The spread of integrated structural elements and parts made from low‐density materials (for example aluminum and polymers) created a need for joining technologies with which these can be joined. Herein, the most important surface preparation methods and joining processes, with which the surface structure of aluminum can be modified and aluminum and polymer structures can be joined, are reviewed. For both topics, a new classification method is introduced: surface preparation methods are grouped based on the method of creating surface structures, whereas joining technologies are grouped according to heat input and structural changes in the polymer material. Herein, “hot” joining technologies (in which so much heat is formed that the polymer material is melted) are reviewed. This grouping category includes techniques based on friction and induction, ultrasonic and laser welding, and some in situ joining technologies. With these, materials with highly different chemical structures and melting temperatures are joined in fast cycles, in a reliable manner. In the coming years, more integrated structures containing aluminum–polymer joints manufactured with fast, automatable joining techniques (such as ultrasonic and laser welding, in compliance with the requirements of Industry 4.0) will be used throughout the industry.

In this study, the mechanical properties of ultrasonic welded lap joints of all‐polypropylene composite (APPC) were investigated and compared to the interlaminar properties of the composite sheet itself. The process control parameter was welding time: welded samples were prepared with an ultrasonic welding machine in the 0.1–1.0 second time range. In most cases, the shear strength of the welded samples exceeded that of the unwelded APPC. Although it was found that during the ultrasonic welding process, the reinforcing tapes partially melted in the welding zone (WZ), the seam remained strong enough because the heat released and the pressure applied during the welding process further improved the consolidation of the APPC layers. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48799.

The adherability and weldability of pure poly(lactic acid) (PLA) and basalt fibre-reinforced PLA were investigated in this research. The joining efficiency rate is introduced as a comparative parameter among different joining processes. In the case of adhesive bonding, 16 different adhesives were used to join specimens together. The highest bond strength and joining efficiency rate for both the pure (16 MPa, 78%) and basalt fiber-reinforced (18 MPa, 44%) adhesive-bonded specimens was achieved with acrylate-based two-component adhesives. The bond strength and joining efficiency rates of bonded specimens manufactured with four welding technologies (hot gas welding, friction stir welding, ultrasonic welding, laser welding) were also investigated. The highest bond strength for both pure PLA and basalt fibre-reinforced PLA specimens (51 MPa and 125 MPa, respectively) was attained by laser welding. The highest joining efficiency rate for pure PLA specimens (85%) was attained by ultrasonic welding, while it was achieved by laser welding for basalt-fibre reinforced PLA specimens (70%).

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In this article, our main aim is to demonstrate and prove that it is feasible to join aluminium and poly(lactic acid) (PLA) specimens by laser beam. We investigated the effects of structuring the surface of the aluminium specimens with corundum blasting and joining speed and used three types of PLA (with the same D-lactide content but different average molecular weights) to investigate the effect of the viscosity of the polymer melt on the load-bearing capacity of the joints. Joined aluminium-PLA specimens were successfully manufactured and examined with standard lap-shear tests. We found that both surface structuring, joining speed and the type of PLA material influenced the load-bearing capacity of the aluminium-PLA joint.

Purpose: To evaluate and compare the mechanical resistance to tearing of the anterior lens capsule opening after staining with different concentrations of trypan blue in ex vivo porcine eyes. Setting: Semmelweis University, and Budapest University of Technology and Economics, Budapest, Hungary. Design: Experimental study. Methods: The study comprised 75 porcine eyes. The capsule was unstained in the Control Group (n = 25 eyes), 0.06% trypan blue was used to stain the capsule in Stained 1 Group (n = 25 eyes), and 0.1% trypan blue was used to stain the capsule in Stained 2 Group (n = 25 eyes). After capsulorhexis, the capsule openings were stretched with custom-designed testing equipment until they ruptured. The rupture force (RF), circumference stretching ratio (CSR), and secant modulus at 10 mN (SM10mN) and 50 mN (SM50mN) were evaluated. Results: In total, 75 eyes were enrolled. There were no statistically significant differences in the RF (P = .8924) or CSR (P = .3876) among the groups. There were no statistically significant differences in the SM10mN (P = .8215) or SM50mN (P = .4184) among the groups. Conclusions: In this porcine eye model, the trypan blue concentrations that are routinely used in cataract surgery had no effect on capsular rim stability.

This study aimed to evaluate the changes in the endurance properties of four types of tendons caused by freezing and gamma irradiation. Four types of grafts were harvested: quadriceps, semitendinosus + gracilis, tibialis anterior, and peroneus longus. These were put into three groups: Group A was the control group, tested without freezing or irradiation. Grafts in Group B were frozen and irradiated (target dose: 21 kGy), while grafts in Group C were again frozen and irradiated (target dose: 42 kGy). Maximum load, tensile modulus, tensile strength, strain at maximum force and fracture strain were calculated from the force-elongation graphs of cyclic load tests. The higher gamma irradiation dose (Group C) significantly decreased the strains at tensile strength of the quadriceps tendons (p = 0.0004–0.0237), compared to the other two groups. In the case of the quadricep tendons (p = 0.0151), there is a significant decrease in Young’s modulus after gamma irradiation with the dose of 42 kGy. According to the results of the study, the tibialis anterior and the peroneus longus are recommended in ACL reconstruction when gamma irradiation is required, while quadricep tendons, which are usually used for an autograph, are not suitable for allograft reconstruction after gamma irradiation from the viewpoint of mechanical properties.

The aim of this paper is to determine the effect of aluminium surface preparation on the load-bearing capacity of laser-joined aluminium–polypropylene (Al-PP) specimens. The surface of the aluminium is prepared by chemical cleaning and laser engraving. The effect of pulse frequency, engraving speed and repetition number during laser engraving is investigated on the geometric parameters of the structure (straight groove) created on the surface of AA6082 aluminium alloy. Quasi-static shear testing of Al-PP joints is performed to determine how the amount and distance of the grooves affect the load-bearing capacity of the joints. The highest ultimate shear force (1250 ± 35 N) was achieved when many (21) grooves were formed with a laser engraving frequency of 20 kHz, a slow engraving speed (5 mm s−1) and many engraving repetitions (10) in the aluminium specimen. This corresponds to a shear strength of 3.1 MPa, which is 72.5% of the shear strength of the PP material used. Microscopic evaluation of joint cross-sections confirmed that the molten PP completely filled the grooves on the aluminium surface. Graphical abstract