint showing three microhardness lines on the composite and (b) hardness variation of the short glass-fiber-reinforced PPS according to the selected lines in (a).
Figure 3.18 Mechanical strength of single-lap shear AA2024/CF-PPS FSp joints after aluminum surface pretreatments.
Figure 3.19 Double-lap joint configuration, (a) aluminum–composite–aluminum (ACA) sequence and (b) aluminum–aluminum–composite (AAC) sequence.
Figure 3.20 (a) Comparison of force–displacement curves of single-lap shear and double-lap shear AA2024/CF-PPS joints and (b) mechanical strength of double-lap shear joints after aluminum surface pretreatments.
Figure 3.21 (a) Force–displacement curve of an AA6181/CF-PPS double-lap joint according to the AAC configuration, (b) sequence of the joint failure under quasistatic lap shear testing, and (c) fracture surface of the aluminum sheets and composite of a failed specimen.
Figure 3.22 (a) Schematic illustration of the CT joint geometry and (b) top view of the joint design with the respective dimensions used. All dimensions are in millimeter.
Figure 3.23 Cross-tensile strength of an AA2024/CF-PPS FSp joint after selected aluminum surface pretreatments.
Figure 3.24 Comparison of the S–N curves of the various surface pretreatment specimens based on the exponential model (AA2024/CF-PPS).
Figure 3.25 Deconsolidation defects in the composite with FSpJ, showing (a) voids in the consolidated molten layer and (b) fiber–matrix debonding; (Ex.: AA2024/CF-PPS).
Figure 3.26 Illustration of a broken stir zone (BSZ) that occurs in the metal part; (a) top view of the metal part and (b) cross section of the joint in (a) at the center of the spot; (Ex.: AA2024/CF-PPS).
Figure 3.27 Mechanism of the BSZ formation; (a) excessive sleeve plunge, (b) initiation of micro cracks in the metal, (c) propagation of the crack, and (d) formation of the BSZ.
Figure 3.28 Schematic illustration of potential FSpJ applications; (a) in the aircraft structure, to join (b) a metal skin to a composite skin and (c) a metal stringer to the composite skin.
Figure 3.29 Skin–stringer aluminum–composite subcomponent produced with FSpJ.

Chapter 4: Induction Welding of Metal/Composite Hybrid Structures

Figure 4.1 Experimental setup of a discontinuous induction welding apparatus.
Figure 4.2 Principle of induction heating in induction-welded hybrid joints.
Figure 4.3 Hysteresis curves of soft and hard magnetic materials.
Figure 4.4 Different inductors and their heating patterns ((a) Butterfly; (b) Pancake; and (c) Pancake with flux concentrator) in carbon-fiber-reinforced composite laminates.
Figure 4.5 Current density inside different materials (f = 1 MHz).
Figure 4.6 Dependence of the penetration depth to the frequency.
Figure 4.7 Different adhesion models.
Figure 4.8 Surface roughness (R_a) of AlMg₃ alloy with different surface treatment methods.
Figure 4.9 Comparison of the surface free energies of AlMg₃ alloy in dependence of the surface pretreatment (calculated according to the Owens–Wendt–Rabel–Kaelble method).
Figure 4.10 Comparison of the surface free energies of CF/PA66 in dependence of the surface pretreatment (calculated according to the Owens–Wendt–Rabel–Kaelble method).
Figure 4.11 Influence of the surface pretreatment on the shear tensile strength of AlMg₃/CF-PA66 induction welds.
Figure 4.12 Deconsolidation of GF-PP composites.
Figure 4.13 Influence of the sheet's thickness in the welding zone on the lap shear strength of (AlMg₃/-CF-/PA66) induction welds [1].
Figure 4.14 Three-phase discontinuous induction welding process setup.
Figure 4.15 Three-phase discontinuous induction welding process temperature profile and pressure (the pressure is presented qualitative without Y-axis).
Figure 4.16 Induction spot-welding setup.
Figure 4.17 Induction spot-welding process temperature profiles and pressure (the pressure is presented qualitative without Y-axis).
Figure 4.18 Spot-welding temperature distribution within the welding zone.
Figure 4.19 Comparison of the mechanical performance of inductive welded and adhesively bonded samples.

