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Identifying and Remedying Multiple Trace Contaminants in Manufacturing Environment to Prevent Bond Failure

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: The objective is to define a methodology to quantify the combined effects of multiple contaminants (ie skin oil, dust, etc), composite bagging materials, corrosion prevention sealants, and environmental effects on the adhesive strength of composite material systems. 

DESCRIPTION: The use of adhesively bonded joints as an alternative to mechanical joints provide many advantages over conventional mechanical fasteners. Advantages include lower structural weight, lower fabrication cost, and improved damage tolerance. Broad DoD application is currently limited in primary structural applications due to difficulty in defining and predicting adhesive joint strength across the adhesive layer. In adhesive bonds most durability issues are driven by environmental resistance rather than fatigue loads. Furthermore, most in-service failures are caused by environmental degradation of the interface between the bonding surface and the adhesive. A strong understanding of the factors present during adhesive bond preparation, including contamination effects, need to be quantified to enable greater use of adhesively bonded structures. The proposed effort will assess the manufacturing environment for bonded structures and identify the presence of and effects that could be caused by standard bagging materials (bladders, mold release, tacky tap, PPE, bags etc.), corrosion prevention sealants (fastener sealants and molded seals, etc.), and the simultaneous presence of multiple contaminants. The effort will explore a variety of contaminant, commodity bagging materials, and shop conditions to assess how these effect adhesive bond strength. The proposed approach must identify a manufacturing scale methodology to quickly identify contaminants present on the surface and offer a feasible mitigation strategy (ie surface wipe, sand, etc). 

PHASE I: Identify at least ten different contaminant mixtures, bagging materials, and corrosion prevention sealants to assess on adhesively bonded composite surface. Identify concepts and methods to assess the adhesive bond performance in the chosen conditions. Perform laboratory testing to identify the critical amounts contaminants/transfer from manufacturing processes that could lead to reduced bond strength The Phase 1 final report will document laboratory test results and detail methods for identifying the contaminants. As part of the phase I final report, a recommendation for phase II which includes a scaled test and demonstration of the identified methodology for identifying and remediating contaminants. 

PHASE II: With promising mixtures of contaminants and transferals from manufacturing processes identified in Phase I, demonstrate ability to detect and remediate contamination of bond surface at scaled level (advancing from MRL 4 -6 during the effort). Demonstrate methodology to repeatedly assess bond quality on multiple bonding surfaces. Testing must include both mechanical tests and surface analysis to confirm bond strength in final systems. Document final results from Phase II in a final report. 

PHASE III: Demonstrate integration of methodology into a manufacturing execution system. Additionally, a digital thread approach from the manufacturing execution system to the product lifecycle management system should be included. Demonstration of detection, remediation, and data collection should be demonstrated with an OEM or Tier One supplier on a manufacturing line at the MRL 7 level. 

REFERENCES: 

1: Adhesively Bonded Joints in Composite Materials: an overview, Banea, M D

2:  da Silva, L F M. Proceedings of the Institution of Mechanical Engineers 223.L1 1-18 (2009) .

3: Review: Adhesively-Bonded Joints in Metallic Alloys, Polymers and Composite Materials: Mechanical and Environmental Durability Performance, Baldan, A

4:  Journal of Materials Science 39.15 4729-4797 (2004).

5: Clean Surfaces: Their Preparation and Characterization for Interfacial Studies, George Goldfinger, Ed., Marcel Dekker, Inc., New York, 1970.

KEYWORDS: Adhesive Bonding, Contamination, Metallic Bonding, Surface Preparation, Manufacturing, Composites 

CONTACT(S): 

Andrea Helbach (AFRL/RXMS) 

(937) 255-0083 

andrea.helbach@us.af.mil 

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