Interfacial, mechanical, and thermal behavior of PEI/glass fiber welded joints influenced by hygrothermal conditioning

This work aims to characterize the influence of hygrothermal conditioning on the mechanical and thermal behavior as well as the fractographic aspects of the interface of poly(ether imide) and glass fiber composite joints welded by electrical resistance using 400 mesh of AISI 304 stainless steel. The composites were mechanically characterized by Lap Shear Strength (LSS) and End Notched Flexure (ENF) testing to investigate maximum shear stress and energy from mode II interlaminar fracture toughness. Fractography was performed by SEM, while the influence on glass transition temperature and working temperature were evaluated by Dynamic-Mechanical Analysis and thermogravimetry. In the conditioned samples, the mechanical properties reduced 23% in the LSS test and 28% in the ENF test, while the fractography studies revealed elements of interlaminar and intralaminar fracture in both conditions. Thermal properties did not change significantly to disqualify this composite when applied to welding.

Performance improvements of a short glass fiber-reinforced PA66 composite

A plate used in a medium voltage switch, made by a 25 wt% glass fiber-reinforced polyamide 66 composite filled with flame-retardant red phosphorus (RP) (PA66-GF25 FR (RP)), was injection molded. To satisfy the relatively high dimensional accuracy requirement, a “supporting mold” was used to compensate for the difference between the transverse and longitudinal linear shrinkage of the PA66-GF25 FR (RP). To reduce the internal residual stress caused by the “supporting mold,” hygrothermal conditioning treatments, including boiling water bath at 90–100°C and re-drying at 110°C, were used. To determine the effects of boiling water bath and re-drying on the dimensional accuracy and mechanical properties of the product, three treatment routes were applied. It was found that the route in which the boiling water bath is applied after the “supporting mold” is preferred to ensure the dimensional accuracies and the mechanical properties as a whole. Using a boiling water bath as a hygrothermal conditioning treatment can improve the mechanical properties and increase the dimensional accuracy of the product. In addition, by using the preferred route, re-drying can further improve the tensile, bending, and even impact strength.

Interlaminar Shear Strength and Failure Analysis of Aluminium-Carbon Laminates with a Glass Fiber Interlayer after Moisture Absorption

This article presents selected aspects of an interlaminar shear strength and failure analysis of hybrid fiber metal laminates (FMLs) consisting of alternating layers of a 2024-T3 aluminium alloy and carbon fiber reinforced polymer. Particular attention is paid to the properties of the hybrid FMLs with an additional interlayer of glass composite at the metal-composite interface. The influence of hygrothermal conditioning, the interlaminar shear strength (short beam shear test), and the failure mode were investigated and discussed. It was found that fiber metal laminates can be classified as a material with significantly less adsorption than in the case of conventional composites. Introducing an additional layer of glass composite at the metal-composite interface and hygrothermal conditioning influence the decrease in the interlaminar shear strength. The major forms of damage to the laminates are delaminations in the layer of the carbon composite, at the metal-composite interface, and delaminations between the layers of glass and carbon composites.

Influence of mosaic pattern on hygrothermally-aged filament wound composite cylinders under axial compression

The mechanical response of composite structures may be affected by harsh environments, particularly when the matrix has a major contribution, e.g. with off-axis plies. This study aims at investigating the influence of the winding pattern on the axial compressive behavior of filament wound composite cylinder under hygrothermal conditioning. Carbon fiber-reinforced epoxy cylinders were manufactured via filament winding with 1/1, 3/1, and 5/1 mosaic winding patterns and submitted to distilled and artificial seawater environmental conditioning. Water uptake for each hygrothermal conditioning was periodically monitored. The winding pattern influenced both compressive strength and stiffness, and the environmental conditioning decreased strength up to ≈10%. The winding pattern with three diamonds around the circumference of the cylinders provides the properties in term of compressive strength and stiffness.

Effect of Mechanical Properties on Jute Fiber Reinforced By E-Glass Fiber When Treated to Change in Environment.

Fiber reinforced polymer (FRP) composites are used in various atmospheric conditions, tests are under gone for their various stress concentrations when subjected to different atmospheric conditions related to their thermal expansions .The present work aims to study the change in effects when they were subjected to hygrothermal conditioning cycles like change in temperature keeping humidity as constant and change in humidity keeping temperature as constant on Jute/ E-glass composites. Observations on tensile tests, hardness and absorption/desorption were noticed to be dependent on the nature of hygrothermal effects and SEM analysis was conducted on the specimens.