Chapter 5: Direct Joining of Metal and Plastic with Laser

Figure 5.1 3 kW diode laser apparatus, jig, and stage and their arrangement for LAMP joining.
Figure 5.2 Features of power density distribution and mode of YAG laser beam (a) and diode laser beam (b). In (a), the focusing of the YAG laser beam is shown as a function of defocused distance, mode, power density, and beam diameter. In (b), the diode laser beam power density distribution, mode, and traveling direction are detailed.
Figure 5.3 Schematic experimental setup of laser-assisted metal and plastic (LAMP) direct joining methods using various lasers: (a) YAG laser irradiation for transparent plastic, (b) diode laser irradiation for transparent plastic, and (c) fiber laser irradiation for nontransparent plastic. Feasible materials combinations and their joining parameters are shown in the schematics.
Figure 5.4 Surface appearances of LAMP joint of amorphous PA6 and Type 304 Type 304 sheets made with YAG laser at f_d = 20 mm and welding speed v = 10 mm/s. Detailed picture shows small bubbles in the weld seam.
Figure 5.5 Effect of YAG laser power on weld seam of LAMP joints of amorphous PA6 and stainless steel Type 304 sheets. (Joining parameters: defocused distance, f_d: 20 mm; traveling speed, v: 10 mm/s; Ar gas flow rate: 50 L/min).
Figure 5.6 LAMP joints after tensile shear test, showing fracture in base PA (a) and elongation of base PET (b).
Figure 5.7 Effects of the laser power and defocused distance on the tensile shear loads of LAMP joints between Type 304 stainless steel and amorphous PA6 produced with YAG laser.
Figure 5.8 Effect of traveling speed on tensile shear loads of LAMP joints of Type 304 stainless steel and amorphous PET made with diode laser of line-shaped beam.
Figure 5.9 Surface appearances of LAMP joint of Type 304 stainless steel and amorphous PA sheets produce by laser irradiation on metal surface, showing partial melting of Type 304, partial melting of PA near interface (a), and formation of bubbles in melted PA (b).
Figure 5.10 Effects of YAG laser irradiation direction and laser power on tensile shear load of LAMP joint of Type 304 stainless steel and amorphous PA6.
Figure 5.11 High-speed video observation results near laser irradiation part during LAMP joining of PA sheet lapped on Type 304 stainless steel plate: (a) laser power of 215 W, (b) laser power of 310 W, and (c) laser power of 560 W.
Figure 5.12 High-speed video and thermometer observation results of bottom side of Type 304 plate during LAMP joining: (a) high-speed image and (b) thermometer observation.
Figure 5.13 Q-mass spectrometer measurement results showing ejection of various gases from entrapped bubbles (a) and compositions and amount of gases released from the bubbles and background (b).
Figure 5.14 SEM and TEM observations and analysis results of LAMP joint of Type 304 stainless steel and amorphous PET produced with diode laser. a) Metal-polymer interface with small bubbles; b) Detailed view of the metal-polymer interface showing polymer infiltrated in the natural oxide film covering the metal.
Figure 5.15 (a) SEM photo of LAMP joint between surface mechanically treated AZ91D and amorphous PET produced with diode laser and (b) EDX analytical results of areas inside (a) Mg pore, showing plastic-melt flow into pit.
Figure 5.16 Schematic representation of mechanisms of laser direct joining process of metal and plastic (LAMP joining process).
Figure 5.17 Schematic and actual leakage test procedure and leakage measurement results of LAMP joints. (Notation: Judgment “OK”: joint passed test; Judgment NG (not good): joint did not pass test).
Figure 5.18 Heat-shock test results of LAMP joints of Type 304 and PET. (Fracture load of specimen before shock test: 2900 N).
Figure 5.19 Schematic joining process of dissimilar Type 304 stainless steel and AA 5052 sheets with PET interlayer plate.
Figure 5.20 Mechanical test results (stress–strain curve) and fractured sample of dissimilar Type 304 stainless steel and AA5052 sheets with PET interlayer plate.
Figure 5.21 Tensile shear test results of Type 304 stainless steel and CFRP sheets LAMP joints (a), and specimen example, joint cross section, and magnified photo near joint interface showing bubbles in CFRP (b).

