0 sec
Place preform
Place preform
0 sec

RTM

Resin Transfer Moulding

0 sec
235 sec
430 sec
15 sec
Place Preform
10 s
Close tool, evaluate
90 sec
In-plane resin impregnation
300 sec
Cure
15sec
Demould

CRTM

Compression Resin Transfer Moulding

Viscosity

Degree of Cure
15 sec
Place Preform
18 sec
Inject resin, close tool
7 s
Through-thickness compression / impregnation
180 sec
Cure
15sec
Demould
0 sec
235 sec
430 sec
Pause / Play Animation
Replay Animation
Place preform
Inject resin, close tool
Compression/ impregnation
Cure
Demould
About

Through-thickness compression / impregnation

CRTM Tool Design
A CRTM plate tool was designed for the evaluation of the process with fast curing resins on a lab scale. Custom sealing strategies were applied in order to facilitate the partial mould opening during resin injection.
The tool is equipped with four temperature and two pressure sensors for a detailed process monitoring.
CRTM Tool Design
CRTM tool for a demonstrator part of a C-Beam section.
CRTM tool for a hollow section.

Inject resin, close tool

CRTM on Lab Scale


Preform layup : [45/0-45#-45/0/45#0]


Process Parameters:
Closing speed = 0.5 mm/s
Pressure = 10 bar
Mould temperature = 100°C
Curing time = 2 min

Through-thickness compression / impregnation

Experimental Set-Up

An experimental set-up was designed in order to reproduce the CRTM process. A reference preform material was selected and a silicone oil was used as test fluid (shown above: time lapse video x 10). The compaction and permeability of the preform and test parameters such as fluid viscosity, applied pessure and final dimensions were set as input data. Finally, the monitored impregnation process was compared with the simulation results

(shown in page 5).

Through Thickness Impregnation
Reducing flow length with CRTM
_Resin transfer moulding (RTM)
_Compression transfer moulding (CRTM)
Compaction and Permeability
The compaction response of the fabric was measured on a universal testing machine. A stack of fabrics was compacted between to compression plates and the displacement versus compaction force was recorded. The data were fitted to a hyperbolic tangent model from the literature.
Fabric permeability was measured at several fibre volume fractions and the Kozeny-Carman model was fit to the data points.
Numerical flow modelling 1/2
A one-dimensional numerical flow model was developed to study the through-thickness resin flow during CRTM. The resin pressure, fibre volume fraction and permeability distribution through the impregnation was computed. This allowed the interaction between resin flow and preform deformation to be studied.
Numerical flow modelling 2/2
The results from the flow model were compared to experiments in order to verify the accuracy of the model. The experiments have been performed on an experimental setup to reproduce the one-dimensional resin flow through the thickness of the preform. The position of the flow front, top of the preform and top of the mould were recorded at time intervals during the experiments. They were then compared to the predictions from the modelling and a good agreement was found.

Cure

Degree of Cure and Viscosity Built-Up
The curing process begins when molecules cross-link with one another, increasing the viscosity of the resin and the degree of cure. For liquid composite moulding processes a fine balance between impregnation and curing time is needed. CRTM makes possible to impregnate and cure with fast epoxy resins due to the through-thickness impregnation. The process is part-size independent and no latency of the resins is required.
Degree of Cure and Viscosity Built-Up
Modelling of the degree of cure as a function of time and temperature

Demould

Final Properties

Left: Optical microscopy image. Right: Image analysis determining a fibre content of 56 % and void content of 1.33 %.


Cross-section microscopy and C-scan showed a porosity of less than 2 %, and a fibre volume fraction of 52-56 % was determined from cross-section microscopy and subsequent digital image processing.
The mechanical characterisation of the plates (lay-up: [45/0-45#-45/0/45#0]s ) determined the following values:

Tensile Modulus = 65±4 GPa
Flexural Modulus = 53±2 GPa

These results indicate that high quality composite parts may be produced with this process.

About

Institute of Polymer Engineering (Institut für Kunststofftechnik, IKT)
Innovation in manufacturing technologies has become a key driver for the success of advanced composites. Our institute is pursuing this mission in a holistic approach to product development with polymers and fibre reinforced composites.
Contribution towards sustainable mobility
Lightweight structures are one important element of sustainable mobility. We focus on developing solutions and bringing them to the market. Our expertise comprises of:
Education
Our Bachelor and Master level courses aim at combining a theoretical background with hands-on practical experience. This is also the main reason for the ongoing success of our continuous education programmes in Polymer Engineering.
Applied research
Polymer Engineering is an inherently inter-disciplinary field. It is therefore no coincidence that designers, engineers, polymer chemists and processing experts work hand-in-hand to bring innovations to the market to the benefit of or industry partners.
Our research collaboration activities are embedded on National and European level. With national funded programmes as well as European projects.
Network
The Institute of Polymer Engineering with its staff is just one element of a Polymer Engineering Cluster, which unifies further institutions:
Our Expertise