The mission of Composite Material (CMD) is to conduct basic and applied research in advanced materials and structures for DoD and commercial applications with emphasis on performance, reliability, affordability and technology transfer.
Composite Materials possesses broad ranging materials expertise in multifunctional structural design, fabrication, characterization, process optimization and nondestructive inspection.
Development of robust composite structures must include determination of static strength/stiffness, fatigue and impact resistance, attachment robustness, manufacturability, inspectability, maintainability, repairability and other performance attributes (e.g., noise and vibration suppression, EMI shielding, galvanic coupling, FST protection etc.). As such, CMD implements a concurrent engineering approach to successfully develop and demonstrate composite components for fleet insertion.
Design and Analysis:
CMD possesses state of the art design and analysis capabilities. Structural, acoustic and hydrodynamic design and optimization is normally completed using commercial as well as internally developed finite element, boundary element, micromechanical, and three-dimensional lamination analysis programs. Tool and component design is typically conducted using a broad suite of CAE and CAM tools including ANSYS, ABAQUS, Nastran, LS-DYNA, PAM Crash, Unigraphics, IDEAS and ProE.
Material Property Characterization:
CMD possesses extensive test and evaluation facilities including a full microscopy laboratory and several test frames. Among these are a two 33 Kip electro-mechanical test frames with a temperature controlled test chamber, a 5 Kip high speed test machine with 10 Hz maximum cyclic rate, one 110 Kip (4 Post) and three 22 Kip servo hydraulic test frames, one 22 Kip servo hydraulic test frame, five 5 Kip test frames, and a drop-weight impact tester. An 8-channel acoustic emission system supports both subelement and full scale structural testing. Fiber volume fraction determination is routinely performed using acid digestion techniques.
Fabrication facilities include; a 3' diameter x 7' Baron autoclave with computer control to 250 psi maximum pressure and 825 °F maximum temperature processing limits; meter/mix equipment with 2 component/solvent flush, heated pots/delivery lines, vacuum degassing and static mixer used for RTM and VARTM processing; a McClean Anderson filament winder with Compositrak control, 4 programmable axes suitable for both prepreg tow and wet winding; a 6' X 6' X 10' curing oven (500 °F); a hydraulic mandrel extractor and a 150 ton press. In addition ARL-Penn State maintains a machine shop with 38 stations that include six 5-axis, three 4 axis and four 3 axis CNC machining stations. ARL also has access to 0°F walk-in freezers and standalone chest freezers.
A large scale vibration isolated 6' X 6' X 5' Coordinate Measurement Machine is used to verify component tolerances down to 0.0005”. Additionally ARL Penn State possesses unique fiber volume fraction mapping software that allows fiber volume distributions to be determined from tag-end or sample sections. High sensitivity part quality measurements have been made using broad band ultrasonic scanning. Ultrasonic waveform conditioning and signal analysis has provided sensitive technology that has the capability to determine both large scale (delamination or adhesive failure) and small scale (voids and porosity) defect distributions in complex structures. Additional capabilities are available to apply thermography, shearography, laser measurement and other techniques as appropriate to particular component scales and complexities.
Advanced Seal Delivery System Composite Propeller:
CMD performed design and manufacturing functions in a program that also drew on the experience of ARL’s Fluid Dynamics and Hydro-Acoustics Divisions. In a focused concurrent engineering effort a structural load assessment was completed as the manufacturing process was being developed. Material solutions that provide optimal acoustic performance were also incorporated into the evolving design. This Integrated Product Team approach, incorporating hydrodynamic design, acoustic optimization, structural analysis, manufacturing and assembly expertise is considered crucial to the successful implementation of advanced material prototypes under aggressive program schedules.
Of course the ultimate measure of program success is customer satisfaction, and in this regard preliminary assessments have all been very positive.
Composite Manufacturing Technology for Reduced Cost Sail Cusp:
The current VIRGINIA Class Sail Cusp is stiffened steel structure comprised of numerous pieces which are welded together, filled with syntactic foam, and welded to the sail and hull structure. Considerable material and labor expense is required for the steel baseline structure due to the complex double curvature geometry involved in fabricating this part and the number of parts required for fit up. In addition, because the steel sail cusp must be welded to the sail and hull, the Sail Cusp cannot be readily removed for maintenance and thus the void space is filled almost entirely with syntactic foam to inhibit corrosion adding additional weight and manufacturing cost
CMD successfully developed an Integrated Bleed Manufacturing process that offers the potential to reduce cost by enabling the fabrication of the Sail Cusp as a one piece unstiffened monocoque composite structure bolted to the sail and hull.
DDG-1000 Radome Production Improvement:
The new generation low observable design for ship based radar is large aperture, multi-functional, fixed arrays. The cost per Zumwalt ship set for these radomes is estimated at $7M to $8M. Typical low rate initial production yield of 75% for smaller and less sophisticated missile radomes predicts an acquisition cost savings opportunity of no less than $2M if yields can near 100%. To reliably support the DDG-1000 integration schedule, yields MUST near 100%.
CMD working in conjunction with Raytheon APC advanced the producibility of these high value complex radomes by providing process characterization, more robust manufacturing processes, improved in-process inspection techniques, and demonstrated rework technologies.