Chapter 6: Principles of Mechanical Fastening in Structural Applications

Figure 6.1 Types of joints (general). (a) Lab joint, single shear; (b) butt joint, double shear; (c) axial (no bending); (d) tension and bending.
Figure 6.2 Static failure modes in joints
Figure 6.3 Representation of load transfer through a fastened lap joint with three rows of rivets.
Figure 6.4 Stress concentration around fastener holes – influence of bearing and bypass loads.
Figure 6.5 Stress profiles (schematic) for different remote loading conditions.
Figure 6.6 Detailed FEM model analysis results – model with solid elements, contact between upper and lower plate, and contact between fastener and holes.
Figure 6.7 Plate and neutral line deflection for a three-rivet lap joint
Figure 6.8 Schematic representation of MSD (multisite damage) in a fuselage lap joint.
Figure 6.9 Typical residual stresses after welding (a) in the transversal direction (b) in the longitudinal direction.
Figure 6.10 Spring system as an idealization of a bolted tension joint
Figure 6.11 Possible bolted joint configurations: (a) structure is resting, (b) a pretorque is applied, and structure withstands a constant load P_t (mean value), (c) structure is subjected to external (working loads) without reaching the load P_t due to pretorque, (d) working load becomes higher than pretorque, and there is separation of the members
Figure 6.12 Diagrams relating component loads with (a) joint global displacement and (b) applied loads
Figure 6.13 Schematic representation of the prying effect.
Figure 6.14 Example of FEM analysis in bolted joint. (a) Model with solid elements and axisymmetric boundary conditions, (b) compressive stress fringes (Z stress), stresses in MPa.
Figure 6.15 Some considerations about tolerances during joint assemblies.

Chapter 7: Mechanical Fastening of Composite and Composite–Metal Structures

Figure 7.1 Typical failure modes in composite bolted joints.
Figure 7.2 Geometry and loading of the composite lap.
Figure 7.3 Failed joints with different w/d ratios.
Figure 7.4 Modeling strategy.
Figure 7.5 Schematic representation of bridged transverse crack.
Figure 7.6 Linear traction–displacement jump relation.
Figure 7.7 Total strain, elastic strain, and cracking strain.
Figure 7.8 Damaged elastic modulus.
Figure 7.9 Mesh of bolted joint.
Figure 7.10 Damage variable for the fully failed joint.

