JEC COMPOSITES MAGAZINE - Issue #56 - April 2010 - 60

KNOW-HOW

SPECIAL jec composites show 2010

g…/… Applying automation to the fabrication of composite-based aerospace parts

consuming. After careful examination of the part, material type and orientation, engineers developed a work cell to manufacture the inner laminates for a radome using glass/epoxy fabric. The concept utilizes a means for manipulating fabrics and adhesive films onto a tool (Figure 7).

Fig. 8: Typical Z stringer used in aircraft design Fig. 7: Radome manufacturing cell

Accudyne Tow Path Optimization Software
To develop automation for tow/tape parts with complex geometries, Accudyne Systems has created a software tool, Tow Path Optimization Software (AT-POS®©), that models a CATIA-designed part. The software calculates the effect of strain and steering on individual tows or tapes, providing the designer crucial information about part manufacturability prior to manual fabrication and locking configuration. It also enables the automation equipment supplier to understand what the fibres will be experiencing during automation.

Within this cell, both the tool and the material move, allowing straightforward and accurate application of fabric and film. After the material is placed, a compaction step is required and a butt joint between plies is executed to adhere to the part designer’s specification that all material joints are lapped by other material. The cell also incorporates a novel bladder system for compacting and debulking each fabric ply. AFP and ATL machines cannot effectively or efficiently manufacture this part. The part centric approach recognizes the need to harmonize machine, material, method and operator to increase the rate at which this part can be manufactured.

“T” and “Z”-shaped stringers
Some aircrafts utilize a T, Z or C-shaped stringer which is placed on the surface of the fuselage and co-cured in an autoclave. The current technology consists incutting plies on an ultrasonic table, assembling them into a flat laminate and forming them over a tool. In the case of the T-shaped stringers, a “radius filler” or “noodle” must be manufactured on a separate machine and inserted into the void created at the base of the T. All of this is done by hand (except the ultrasonic cutting) and is both time consuming and expensive. It also impacts the ability to increase rate. Figure 9 shows a work cell that combines pick and place, hot drape forming, debulking and the manufacture and insertion of a noodle. Most of the previous activities done by hand are replaced by automation. Rate is significantly increased as compared with the manual process and each part has consistent, predictable quality.
Fig. 9: T & Z stringer former machine capable of forming one stringer every 10 minutes

The top of Figure 10 shows a typical part coverage when tows follow a natural path with lap or gap. The same part in which the tows were steered or forced off the natural path to ensure full coverage is shown in the lower figure. Note that full coverage does not come without significant fibre strain. Figure 11 shows the fibre strain experienced in the part where the tows were steered from their natural path to ensure optimum desired coverage. The blue areas have minimal to no strain and the other colours indicate increasing amounts of strain. With this information, the part

jec composites magazine / No56 April 2010

JEC COMPOSITES MAGAZINE - Issue #56 - April 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #56 - April 2010