24 August 2007
24 August 2007
The University of Delaware Center for Composite Materials (CCM) is part of a team led by Northrop Grumman Ship Systems (NGSS) that has been selected to develop a predictable and repeatable resin infusion process for fabricating carbon/vinyl-ester composite structures.
The $870K project was awarded by the Center for Naval Shipbuilding Technology (CNST) through its partnership with the Office of Naval Research and Navy ManTech.
The CNST award is yet another outgrowth of the strong foundation CCM has built in this area since the Office of Naval Research established the Advanced Materials Intelligent Processing Center (AMIPC) at CCM in 1997. Under the AMIPC, CCM researchers have created a suite of hardware and software tools including mould-filling simulations, sensor technologies, active controllers, versatile resin injection systems, and mould design methodologies for liquid composite moulding processes.
“The Navy definitely understands the value of these tools,” says Suresh Advani, Co-PI of the AMIPC program, “and they’ve been taking a proactive role in getting companies who make components for them to use these tools to reduce costs and eliminate part variability.”
The VARTM process has traditionally been used to manufacture glass-fabric laminates and sandwich constructions. The new Navy program will focus on the use of carbon fibres, which yield lighter composites with improved performance but can present manufacturing challenges.
“The problem is that the high manufacturing success rate achieved with glass-reinforced composites has not translated into the same quality for carbon parts,” says Dirk Heider, CCM Assistant Director for Technology. “Successful manufacture of carbon-reinforced marine structures like the DDG-1000 deckhouse will depend on meeting quality requirements and reducing the scrap rate.”
CCM offers a virtual manufacturing environment based on developments in flow modelling that have been packaged into a computer simulation called Liquid Injection Molding Simulation (LIMS), together with an intelligent VARTM workcell to control the process once the ideal processing parameters have been identified using the models.
“The goal is to minimize dry spots and eliminate voids,” says Heider. “This becomes increasingly challenging with parts of significant thickness or geometric complexity.” Infusion modelling methodologies and flow sensor technologies can enable optimization of techniques for more complete infusion of low-permeability fabrics.
The new program, led by system integrator NGSS, will enable the tools developed by CCM to be transitioned and validated on actual large-scale components. The twelve-month initiative will employ a “design of experiments” methodology and leverage resources from Navy ManTech’s Composites Manufacturing Technology Center and the NGSS Composites Center of Excellence, as well as CCM’s industrial consortium. According to NGSS, material savings alone are estimated at $1.7M per hull; in addition, significant labour costs will be realized via avoidances for set-up, quality assurance, and rework.
The resin flow modelling technology will be implemented at the NGSS Gulfport Operations facility. Center researchers have already made significant contributions to manufacturing operations at that site. “We worked on a pilot program with Northrop Grumman to demonstrate the value of the tools on some parts that they were having difficulty manufacturing,” Advani explains. “A team from CCM went to their Gulfport facility and successfully used the tools to fabricate the components.”
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