Chapter 8: Friction Riveting of Polymer–Metal Multimaterial Structures

Figure 8.1 Friction riveting process scheme as illustrated for “point-on-plate” joints. (a) Positioning and clamping of joining partners. (b) Rotational insertion of the rivet into the polymeric base plate. (c) Rotational breaking followed by (d) Rivet forging. (e) Joint consolidation
Figure 8.2 Scheme of joining equipment RSM 400 used for FricRiveting.
Figure 8.3 The RNA FricRiveting equipment.
Figure 8.4 Schematic experimental monitoring diagram with the main FricRiveting process parameters and variables (e.g., for the time-controlled process variant).
Figure 8.5 Process phases in FricRiveting: P-I: Coulomb Friction (solid friction). P-II: Unsteady-State Viscous Dissipation. P-III: Steady-State Viscous Dissipation. P-IV: Rivet Forging Phase. P-V: Consolidation Phase.
Figure 8.6 (a) Average experimental peak temperatures obtained for a 21,000 rpm, 3 s, 1.1 MPa Al 2024-T351/PEI friction-riveted joint, (b) Schematics of thermocouple disposition, (c) IR camera positioning.
Figure 8.7 (a) Example of the process temperature history of FricRiveting joints measured in polymeric flash material for three samples produced with 18,000 rpm, 3 s, and 1.10 MPa. (b) Average peak temperatures for PC/AA 2024-T351 joints
Figure 8.8 (a) Thermogram (IR snapshot) showing the temperature distribution of the softened PEEK composite flash material being expelled from the joining region and pushed to the surface and the location of the measurement area. (b) Example of process temperature evolution during FricRiveting a metallic-insert CF-PEEK/Ti gr. 3joint
Figure 8.9 (a) Evolution of the maximum temperature during the process measured by infrared thermography. (b) thermogram showing the maximum temperature of the softened composite flash material being expelled out of the composite plate, the dash-lined rectangle is the measuring area for friction-riveted GF-PA6/AA 6056-T6 joints
Figure 8.10 Monitored average peak IR temperatures of GF-PEI/Ti gr. 2 friction-riveted joints
Figure 8.11 X-ray image of a metallic-insert joint
Figure 8.12 μCT results showing a metallic-insert joint type in PEI/Al 2024. Three different segmented volumes are represented from the top-right-hand side to the bottom of the picture: the nontreated PEI volume, the PEI volume containing thermomechanical treated polymer and the deformed tip of the Al 2024-T351 rivet (the anchoring zone)
Figure 8.13 Schematic representation of the typical microstructural zones found in FricRiveting joints
Figure 8.14 Microstructural features of a cross-sectioned metallographic insert-type FricRiveting joint on PEI/Al 2024-T351 (21,000 rpm, 3 s, and 1.1 MPa): (a) nonetched polished LOM macrograph; (b) detailed photo of region B in (a) showing the partially dynamically recrystallized grain distribution in the MTHAZ (electrolytic etching with Barker solution – 200 mL distilled water, 5 g fluoboric acid 35%); (c) magnified view of the region C in (a) showing base material grain realignment to the material flow direction in the forged plasticized rivet metal; (d) detailed micrograph of marked are D in (a). The transition zones (interface lines) for MTMAZ, PTMAZ, and PHAZ are indicated by dashed lines
Figure 8.16 Macrographs of a CF-PEEK/TI gr. 3 metallic-insert joint, indicating the areas of interest (a, b, c, and d in the metallic part of the joint and e, f, and g in the composite part) where detailed microstructure data was acquired. (TD, ED, and FD are transverse, extrusion, and forging directions, respectively)
Figure 8.15 Schematic representation of the microstructural zones in friction-riveted metallic-insert joints. Composite base material (CBM), composite heat-affected zone (CHAZ), composite thermomechanically affected zone (CTMAZ), composite stir zone (CSZ), metal thermomechanically affected zone 1 (MHAZ 1), metal thermomechanically affected zone 2 (MTMAZ 2), and metal friction zone (MFZ) (Source: Altmeyer et al. 2015 [30]. Reproduced with permission of Elsevier).
Figure 8.17 EBSD maps showing microstructure of regions a (a) and b (b), and {0001} and {1010} pole Figure extracted from region a (c) and b (d)
Figure 8.18 EBSD maps showing microstructure of regions c (a) and d (b)
Figure 8.19 Micrograph with higher magnification of (a) area e and (b) area f (see Figure 8.16 for exact position).
Figure 8.20 Composite stir zone (CSZ): (a) enlarged image of Region 1 identified in 8.19; (b) schematic of the fiber orientation in this region; composite thermomechanically affected zone (CTMAZ): (c) enlarged image of Region 2 in 8.19 and (d) schematic of the fiber orientation in this region; (e) enlarged image of region 3; (f) enlarged image of region 4
Figure 8.21 (a) Example of a cross-sectional view of a friction-riveted PEI-GF/Ti gr.2 joint; (b) and (c) details of the volumetric thermal flaws around the rivet
Figure 8.22 (a) Infrared temperature measured during FricRiveting for the investigated joints. (b) Plot with the peak temperatures extracted from (a), versus rotational speed
Figure 8.23 (a) Size-exclusion chromatography (SEC) molecular weight distributions for investigated rotation speed specimens. (b) Influence of rotation speed on SEC polydispersivity of studied specimens
Figure 8.24 Schematic representation of microhardness distribution of a PEI/Al 2024 FricRiveting joint
Figure 8.25 Typical hardness map superimposed over the macrograph of the transversal section of joints Ti-6Al-4V/P-FV rivets joined in conditions with RS 9000 rpm (a) and RS 10,000 rpm (b) (the microstructural zones described in [28] are: Region 1 – MHAZ, Region 2 – MTMAZ₁, Region 3 – MTMAZ₂)
Figure 8.26 (a) Cross-sectional views of the selected PEI-GF/Ti gr. 2 joints (Specimens A1, A2, and A3); (b) geometrical simplifications of the anchoring zone (B1) and a simplified 3D model (B2) depicting the polymeric volume of interaction
Figure 8.27 Current description of failure modes under tensile loading in FricRiveting.
Figure 8.28 Type I fracture observed in joining condition 8. (a) Specimen after T-Pull testing. (b) Cross-sectional view of the fractured specimen (please refer to [8] for detailed descriptions of joining conditions and failure modes).
Figure 8.29 (a) Rivet pulled-out failure mode and (b) through the metallic rivet failure mode [9] (please refer to [9] for detailed descriptions of joining conditions and failure modes).
Figure 8.30 Average results of five tested specimens for tensile and lap shear testing of direct-friction-riveted joints on Al 2024-T351/PEI (joined at 21,000 rpm, 3 s, 0.8 MPa). The average curves for the pristine PEI extruded plaques and for the M5-rivets are provided for comparison
Figure 8.31 (a) Fractured tensile specimens for the pristine PEI plaques. (b) Fracture surface of the specimens in (a). Multiple crazing patterns of the fractured specimen in (a) indicating brittle fracture mechanisms. (c) Overview showing a fractured lap shear specimen on PEI/Al 2024. (d) Detailed view of the lower plaque in (c). (e) Plastic deformation (bearing) locally occurring in the polymeric volume around the rivet (not shown in the photo). Joint produced with RS: 21,000 rpm, JT:3 s, and JP:0.8 MPa
Figure 8.32 (a) X-ray tomography scan of lock-bolted Ti-6Al-4V reference joint, (b) CF-PEEK friction-riveted joints surface view, (c) compared joint efficiencies and failure mode of lock bolts and friction-riveted joints
Figure 8.33 Experimental and modeled lap shear testing results. (a) Force–displacement diagrams and (b) finite element analyses showing stress distribution of a modeled lap shear joint.
Figure 8.34 (a) Detailed view of the friction-riveted assembly and rivet shear failure; (b) bolted lap shear configuration and rivet shear failure; (c) average ultimate lap shear force results of DoE experiments and bolted joints
Figure 8.35 (a) S–N curve for selected friction riveting of Ti gr. 2/GF-PEI and AA 2198 overlap joint; (b) fatigue strength after 10⁵ cycles.
Figure 8.36 Possible FricRiveting joint geometries and applications
Figure 8.37 Friction-riveted skin–stringer component (aluminum omega-stringer and woven GF-PEI composite skin).

