JEC COMPOSITES MAGAZINE - Issue #93 - December 2014 - 53

- Minimize the disadvantages of multimaterial assembly (galvanic
corrosion, differential expansion, etc.)

Innovative assembly technologies
The purpose of this section is to give an idea of the technologies being developed (by manufacturers, academics, or technical centres)
for structural assemblies designed to transmit heavy loads over
time.

Fig.2: Our offering: Consulting, engineering, simulation, dimensionning,
characterization, testing, inspection, assesment, audit, industrial or legal
expertise, training for all assembly technologies

sumption reduction requirements, stand out from the competition
and penetrate new markets, reduce product, process and industrialization costs, meet the requirements for "clean" products and
manage the end of life for equipment.
To address these new challenges, manufacturers must reduce structural weight, yet guarantee performance, integrate additional functions (technical or "ecological"), optimize and simplify structural
design and integrate disassembly into design and manufacturing
processes.
Assembly processes must adapt to industrial change: integration
and combination of new materials (metals, composites, sandwich
materials, elastomers, etc.), more widespread use of higher-performing design tools, more stringent specification requirements
(weight, fatigue strength), evolution of the assembly technologies
themselves,
Goals of Cetim's in-house PAMM multimaterial assembly project
(fig 3):
- Maximize the advantages of multimaterial assembly (forming
flexibility, functional integration, etc.)

Fig.3: PAMM Multimaterial Assembly Project

Thermal assemblies
So far, homogeneous thermal welding of thermoplastic-matrix
composites is used only for the matrix. The processes used are
borrowed directly from thermoplastic welding technologies. These
welding methods are classified by heating technique (fig 4).
There are many studies on the processes used to weld thermoplastic-matrix composite materials, and these indicate that the mature
welding technologies are ultrasonic welding, induction welding,
and resistance welding. Laser welding processes have given rise to
developments such as research on the use of diode lasers, which
have wavelengths that are more adapted to polymer materials.
For heterogeneous welding (organic thermoplastic matrix/metal
composites), the bonds are mostly of the adhesive type, with
fusion-bonded matrix and adhesion to the metal. These bonds have
limited mechanical properties and are highly dependent on the
surface condition and preparation of the metal substrate and on the
type of thermoplastic matrix.
Another method is resistance welding, which can be done using
a metal meshing, or through the application of a conductive glue.
Induction welding can also be done using a metal meshing, or
directly on the electrically conductive carbon fibres (KVE Induct
technology).
There are a number of publications on welding solutions for carbon
fibres with a metal substrate; most of these solutions involve ultrasonic welding or friction stir spot welding
(FSSW). There has been a lot of research
on thermoplastic/metal laser welding, and
also work by Knapp et al. (2010) [1] on
using diode laser welding to bond long fibre
reinforced thermoplastics. Surface texturing
is another solution to increase the assembly's
mechanical strength. Research led by Andreas
Roesner [2] demonstrated the interest of
using a Yag laser to texture stainless steel
(perforations) to allow assembly with a glass
fibre reinforced polyamide 6-6 (PA66) using
laser or induction. Manutech USD (SaintEtienne, France) is developing micro- and
nanostructured solutions using femtosecond
laser. Sandblasting can also be used for microtexturing (Cetim studies, the 2012 study by
Bergmann and Stamble [3]).
No93 December 2014 /

jec composites magazine 53
JEC COMPOSITES MAGAZINE - Issue #93 - December 2014

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #93 - December 2014
