Abstract

This work investigated the feasibility of the use of a novel infusible thermoplastic resin (Elium 150 from Arkema) for composite laminate manufacture by resin infusion methods and possible application in the shipbuilding sector. We compared the properties of Elium glass-fibre laminates with those of laminates infused with state-of-the-art thermosetting epoxy and urethane acrylate resins. The Elium laminates matched the mechanical performance (flexure and interlaminar shear strength) of the epoxy and surpassed that of the urethane acrylate counterpart. However, the mechanical performance of the Elium laminates after immersion in water at 35 oC for 28 days deteriorated compared to urethane acrylate, but was comparable in flexural properties to that of the epoxy. The combination of superior mechanical performance coupled with acceptable environmental resistance and comparable composite laminate manufacturing conditions makes the infusible thermoplastic a possible future candidate matrix over commercial thermosetting resin options.

Abstract

In this work, we conducted an extensive comparative study of the water absorption behavior and retention of mechanical properties of a group of GRP composite laminates manufactured with a range of infusible thermosetting and thermoplastics resins. All laminates were manufactured by Vacuum-Assisted Resin Transfer Moulding (VARTM; the most relevant manufacturing technique in shipbuilding) with a range of state-of-the-art thermosetting resins (Urethane acrylate Crestapol 1210, Epoxy SR1125, Bio-epoxy Supersap CLR, Phenolic Cellobond J2027X) and a novel infusible acrylic thermoplastic resin (Acrylic Elium 150). The reinforcement of choice for each laminate was a unidirectional glass fabric of 996 gsm. Sample preparation for water immersion studies was according to ASTM D5229. This study was part of a comprehensive down-selection of commercially available resins in terms of their suitability for shipbuilding applications, as part of the EU H2020 project FIBRESHIP2 .  A selection of relevant properties of the laminates with different resin systems is presented in this paper including fibre volume fraction, apparent interlaminar shear strength (dry and wet condition), flexural strength (dry and wet condition) and flexural modulus (dry and wet condition).

Abstract

The study of the damage area extension in laminates made of composite materials that have been subjected to impacts, is a fundamental aspect in the evaluation of the residual properties of this type of materials. In the case of woven E-glass fibre/polyester laminates, the study of the damaged area extension by non-destructive techniques (NDT) can be carried out by visual inspection or ultrasounds. Within the techniques of ultrasonic inspection, the C-Scan type has been established as the primary inspection method. This technique is quite useful in composite laminates since it allows to quantify the total damaged area. However, this technique does not make possible the evaluation of evolution and location of  damage along the thickness, which changes remarkably in thick laminates. For this reason, it is necessary to make use of the B-Scan technique of ultrasonic inspection, whichallows to evaluate the evolution of  damage along the thickness. The aim of this experimental work is to study the evolution of  damage in woven E-glass fibre/polyestes laminates for four different thicknesses.  After being tested, these plates have been inspected through non-destructive inspection techniques (NDT) with ultrasounds (C-Scan and B-Scan) and visual inspection in order to evaluate qualitative and quantitative aspects.

Abstract

It is estimated that the aeronautic industry in the European Union produces annually around 10 tn of uncured prepreg scraps, generated mainly from manual and automated lamination processes of composites, and that the treatment cost for these residues is between 3 and 12 € per kilogram.

This work presents a technology for the reuse of the unidirectional prepreg scrap using a machine that allows the manufacturing companies, mainly form aeronautic sector, the reuse and valorisation of the leftovers of PREPREG in the workshop, involving a reduction in the economic and environmental impact.

The developed solution consists in a machine able to perform the needed processes to reuse the prepreg scrap leftovers in an automatic and efficient way, maintaining the quality and the material properties for the manufacturing of non-critical components. The equipment integrates different technologies that include computer vision to identify the shape of the leftovers and the fibre direction, cutting technology to generate regular rectangular chips aligned with the fibre direction, and a robotic system to pick and place the chips generating an ordered pattern.

The result of the process is a material sheet aiming to control the mechanical properties by using homogeneous chips with controlled fibre orientation following a predefined pattern.

Abstract

Aircraft structural components made of composite materials are susceptible of being damaged during their service life. The high level of integration and large size of these structural components may make very difficult the replacement of damaged parts; thus, repair damaged components is a solution that can save economic and temporal costs. Adhesively-bonded repairs offer certain advantages when compared to mechanical repairs, therefore there is an increasing interest in the study of their mechanical response to static loads, and a detailed structural analysis depend on several parameters. In this work, a finite-element numerical model was developed in Abaqus/Explicit commercial code. The model was validated experimentally. The numerical model was used to analyse the mechanical response of patch repaired laminates subjected to tensile static loads. The effect of the repair patch shape (rectangular or circular) and repair patch size on the failure load and  elastic stiffness  was evaluated by carrying out a series of virtual tests using the validated numerical model.