Clinching of Thermoplastic Composites and Metals—A Comparison of Three Novel Joining Technologies

Abstract

Clinching continuous fibre reinforced thermoplastic composites and metals is challenging due to the low ductility of the composite material. Therefore, a number of novel clinching technologies has been developed specifically for these material combinations. A systematic overview of these advanced clinching methods is given in the present paper. With a focus on process design, three selected clinching methods suitable for different joining tasks are described in detail. The clinching processes including equipment and tools, observed process phenomena and the resultant material structure are compared. Process phenomena during joining are explained in general and compared using computed tomography and micrograph images for each process. In addition the load bearing behaviour and the corresponding failure mechanisms are investigated by means of single-lap shear tests. Finally, the new joining technologies are discussed regarding application relevant criteria.

Joining Processes for Fibre-Reinforced Thermoplastics: Phenomena and Characterisation

“…Caused by the spring-loaded anvil, a counter-pressure between the sheets is applied. This leads to a stabilisation of the neck area of the punch-side sheet [ 18 ]. During the following upsetting phase, the bottom thickness of the TPC decreases with increasing punch movement [ 34 ].…”

“…For this reason, a large number of different joining systems have been developed that are specially tailored to the properties of TPCs [ 3 , 4 , 5 ]. Thus, the warm formability of TPCs is advantageously exploited in many joining processes, such as the moulding of pins into TPCs [ 6 , 7 , 8 , 9 ], flow drill joining [ 10 , 11 ], thermoclinching [ 12 , 13 , 14 ], embedding of inserts [ 15 , 16 , 17 , 18 ], moulding of contour joints [ 19 ], and hotclinching [ 20 ]. All these processes are based on warm forming the joining zone.…”

“…Therefore, they have in common a local change of the material structure. For many processes, modified fibre paths [ 7 , 15 , 18 ] as well as varying fibre volume contents (FVCs) and matrix-rich zones [ 11 , 21 , 22 , 23 ] are described as a result of the joining processes. The locally varying material structural properties in joining zones influence the load bearing behaviour and must, therefore, be taken into account when predicting the deformation and damage behaviour [ 15 ].…”

“…Transversal to the fibre direction, bending and shifting can occur. The superposition of bending and shifting is often termed reorientation [ 18 , 25 , 26 ], rearrangement [ 7 ], or displacement [ 9 ]. In the following, the term reorientation is used.…”

Experimental investigation of Al5052‐H32/PETG hybrid clinched joints

“…With the persistent innovation of various automotive lightweight technologies and the continuous emergence of various new materials, body structure optimization, manufacturing process improvement, and lightweight material application have become the frequently used approaches of automotive lightweight design in recent decades. [1][2][3][4][5] In terms of body structure optimization, four relatively perfect optimization methods have been formed with in-depth research in the automotive manufacturing field, such as topology optimization, size optimization, shape optimization, and topography optimization. In addition, in terms of manufacturing process improvement, some novel connection techniques have also been proposed in recent decades, including adhesive bonding, self-piercing riveting, mechanical clinching, laser welding, friction stir clinching, etc.…”