Chapter 9: Staking of Polymer–Metal Hybrid Structures

Figure 9.1 Basic configurations of joining parts for staking processes.
Figure 9.2 Applications of staking processes: (a) Renault Trafic front bumper assembly (Reproduced with permission of PHASA [12]); (b) car interior door assembly (Reproduced with permission of PHASA [13]), both performed by PHASA Limited (www.phasa.co.uk); (c) light truck front-end assembly (Source: Leaversuch 2003 [14] Reproduced with permission of Plastics Technology Magazine); and (d) potential application for fiber-reinforced brackets in aircraft structures.
Figure 9.3 Summary of types of staking processes.
Figure 9.4 Principle of injection clinching joining: (a) cross section of a joint using cavities in the metallic partner and (b) μCT imaging of both parts showing cavity filling of the polymer.
Figure 9.5 FricStaking: (a) tool system and preassembled parts and (b) joining sequence.
Figure 9.6 Joint formation steps in a hot staking process.
Figure 9.7 (a) Microstructural zones in a staked joint; (b) example of boundaries from the TMAZ, HAZ, and BM (or PDZ) in an F-ICJ joint of carbon-fiber-reinforced PEI; and (c) example of the PDZ in an E-ICJ joint of glass-fiber-reinforced PA66. The black arrows show microcracks.
Figure 9.8 (a) Formation of polymer–polymer interfaces; (b) visible residual weld line; and (c) healed interface.
Figure 9.9 Local mechanical properties of staked joints: (a) example of indentation profiles on a hollow PEI stake, stereomicroscopy image; (b) microhardness of profiles L1–L3 from (a), compared to PEI-BM properties; (c) contour plot of the five profiles from (a) overlaid on a light-optical microscopy image. The dotted lines in (a) and (c) show the boundary between TMAZ and BM.
Figure 9.10 (a) No-radius design; (b) surface-radius design; and (c) recessed-radius design.
Figure 9.11 Stake head geometries.
Figure 9.12 Staked joint configurations and mechanical behavior: (a) small head and no cavity filling; (b) large stake head and partial cavity filling; and (c) small stake head and complete cavity filling.
Figure 9.13 (a) Forces acting in lap-shear loading and stress concentrations analyzed through FEM and (b) forces acting in cross-tensile loading and stress concentrations analyzed through FEM. The dark gray and light gray circles indicate preferential crack nucleation points in each case.

Chapter 10: Injection Overmolding of Polymer–Metal Hybrid Structures

Figure 10.1 An example of the: (a) all-metal and (b) polymer–metal hybrid (PMH) load-bearing automotive component.
Figure 10.2 The basic concept utilized in the PMH technologies. Buckling in an open-channel all-metal component in (a) has been prevented by a rib-like plastic substructure in (b), which provides the needed lateral support.
Figure 10.3 Exploded and integrated views of a prototypical injection overmolded (simplified) load-bearing automotive body-in-white (BIW) PMH component.
Figure 10.4 Results of strength-based: (a) topology; and (b) detailed-design optimization procedures for a simplified automotive BIW structural PMH component.
Figure 10.5 An example of the mold-filling analysis results showing spatial distribution of the local filling time for the case of a vehicle PMH front-end module. (Please note that metallic stampings are not visible since they are placed within the mold cavity.)
Figure 10.6 Structural analysis of the PMH component: (a) all-metal control; (b) PMH component; (c) axial compression; (d) bending about first transverse direction; (e) bending about second transverse direction; and (f) twisting about the longitudinal direction.
Figure 10.7 Typical results pertaining to: (a) mass-normalized force versus displacement; and (b) mass-normalized torque versus torsion angle for the all-steel (control sample) and PMH component (experimental sample) used for validation of the PMH-component functionality/utility.
Figure 10.8 Key life-cycle stages for a typical PMH automotive BIW component.

