ESI GmbH, Germany, coordinated the project.

“Composites have become the material of choice for many advanced aircraft structural applications, but research is still required to identify more cost effective manufacturing and simulation tools to optimise their manufacturing and design,” says Dr Anthony Pickett, Scientific Director at ESI GmbH. “The PreCarBi project has made a significant contribution to a new binder composite that will have a significant impact on the composite manufacturing industry and the aircraft manufacturing industry as a whole.”

The PreCarBi European Research Consortium, formed three years ago, involved 11 partners from nine countries:

• two aircraft manufacturers – Airbus and Eurocopter;
• a Tier One supplier – FACC;
• three materials manufacturers – Toho Tenax Europe, Sigmatex and Huntsman Advanced Materials (Switzerland) GmbH;
• a digital simulation software supplier – ESI Group; and
• four universities and research institutes – Cranfield University, IPM Latvia, University of Patras and SICOMP.

The main objective was to develop a new generation of bindered composite materials and associated simulation tools, specifically dedicated to high performance applications in the aerospace industry.

Background

Today, manufacturers of advanced composites use either layers of prepreg to form a laminate, or resin infusion of dry textiles (liquid composite moulding or LCM). Generally, prepreg composites have superior stiffness, strength and fatigue resistance, however the materials are expensive, have limited shapeability, require complex time-consuming manufacturing, and have limited shelf life. LCM can overcome these drawbacks but relies on low viscosity resins for infusion and suffers from fibre misalignments due to textile patterns, both leading to lower mechanical performance. The PreCarBi project was designed to improve composite materials for LCM.

Project objectives

The aim of the PreCarBi consortium was to develop new binder composite materials that allow preform designs to be manufactured and shaped under high temperature, or local tow reinforcement to be added under high temperature. This research is considered an important contribution for advanced liquid resin infusion (LRI) technologies to compete with prepreg technologies.

Description of the work

The PreCarBi project took into account three principal materials:

• new composite materials for bindered carbon yarns, developed by Tenax, in an iterative process to achieve the required performance;
• compatible resins, developed by Huntsman;
• converted new binder yarn composites into industrial preforms (woven or non-crimp fabric) produced by Sigmatex and Airbus Operations GmbH.

Additional extensive materials characterisation and testing work was performed to assess and quantify improvements as the new materials were becoming available.

From these efforts, ESI was then able to adapt its PAM-QUIKFORM and PAM-RTM simulation solutions for thermoforming and manufacturing of plastics and composites, to the industrial simulation of draping and LRI of binder yarn composites. Consequently, in the latter half of the project, industrial partners tested the new materials by applying them to industrial problems which are traditionally manufactured using prepreg technologies.

Finally, the University of Patras worked on the development of cost analysis tools to help quantify the cost reductions over prepreg manufacturing.

Different draping and injection strategies were finally tested on three industrial demonstrator parts using the new materials and the LCM manufacturing feasibility analysed.