JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 32

FEATURE

“Aeronautics”

Simulation

g…/… The quest for lighter and stronger aircraft with realistic simulation

Fig. 5: A proposed Isight simulation process flow, with parallel computing of the intact, delaminated, and disbanded scenarios, which will cut computing time in half

input. The Isight solver allowed the team to quickly evaluate a large number of design possibilities and identify those meeting the required parameters. To begin the stochastic analysis in Isight, the Grupo TAM engineering team looked at the manufacturing variables and tolerances, as well as the range of damage during the component life cycle, determining that there were 58 important input variables. Statistical distributions for each variable were taken from either the baseline analysis data described above or standard industry values. The team then built a calculation flow chart by using Isight’s intuitive graphical tools and icons (see Figure 4). Isight then automatically ran this analysis string repeatedly without the need for individual manual FEA analyses, with each Monte Carlo simulation including between 100 to 800 samples. Descriptive sampling was chosen because it has better convergence with the statistical distributions and requires fewer iterations. In the end, this powerful computational process identified the most critical tolerances and variables for them. With the results of this study, the team now have a clear understanding of which variables are most critical to the manufacture of composite panels that will meet the stringent quality and safety criteria.

Optimization leads to cost reduction
While the goal of optimizing the composite panel with Abaqus FEA and Isight was to increase panel strength and ultimately performance, the analysis process also provided insight into associated manufacturing, assembly and maintenance costs. The engineering team reached a number of interesting conclusions. They found that buckling pressure was the most critical factor and that a stricter material tolerance would lead to improved performance along with lower quality control and maintenance costs. They also determined that other less critical tolerances could be relaxed, resulting in both material cost savings for the carbon fibre sheets and manufacturing cost savings where lay-up tolerances are involved. In addition, the analysis demonstrated that delamination damage had a high impact on performance, while disbonding could be tolerated, especially with a new lay-up procedure. All of these results lead to resource optimization, with a quality and maintenance plan focused on the most influential inputs. Looking to the future, the Grupo TAM structural analysis department identified a number of developments that will further improve the overall cost evaluation process. For instance, parallel computing in Isight will cut computing time in half (see Figure 5). A design-to-cost strategy will also be employed, in which costing functionality will be added to the analysis using software that is currently under development in the industry and can be incorporated into Isight. This analysis process would lead to what Grupo TAM calls robust design, robust, because it takes into consideration the entire product life cycle as well as all associated costs. Incorporating such cost considerations within stochastic analyses will undoubtedly provide tremendous value to manufacturers in any industry. More information: www.tamgrupo.com

More information
The manufacturing of aircraft is evolving into a process in which a variety of specialized manufacturers are contracted to produce structures or sub-assemblies that are then assembled into a finished aircraft by the parent company. One such specialty firm is Grupo TAM, headquartered near Madrid, Spain, which manufactures auxiliary components with state-ofthe-art CNC tools. About 40% of its business is in aeronautics, including the design and manufacture of composite structures.

jec composites magazine / No58 June - July 2010

http://www.tamgrupo.com

JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010