Composite RTM Process 2®

(Published on March – April 2008 – JEC Magazine #39)

JEAN-PIERRE CAUCHOIS TECHNICAL MANAGER PÔLE PLASTURGIE DE L’EST (PPE)

The software’s purpose is to provide composite industrial players (including processors, suppliers, designers, and subcontractors) an effective and user-friendly method for resolving:

• run-of-the-mill questions about designing composite parts and tooling,
• issues around RTM (conventional, light), infusion, or compression processing of composite materials.

The software’s advantages are that it deals with all development phases for a composite structure and includes a material database that can be made as comprehensive as possible through precise characterization of the resins, cores, reinforcements and other materials (permeability measurements, mechanical properties, etc.). The base then serves for design analysis, simulation, part cost analysis, etc. The software user can use the software’s database in one of two ways: 1) take the database already filled in by PPE (in cooperation with its various suppliers) as a reference, or 2) fill in the database with his own materials, using their properties for the analysis.

High added value

Composite RTM Process 2® is a very simple tool that comes with an interactive interface and a tutorial. By updating the database every years, the user will be sure to stay abreast of cost trends in the market and, more generally, keep up with the evolution of composites. Being able to work with both the SI and the US unit systems and having a choice of languages (French or English) are distinct advantages over the other computer-aided design software programmes currently on the market.

How to use the software

The software modules enable the user to define the parameters for the desired part: choice of materials, preliminary mechanical design, part fabrication data such as fill time and injection pressure, process, and financial cost. This allows him to make rapid, well-informed conclusions. The software’s modules provide all the information the user might need:

1. Choice of the most suitable material(s) for the part; mechanical data on potential structural buckling through modelling of loadbearing points and of the forces the structure will be exposed to; and the projected loads on the structure.
2. Predictive data about the part manufacturing process; for example, if the part under consideration is to be injected or infused, it can be useful to have an idea of the maximum pressure allowed if the user chooses to inject the part at constant flow, as this will facilitate tooling design.
3. Criteria for choosing the best processing technique to create the part.
4. Cost factors (labour, equipment, tooling and consumables, and materials) for determining the part’s unit cost.

1. Choice of materials and preliminary mechanical design: the structural design module (Monolithic and sandwich structure)

To get an idea of the materials to choose, the user will start by doing a preliminary design of the structure:

For the preliminary design analysis, the user can choose a sandwich or one-piece structural model:

Example – The user decides to carry out the analysis for a sandwich structure: Determining the structural design parameters:

• Parameters for the structural geometry: structural dimensions
• Structural composition: skin and core type, fibre volume and weight fractions
• Choice of load on structure: choice of load and load-bearing points

The software calculates the deflection and stresses from the parameters defined for the structure.

2. Simulating a part: the simulation module When the structural design has been determined, the simulation module can be used to obtain manufacturing information for the part. The simulation carried out provides the data on maximum pressure values and injection times needed to design the tooling.

The user can follow a procedure to simulate the part with the aid of the wizard:

• Part definition:

The user can choose among several different geometries:

For example, the user could choose a simple rectangular shape.

• Sampling definition:
  • Define geometry parameters (as a function of the shape chosen)
  • Choose reinforcement and fibre volume fraction (matching the permeability values intrinsic to the chosen reinforcement, or entering in the user’s values)
  • Choose resin viscosity
  • Determine permeability orientation as a function of the shape chosen

• Choice of injection method:

The user can choose between two different injection methods, constant rate or constant pressure, by indicating either Rate to apply or Pressure.

• Simulation results:

Depending on the geometry and method chosen for the analysis, the user will obtain the maximum pressure and injection time for an injection with frontal, lateral, and central gate points.

The user chooses a simple rectangular shape with constant rate injection for the analysis: