Emerging trends in manufacturing such as light weighting, increased performance and functionality increases the use of multi-material, hybrid structures and thus the need for joining of dissimilar materials. The properties of the different materials are jointly utilised to achieve product performance. The joining processes can, on the other hand be challenging due to the same different properties. This paper reviews and summarizes state of the art research in joining dissimilar materials. Current and emerging joining technologies are reviewed according to the mechanisms of joint formation, i.e.; mechanical, chemical, thermal, or hybrid processes. Methods for process selection are described and future challenges for research on joining dissimilar materials are summarized.

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Joining of dissimilar materials

This paper investigates comprehensive knowledge regarding joining CFRP and aluminium alloys in available literature in terms of available methods, bonding processing and mechanism and properties. The methods employed comprise the use of adhesive, self-piercing rivet, bolt, clinching and welding to join only CFRP and aluminium alloys. The non-thermal joining methods received great attention though the welding process has high potential in joining these materials. Except adhesive bonding and welding, other joining methods require the penetration of metallic pins through joining parts and therefore, surface preparation is unimportant. No model is found to predict the properties of jointed structures, which makes it difficult to select one over another in applications. The choice of bonding methods depends primarily on the specific applications. The load-bearing mechanism of bolted joints is predominantly the friction that is the first stage resistance. Hybrid joints performance is enhanced by combining rivets, clinch or bolts with adhesives.

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Joining of carbon fibre reinforced polymer (CFRP) composites and aluminium alloys-A review

Joining by forming—A review on joint mechanisms, applications and future trends

Driven by increasing costs for energy and raw material and especially by the European CO2-emission laws, automotive industry faces the challenge to develop more lightweight and at the same time still rigid and crash-stable car bodies, that are affordable for large-scale production. The implementation of weight-reduced constructions depends not only on the availability of lightweight materials and related forming technologies, but also on cost-efficient and reliable joining technologies suitable for multi-material design. This article discusses the challenges and requirements for these technologies, based on the example of joining aluminium with press-hardened boron steels, what is considered as a very important material combination for affordable future lightweight mobility. Besides a presentation of recent developments for extending the process limits of conventional mechanical joining methods, new promising technologies such as resistance element welding are introduced. In addition, the performance, advantages, and disadvantages of the presented technologies are compared and discussed.

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Innovative and Highly Productive Joining Technologies for Multi-Material Lightweight Car Body Structures

Self-piercing riveting (SPR) is a cold mechanical joining process used to join two or more sheets of materials by driving a rivet piercing through the top sheet or the top and middle sheets and subsequently lock into the bottom sheet under the guidance of a suitable die. SPR is currently the main joining method for aluminium and mixed-material lightweight automotive structures. SPR was originated half century ago, but it only had significant progress in the last 25 years due to the requirement of joining lightweight materials, such as aluminium alloy structures, aluminium-steel structures and other mixed-material structures, from the automotive industry. Compared with other conventional joining methods, SPR has many advantages including no pre-drilled holes required, no fume, no spark and low noise, no surface treatment required, ability to join multi-layer materials and mixed materials and ability to produce joints with high static and fatigue strengths. In this paper, research investigations that have been conducted on self-piercing riveting will be extensively reviewed. The current state and development of SPR process is reviewed and the influence of the key process parameters on joint quality is discussed. The mechanical properties of SPR joints, the corrosion behaviour of SPR joints, the distortion of SPR joints and the simulation of SPR process and joint performance are reviewed. Developing reliable simulation methods for SPR process and joint performance to reduce the need of physical testing has been identified as one of the main challenges.

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Self-piercing riveting-a review

The analysis of lock forming mechanism in the clinching joint

Joining the car-body sheets using clinching process with various thickness and mechanical property arrangements

This paper presents the strength analysis of joining by clinching for various values of parameter X of the bottom thickness. The maximum joint strength was obtained by performing lap joints, H-shaped samples and T-shaped samples strength test. For the specified value X of the bottom thickness, a test bar of clinching joints was also subjected to complex stress state until destruction. Thus, the impact of joint load direction on the maximum load capacity was determined. The effect of radial clearance between the die and the punch on the forming process, shearing and tearing was also obtained. Moreover, the paper contains an example of new sheet metal joining technology using rivets (ClinchRivet). The complex load tests results of the rivet joints were compared with those obtained for clinching.

The clinching joints strength analysis in the aspects of changes in the forming technology and load conditions

This paper analyzes the shearing strength analysis of double joints made of various joining techniques. The capabilities of S350 GD sheet metal joining using the ClinchRivet technique were presented. The joint strength researches based on the uniaxial shearing test of the overlay joints for steel sheet of 1 mm thickness, which is used in the light gauge steel profiles in the wireframe structures of residential and commercial buildings. The results achieved for joints arranged in parallel and perpendicular to the load for specified joint spacing were discussed. The assessment of joint effectiveness were performed for both homogenous double joints and for various combinations of these joints.

The experimental analysis of the double joint type change effect on the joint destruction process in uniaxial shearing test

The paper presents the pressed joint technology using forming process with or without additional fastener. The capabilities for increasing the load-carrying ability of mechanical joints by applying...

Jacek Mucha

Papers

The analysis of lock forming mechanism in the clinching joint

Joining the car-body sheets using clinching process with various thickness and mechanical property arrangements

The clinching joints strength analysis in the aspects of changes in the forming technology and load conditions

The experimental analysis of the double joint type change effect on the joint destruction process in uniaxial shearing test

The Experimental Analysis of Forming and Strength of Clinch Riveting Sheet Metal Joint Made of Different Materials