Chapter 11: Ultrasonic Joining of Lightweight Alloy/Fiber-Reinforced Polymer Hybrid Structures

Figure 11.1 MIMStruct manufacturing route.
Figure 11.2 Schematic representation of the U-Joining process. (1) Positioning of joining parts; (2) Application of ultrasonic vibration and axial force; (3) Softening of the polymer by frictional heat at the interface and onset of pin insertion; (4) Polymer consolidation; and (5) End of the process and sonotrode retraction.
Figure 11.3 Possible reinforcement elements' shapes.
Figure 11.4 U-Joining process phases. P1 – Accomplishment of contact between MIMStruct pins and the surface of the composite; P2 – Coulomb friction and unsteady-state viscous dissipation; P3 – Steady-state viscous dissipation; P4 – Complete pins insertion and creation of adhesion forces at the joint interface; and P5 – Joint consolidation.
Figure 11.5 U-Joining process variations. Parallel and perpendicular vibrations of the sonotrode in relation to the joining area.
Figure 11.6 Examples of potential application for the U-Joining technique in automotive, aerospace, and infrastructure sectors.
Figure 11.7 As-sintered Ti-6Al-4V MIMStruct part (a), round-tip conical pins detail (b), and Ti-6Al-4V microstructure (c).
Figure 11.8 (a) GF-PEI composite part and (b) microstructure of the GF-PEI composite laminate.
Figure 11.9 Sonotrode tip (joining tool).
Figure 11.10 Temperature measurement area assessed by infrared thermography (a) and temperature profile (b) at the interface between the MIM-structured and GF-PEI parts for the four- and six-pin joints.
Figure 11.11 Cross-sectional view of the typical hybrid joint.
Figure 11.12 X-ray tomography and detailed micrographs of a six-pin ultrasonically joined Ti-6Al-4V/GF-PEI hybrid joint. (a) Ti-6Al-4V microstructure at MIMStruct half thickness, (b) at pin region, (c) at the surface contact between MIMStruct and sonotrode tip, (d) detail at an undercut region, (e) pin/composite interface, (f) pins tip/composite interface, (g) laser microscopy image of pin/composite interface and (h) MIMStruct bottom surface/composite interface. Microstructure of Ti-6Al-4V was revealed by Kroll etching reagent (96 mL H₂O, 6 mL HNO₃ and 2 mL HF).
Figure 11.13 Vickers microhardness maps of the MIMStrcut base material (a), four- (b) and six-pin (c) MIMStruct parts after joining. Indentations spacing were set to 0.3 mm in x and y directions and, 0.2 kgf load was applied for 10 s for each indentation.
Figure 11.14 Geometry of the lap shear specimens: (a) four- and (b) six-pin joints and their respective non-reinforced reference.
Figure 11.15 Lap shear force versus displacement curves for the non-reinforced reference, four- and six-pin hybrid joints. Curves display the replicates with the highest ULSF.
Figure 11.16 Load-bearing behavior of a six-pin joint (replicate R1), where (a) corresponds to elastic regime, (b) to adhesion failure, (c₁) to breakage of the first row of pins, and (c₂–c₆) to sequential failure of the remaining pins.
Figure 11.17 Fractographic analyses of the joint after lap shear testing. Composite fracture surface (a), fracture surface of MIMStruct part (b), and a schematic view of the shear failure location in the bottom of pins (c).
Figure 11.18 SEM analysis of the composite fracture surface. (a) Overview of a pin fracture area, (b) adhesion failure region and, (c) detail of the pin adjacent area.
Figure 11.19 SEM analysis of the MIMStruct fracture surface. (a) Overview of a pin fracture area, (b) dimples formation on the pin fracture surface and, (c) cohesive fracture region with fibers attached to the Ti-Al6-4V part.

