Introducing Fractal Dimension for Interlaminar Shear and Tensile Strength Assessment of Mechanically Interlocked Polymer–Metal Interfaces

Abstract

The interlaminar strength of mechanically interlocked polymer–metal interfaces is strongly dependent on the surface structure of the metal component. Therefore, this contribution assesses the suitability of the fractal dimension for quantification of the surface structure, as well as interlaminar strength prediction of aluminum/polyamide 6 polymer–metal hybrids. Seven different surface structures, manufactured by mechanical blasting, combined mechanical blasting and etching, thermal spraying, and laser ablation, are investigated. The experiments are carried out on a butt-bonded hollow cylinder testing method that allows shear and tensile strength determination with one specific specimen geometry. The fractal dimension of the metal surfaces is derived from cross-sectional images. For comparison, the surface roughness slope is determined and related to the interlaminar strength. Finally, a fracture analysis is conducted. For the investigated material combination, the experimental results indicate that the fractal dimension is an appropriate measure for predicting the interlaminar strength.

Surface Characteristics and Corrosion Behavior of Carbon Steel Treated by Abrasive Blasting

“…The actual roughness and anchor pattern of the steel were quantitatively evaluated using the fractal dimension method on cross-sectional SEM images. Specifically, the fractal dimension was determined by applying a box-counting algorithm [19,20] to the fractaldimensional interface line. By continuously changing the size of the squares, the number of squares covering the interface line can be counted.…”

Pin-Shaped Surface Structures Generated by Laser Single Pulse Drilling for High-Strength Interfaces in Thermally Joined Polymer–Metal Hybrids

“…After solidification, it interlocks the metal surface microstructure, thus creating a strong bonding. The thermal energy is transferred to the metal, e.g., by a heated stamp ( Figure 1 a) [ 4 , 5 , 6 , 7 , 8 ], a laser beam ( Figure 1 b) [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], an induction coil ( Figure 1 d) [ 19 , 20 , 21 , 22 ] or a rotating pin ( Figure 1 f) [ 23 , 24 , 25 , 26 , 27 ]. Techniques for creating the heat directly in the joining zone are direct laser joining using polymers with sufficient transparency ( Figure 1 c) [ 9 , 28 ] or ultrasonic welding ( Figure 1 e) [ 8 , 29 , 30 , 31 , 32 ].…”

Joining of Macroscopic 3D Steel Transition Wire Structures to Steel Sheets: Study on the Mechanical, Microstructural, and Phase Characteristics of Brazed and Glued Joints

“…Following such classic macro form-fit technologies, many new processes for micro form-fit processes through over-molding have been researched over the last few decades [13]. Several other innovative technologies like laser micro structuring on the metal surface [12,14], the mechanical interlocking effect [15,16], electrochemical treatment of metal inserts [17], fiber laser joining [18,19], and laser transmission joining [20], etc., have also been used to attain metal-plastic joints using a variety of different categories of metals and plastics. Although many researchers focused innovatively on joining metal-plastic components using various novel methodologies and technologies, the core problem of sudden property variation in the joining zone has not been elaborately discussed so far.…”