Bilayer AA7075-thermoplastic composite structures manufactured by hot pressing: Effect of glass fiber amount of polypropylene composite on mechanical properties

© The Author(s) 2023.This article presents a research into the development of novel Hybrid Laminates (HLs) prepared with the use of hot-pressing method. Two types of HLs are fabricated through the composite coating with different fiber amounts (40 and 50% wt.) of only one surface of 7075-O Al alloy substrate. Effects of the fiber contents of the thermoplastic composite in the hybrid structures are investigated with regards to the tensile and flexural properties. The influence of bending load applied from different surfaces on flexural responses is also evaluated. The tensile test results indicate that the increased fiber ratio slightly affects the failure load of composite layer in the HLs. On the other hand, the flexural strength decreases with the increasing fiber amount in the HLs whether the three-point bending is performed on the Al surface or the composite layer. Scanning electron microscopy (SEM) is used to study the fracture surfaces after the mechanical characterization. From the SEM observations, it has been realized that fiber/matrix debonding is the key failure mechanism during the tensile tests. The failure mode of both HLs is delamination in the PP composite at the tensile side when the bending applied from the Al layer

Directly bonded single lap joints of SiCp/AA2124 composite with glass fiber-reinforced polypropylene: Hole drilling effects on lap shear strength and out-of-plane impact response

Joining dissimilar materials to achieve lightweight design and energy efficiency has been increasingly popular. A joint formed by components of particle-reinforced metal and polymer matrix composite combines the merits of both materials. This paper is mainly focused on the research of the tensile lap shear and impact behavior of the dissimilar single-lap joints (SLJs) between SiCp/AA2124 composite and glass fiber-reinforced polypropylene (PP). The effects of out-of-plane loading applied from different surfaces of SLJs on impact responses are evaluated. Hot pressing technique is introduced to manufacture metal/polymer assembly without using any adhesive. The hole drilling effect is investigated with the idea that it may provide weight reduction and also increase the strength of the dissimilar SLJs. The results indicate that the dissimilar SLJs show more Charpy impact strength when the impact is performed on the metal-matrix composite (MMC). Mechanical properties of SLJs are adversely affected by a drilled hole in the MMC adherend

Investigation of metal-matrix composite based hybrid laminates under quasi-static penetration and Charpy impact loading

The primary objective of the research presented here is to investigate the mechanical properties of SiCp/AA6061 based, directly-bonded hybrid laminates (HLs). Hot-pressing technique is introduced to manufacture polymer/metal/polymer HLs. Two types of thermoplastic composites (TPCs) are stacked with the metal-matrix composite (MMC). Long glass fiber-reinforced polypropylene (PP) composite sheets (20 wt% and 40 wt%) are placed in the front of and rear of the MMC plates. In this way, the effect of PP composites with different fiber amounts on perforation and Charpy impact behavior is evaluated. Failure mechanisms of the HLs are also scrutinized. The experimental results show that the HLs result in improved mechanical properties. Enhancement of the maximum penetration force is more pronounced in the HLs struck from the TPC-40. The absorbed energy in the quasi-static perforation tests is found to be up to 12.24 and 23.59 times higher compared to monolithic TPC-20 and TPC-40, respectively. The images of the damaged HLs demonstrate the plugging shear out and fiber pullout at the strike and rear faces, respectively. The MMC-based HLs also lead to the increase in the impact resistance. By replacing the blow surface from TPC-20 to TPC-40, the flatwise Charpy impact strength significantly improves from 122 kJ/m(2) to 137.11 kJ/m(2). The scanning electron microscopy (SEM) investigations after the impact experiments support that the fiber fracture is the dominant mechanism for failure mode of the faces under impact. Besides, signs of ductile fracture are seen for the MMC layer

Novel AA7075/AA2124-SiC-17p laminated structures for aerospace applications: A Comparative study into the mechanical performance of PA6 and PA66 composite interlayers

Multimaterial designs consisting of metallic and polymeric material are aimed to reach high lightweight potential. This study presents novel hybrid structures with different interlayer of thermoplastic composites not previously reported in the literature for multi-laminated composites. The metal-polymer-metal hybrids comprise of polyamide 6 (PA6) or polyamide 6,6 (PA66) composite reinforced with 15% of short glass fiber as a sandwich layer. AA7075/AA2124-SiC-17p composite laminates are bonded through hot pressing connection. Mechanical properties of the structures are experimentally investigated from the point of maximum shear strength between dissimilar laminates, resistance to fracture and energy absorbing capacity. Scanning electron microscope (SEM) analysis of fracture surfaces is carried out after mechanical characterization. Short beam three-point-bending tests show that the laminate on which the load is applied is of great importance for the asymmetric hybrid structures. Shear dominant failure is only visible when the bending load is performed from the AA7075 surface. Single-edge notched bending (SENB) test results indicate that there is no significant difference between two configurations in terms of the Mode-I fracture toughness. V-notch Charpy impact tests reveal that the interlayer of PA6 composite contributes to a 13.15% more absorbed energy than that of the PA66 interlayer

An investigation into the effects of fabric reinforcements in the bonding surface on failure response and transverse impact behavior of adhesively bonded dissimilar joints

The purpose of the current study is to evaluate the failure response and transverse impact behavior of adhesively bonded dissimilar single-lap composite joints fabricated by using fiber-reinforced polymer. The adherend materials utilized for the experimental tests were AA6082-T6 and glass fiber reinforced polymer (GFRP) in the form of thin sheets. The adhesive used was a warm to hot curing epoxy system (Araldite LY 1564 SP/Aradur 3487 BD) manufactured by Huntsman. In this study, some modifications were provided to enhance the failure response of single-lap composite joints. These modifications comprise the addition of different type and number of fabric reinforcements in the bonding surface. Based upon the test results, an increase of 33.6% in the failure load at room temperature is obtained for the joint fabricated by the addition of double-layer glass fabric reinforcement in the bonding surface. However, the failure load of all types of joint modifications decreases with the increasing tensile test temperature from room temperature to 75 degrees C. Similarly, tensile tests of the same specimen also resulted in double failure displacement by comparison with the adhesively bonded joint through only epoxy without any fabric reinforcement. The effect of low velocity impact on the failure response of the joints at the impact energy level of 2.5J is also evaluated. From the tensile tests subsequent to impact treatment, it was found that the transverse impact significantly reduced the failure load of all types of joint modifications. However, the adopted modifications provided tensile failure loads over 1875 N and 1270 N for the joint fabricated by using double-layer carbon and glass fabric reinforcements, respectively. (C) 2017 Elsevier Ltd. All rights reserved