Chapter 12: Factorial Design of Experiments for Polymer–Metal Joining

Figure 12.1 Main effects plots showing the relationship between the friction-riveting conditions ((a) RS, (b) FT, (c) FP, and (d) FoP) and the pull-out force.
Figure 12.2 Pareto charts of the standardized effects for (a) mushrooming efficiency, (b) indentation depth, (c) mechanical energy, and (d) pull-out force.
Figure 12.3 Predicted versus measured responses: (a) predicted mushrooming efficiency versus measured mushrooming efficiency; (b) predicted rivet penetration depth versus the measured rivet penetration depth; (c) predicted mech. energy input versus measured mech. energy input; and (d) predicted pull-out force versus measured pull-out force.
Figure 12.4 Main effect plots illustrating the influence of FSpJ process parameters on the normalized PDZ area.
Figure 12.5 Normalized PDZ area–process temperature relationship. Generally, higher temperatures lead to a larger PDZ area.
Figure 12.6 Interaction plot illustrating the influence of PD × JT on the normalized PDZ area.
Figure 12.7 Main effect plots illustrating the influence of FSpJ process parameters on the ultimate lap shear force.
Figure 12.8 Pareto charts of the standardized effects for (a) normalized PDZ area and (b) ULSF.
Figure 12.9 Predicted data from regression models versus experimental results for (a) the normalized PDZ area and (b) the ULSF. Cross marks (x) illustrate the DoE joining conditions, whereas black dots refer to the results of the validation joining conditions.

Chapter 13: Taguchi Design and Response Surface Methodology for Polymer–Metal Joining

Figure 13.1 Fracture surfaces of the joints after lap shear testing: (a) Run 3; (b) Run 1. Microstructure of the joint cross section: (c) Run 3; (d) Run 1.
Figure 13.2 Main effects plots for S/N ratio for each FSpJ process parameter: (a) rotational speed, (b) plunge depth, (c) joining time, and (d) joining force.
Figure 13.3 Influence of the tool rotational speed (RS) on the ULSF and bonding area.
Figure 13.4 Influence of the joining time (JT) on the ULSF and bonding area.
Figure 13.5 Influence of the plunge depth (PD) on the ULSF and nub area.
Figure 13.6 Graphical illustration of the spatial distribution of BBD design points
Figure 13.7 Main effects plots for the mean of VR for all the process parameters: (a) rotational speed, (b) friction time, (c) friction force, and (d) forging force.
Figure 13.8 Statistical model validation plot for VR.
Figure 13.9 Friction time (FT) and friction force (FF) interaction plots with volumetric ratio, VR. (a) Response surface plot and (b) contour plot.

List of Tables

Chapter 1: Principles of Adhesive Bonding

Table 1.1 Advantages and disadvantages of adhesive bonding
Table 1.2 Typical properties of adhesives
Table 1.3 Typical adhesives' mechanical properties' values
Table 1.4 Summary of some typical tests methods used to obtain the adhesive properties

Chapter 3: Friction Spot Joining (FSpJ)

Table 3.1 Controllable FSpJ process parameters and their respective functions
Table 3.2 Comparison of the mechanical performance of the FSp and bonded joints

Chapter 4: Induction Welding of Metal/Composite Hybrid Structures

Table 4.1 Typical surface treatment methods used in induction welding of metal/composite hybrid joints
Table 4.2 Surface concentrations on the treated AlMg₃ surfaces obtained by XPS analysis

Chapter 6: Principles of Mechanical Fastening in Structural Applications

Table 6.1 Hierarchical modeling for lap joint analysis
Table 6.2 Examples of galvanic material series for reducing galvanic corrosion
Table 6.3 Aluminum alloy series and respective alloy elements
Table 6.4 Summary of fastener materials
Table 6.5 Summary of plating and coating

Chapter 7: Mechanical Fastening of Composite and Composite–Metal Structures

Table 7.1 Ply elastic properties
Table 7.2 Experimental and predicted joint strengths
Table 7.3 Ply strengths and interlaminar fracture toughness
Table 7.4 Ply translaminar fracture toughness

Chapter 8: Friction Riveting of Polymer–Metal Multimaterial Structures

Table 8.1 Studied material combinations for FricRiveting (Status from December 2017)
Table 8.2 Examples of anchoring efficiencies for selected studied material combinations for FricRiveting^a

Chapter 11: Ultrasonic Joining of Lightweight Alloy/Fiber-Reinforced Polymer Hybrid Structures

Table 11.1 Metal Injection-molding process parameters
Table 11.2 Joining parameters
Table 11.3 Compilation of the lap shear testing results

Chapter 12: Factorial Design of Experiments for Polymer–Metal Joining

Table 12.1 Full-factorial design matrix showing the two levels (−1, +1) of the investigated factors and the center point configuration (0) that corresponds to the intermediate position of all factors
Table 12.2 Summary of the test results for all 17 configurations (2^k full-factorial runs and center point with six replicates)
Table 12.3 Accuracy levels of the predictions on the mechanical energy input, penetration depth, mushrooming efficiency, and pull-out force by their regression equations
Table 12.4 FSpJ process parameters (factors) and their respective levels used in the 2³-full factorial design of experiments in this work
Table 12.5 Full-factorial DoE matrix listing the 17 given joining conditions (DoE runs)
Table 12.6 Summary of the normalized PDZ area and ULSF for all of the 17 joining conditions
Table 12.7 Four sets of joining parameters to validate the regression models

Chapter 13: Taguchi Design and Response Surface Methodology for Polymer–Metal Joining

Table 13.1 Taguchi's DoE array selector
Table 13.2 Experimental mean values and standard deviations of ULSF and S/N ratios for AA6181-T4/CF-PPS joints as a function of the FSpJ parameters
Table 13.3 Main effects of the S/N ratio for the current case study
Table 13.4 Determination of α in CCD
Table 13.5 BBD design matrix for three parameters with three levels
Table 13.6 CCD design-coded levels' table
Table 13.7 CCD design matrix for the case study

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List of Contributors

André B. Abibe

Institute of Materials Research

Materials Mechanics

Solid State Joining Processes

Helmholtz-Zentrum Geesthacht

Center for Materials and Coastal Research

Geesthacht

Germany

Sergio T. Amancio-Filho

Institute of Materials Research

Materials Mechanics

Solid State Joining Processes

Helmholtz-Zentrum Geesthacht

Centre for Materials and Coastal Research

Geesthacht

Germany

and

Current affiliation:

Institute of Materials Science

Joining and Forming

Graz University of Technology

Graz

Austria

Mariana D. Banea

Departamento de Engenharia Mecânica

Faculdade de Engenharia da Universidade do Porto

Porto

Portugal

Lucian-Attila Blaga

Institute of Materials Research

Materials Mechanics

Solid State Joining Processes

Helmholtz-Zentrum Geesthacht

Center for Materials and Coastal Research

Geesthacht

Germany

Pedro P. Camanho

Departamento de Engenharia Mecânica

Faculdade de Engenharia

Universidade do Porto

Porto

Portugal

Raul D. S. G. Campilho

Departamento de Engenharia Mecânica

Instituto Superior de Engenharia do Porto

Porto

Portugal

Giuseppe Catalanotti

Departamento de Engenharia Mecânica

Faculdade de Engenharia

Universidade do Porto

Porto

Portugal

Carlos E. Chaves

Embraer S.A.

São José dos Campos

São Paulo

Brazil

Gonçalo P. Cipriano

Institute of Materials Research

Materials Mechanics

Solid State Joining Processes

Helmholtz-Zentrum Geesthacht

Centre for Materials and Coastal Research

Geesthacht

Germany

Lucas F. M. da Silva

Departamento de Engenharia Mecânica

Faculdade de Engenharia da Universidade do Porto

Porto

Portugal

Mirja Didi

Institut für Verbundwerkstoffe GmbH

University of Kaiserslautern

Kaiserslautern

Germany

Eduardo E. Feistauer

Institute of Materials Research

Materials Mechanics

Solid State Joining Processes

Helmholtz-Zentrum Geeesthacht

Centre for Materials and Coastal Research

Geesthacht

Germany

Fernando F. Fernandez

Embraer S.A.

São José dos Campos

São Paulo

Brazil

Arnaldo R. Gonzalez

Department of Mechanical Engineering DEMEC

School of Engineering

Federal University of Rio Grande do Sul

Porto Alegre

Brazil

Seyed M. Goushegir

Institute of Materials Research

Materials Mechanics

Solid State Joining Processes

Helmholtz-Zentrum Geesthacht

Centre for Materials and Coastal Research

Geesthacht

Germany

Mica Grujicic

Department of Mechanical Engineering

Clemson University

Clemson

USA

Diego J. Inforzato

Embraer S.A.

São José dos Campos

São Paulo

Brazil

Seiji Katayama

Joining and Welding Research Institute

Osaka University

Osaka

Japan

Yousuke Kawahito

Joining and Welding Research Institute

Osaka University

Osaka

Japan

Peter Mitschang

Institut für Verbundwerkstoffe GmbH

University of Kaiserslautern

Kaiserslautern

Germany

Joining of Polymer-Metal Hybrid Structures

Principles and Applications

List of Contributors